From a02891d1eadf08e16a31f6dff96ba1af570b098e Mon Sep 17 00:00:00 2001
From: catch <catch@35733.no-reply.drupal.org>
Date: Fri, 8 Nov 2019 13:55:28 +0000
Subject: [PATCH] =?UTF-8?q?Issue=20#2742585=20by=20ZeiP,=20alexpott,=20mon?=
 =?UTF-8?q?drake,=20klausi,=20tomasnagy,=20Krzysztof=20Doma=C5=84ski,=20so?=
 =?UTF-8?q?kru,=20kristiaanvandeneynde,=20dawehner,=20jeroenbegyn:=20Depre?=
 =?UTF-8?q?cate=20dangerous=20assertTrue/False()=20compatibility=20overrid?=
 =?UTF-8?q?es=20in=20PHPUnit=20Kernel,=20Functional=20and=20FunctionalJava?=
 =?UTF-8?q?script=20tests?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../src/Functional/ActionUninstallTest.php    |  2 +-
 .../src/Functional/ConfigurationTest.php      |  2 +-
 .../src/Functional/AggregatorTestBase.php     |  4 +-
 .../Migrate/d7/MigrateAggregatorFeedTest.php  |  2 +-
 .../src/Functional/IpAddressBlockingTest.php  |  4 +-
 .../tests/src/Functional/BasicAuthTest.php    |  4 +-
 .../tests/src/Functional/BlockUiTest.php      |  4 +-
 .../src/Functional/Views/DisplayBlockTest.php | 12 +++---
 .../tests/src/Kernel/BlockStorageUnitTest.php |  2 +-
 .../tests/src/Kernel/BlockViewBuilderTest.php |  6 +--
 .../Functional/BlockContentCreationTest.php   |  6 +--
 .../src/Functional/BlockContentListTest.php   |  2 +-
 .../Functional/BlockContentListViewsTest.php  |  2 +-
 .../src/Functional/BlockContentSaveTest.php   |  2 +-
 .../src/Functional/BlockContentTypeTest.php   |  4 +-
 .../tests/src/Functional/PageEditTest.php     |  2 +-
 .../Functional/BookContentModerationTest.php  |  2 +-
 .../src/Functional/CKEditorAdminTest.php      |  8 ++--
 .../tests/src/Functional/CommentCSSTest.php   | 12 +++---
 .../src/Functional/CommentFieldsTest.php      |  4 +-
 .../src/Functional/CommentInterfaceTest.php   |  6 +--
 .../src/Functional/CommentNodeChangesTest.php |  4 +-
 .../src/Functional/CommentNonNodeTest.php     |  2 +-
 .../tests/src/Functional/CommentTestBase.php  |  2 +-
 .../tests/src/Functional/CommentTitleTest.php |  2 +-
 .../tests/src/Functional/CommentTypeTest.php  |  8 ++--
 .../Update/CommentAdminViewUpdateTest.php     |  2 +-
 .../tests/src/Functional/Views/WizardTest.php |  4 +-
 .../src/Kernel/Views/CommentLinksTest.php     |  8 ++--
 .../Functional/ConfigDependencyWebTest.php    |  8 ++--
 .../src/Functional/ConfigEntityListTest.php   |  7 ++--
 .../tests/src/Functional/ConfigEntityTest.php |  9 ++--
 .../src/Functional/ConfigImportUITest.php     |  4 +-
 .../src/Functional/ConfigInstallWebTest.php   |  3 +-
 .../src/Functional/ConfigOtherModuleTest.php  | 20 ++++-----
 .../Functional/ConfigTranslationUiTest.php    |  6 +--
 .../src/Functional/ContactPersonalTest.php    |  4 +-
 .../src/Functional/ContactSitewideTest.php    | 14 +++----
 .../Functional/Update/ContactUpdateTest.php   |  2 +-
 .../src/Functional/Views/ContactLinkTest.php  |  2 +-
 .../src/Kernel/Views/ContactFieldsTest.php    |  2 +-
 .../src/Functional/ModerationFormTest.php     | 24 +++++------
 .../src/Kernel/ContentModerationStateTest.php |  6 +--
 .../ContentTranslationLinkTagTest.php         |  2 +-
 .../ContentTranslationSettingsTest.php        |  4 +-
 .../ContentTranslationSyncImageTest.php       |  2 +-
 .../ContentTranslationUITestBase.php          |  8 ++--
 .../dblog/tests/src/Functional/DbLogTest.php  | 10 ++---
 .../src/Kernel/ConnectionFailureTest.php      |  2 +-
 .../DynamicPageCacheIntegrationTest.php       | 14 +++----
 .../tests/src/Functional/EditorAdminTest.php  |  2 +-
 .../src/Functional/EditorDialogAccessTest.php |  8 ++--
 .../EntityReferenceAutoCreateTest.php         |  4 +-
 .../EntityReferenceIntegrationTest.php        |  2 +-
 .../FieldImportDeleteUninstallUiTest.php      |  2 +-
 .../tests/src/Functional/NestedFormTest.php   |  4 +-
 .../field/tests/src/Kernel/BulkDeleteTest.php |  6 +--
 .../src/Kernel/FieldAttachStorageTest.php     |  8 ++--
 .../field/tests/src/Kernel/FieldCrudTest.php  | 12 +++---
 .../src/Kernel/FieldImportCreateTest.php      | 42 ++++++++++---------
 .../src/Kernel/FieldImportDeleteTest.php      | 10 ++---
 .../Kernel/FieldImportDeleteUninstallTest.php |  2 +-
 .../tests/src/Kernel/FieldStorageCrudTest.php |  2 +-
 .../d6/MigrateFieldWidgetSettingsTest.php     |  2 +-
 .../src/Kernel/String/UuidFormatterTest.php   |  6 +--
 .../Kernel/Views/HandlerFieldFieldTest.php    |  2 +-
 .../Functional/ManageFieldsFunctionalTest.php | 18 ++++----
 .../tests/src/Kernel/EntityDisplayTest.php    | 10 ++---
 .../src/Kernel/EntityFormDisplayTest.php      | 10 ++---
 .../tests/src/Functional/DownloadTest.php     |  2 +-
 .../src/Functional/FileFieldPathTest.php      |  2 +-
 .../src/Functional/FileFieldTestBase.php      |  2 +-
 .../tests/src/Functional/FileListingTest.php  |  3 +-
 .../tests/src/Functional/FilePrivateTest.php  |  8 ++--
 .../src/Functional/SaveUploadFormTest.php     |  4 +-
 .../tests/src/Functional/SaveUploadTest.php   |  4 +-
 .../file/tests/src/Kernel/CopyTest.php        |  6 +--
 .../file/tests/src/Kernel/DeleteTest.php      | 12 +++---
 .../file/tests/src/Kernel/LoadTest.php        |  2 +-
 .../file/tests/src/Kernel/MoveTest.php        |  8 ++--
 .../file/tests/src/Kernel/SaveDataTest.php    |  8 ++--
 .../tests/src/Functional/FilterAdminTest.php  |  2 +-
 .../src/Kernel/FilterDefaultConfigTest.php    |  2 +-
 .../src/Functional/ImageAdminStylesTest.php   |  4 +-
 .../src/Functional/ImageFieldDisplayTest.php  |  4 +-
 .../QuickEditImageControllerTest.php          |  4 +-
 .../ImageAdminStylesTest.php                  |  2 +-
 .../JsonApiFunctionalMultilingualTest.php     |  2 +-
 ...uageBrowserDetectionAcceptLanguageTest.php | 12 +++---
 .../LanguageConfigurationElementTest.php      |  4 +-
 .../LanguageUILanguageNegotiationTest.php     |  4 +-
 .../LocaleConfigTranslationTest.php           | 18 ++++----
 .../Functional/LocaleImportFunctionalTest.php |  2 +-
 .../tests/src/Functional/LocaleUpdateBase.php |  2 +-
 .../Functional/LocaleUpdateInterfaceTest.php  |  2 +-
 .../tests/src/Functional/LocaleUpdateTest.php |  2 +-
 .../tests/src/Kernel/LocaleStringTest.php     |  8 ++--
 .../src/Functional/MediaUiFunctionalTest.php  |  2 +-
 .../MediaViewsWizardTest.php                  |  4 +-
 .../EmbeddedFormWidgetTest.php                | 10 ++---
 .../FunctionalJavascript/MediaLibraryTest.php |  2 +-
 .../Functional/MenuLinkContentFormTest.php    |  2 +-
 .../Kernel/Migrate/d7/MigrateMenuLinkTest.php |  2 +-
 .../tests/src/Functional/MenuUiNodeTest.php   |  2 +-
 .../tests/src/Functional/MenuUiTest.php       |  7 ++--
 .../src/Functional/MenuUninstallTest.php      |  2 +-
 .../Kernel/MigrateEntityContentBaseTest.php   |  4 +-
 .../MigrateRollbackEntityConfigTest.php       |  4 +-
 .../tests/src/Kernel/MigrateRollbackTest.php  |  4 +-
 .../src/Tests/StubTestTrait.php               |  2 +-
 .../Functional/NodeAccessBaseTableTest.php    |  6 +--
 .../src/Functional/NodeAccessPagerTest.php    |  4 +-
 .../NodeAccessRebuildNodeGrantsTest.php       |  8 ++--
 .../NodeActionsConfigurationTest.php          |  2 +-
 .../Functional/NodeBlockFunctionalTest.php    |  2 +-
 .../tests/src/Functional/NodeCreationTest.php |  2 +-
 .../tests/src/Functional/NodeEditFormTest.php |  2 +-
 .../Functional/NodeFieldMultilingualTest.php  |  6 +--
 .../tests/src/Functional/NodeSaveTest.php     |  4 +-
 .../NodeTypeInitialLanguageTest.php           |  2 +-
 .../tests/src/Functional/NodeViewTest.php     |  6 +--
 .../tests/src/Functional/PageViewTest.php     |  2 +-
 .../src/Functional/Views/BulkFormTest.php     |  2 +-
 .../src/Functional/Views/FrontPageTest.php    |  2 +-
 .../Views/NodeRevisionWizardTest.php          |  6 +--
 .../Kernel/Config/NodeImportCreateTest.php    | 10 ++---
 .../src/Kernel/Migrate/d7/MigrateNodeTest.php |  4 +-
 .../src/Kernel/NodeAccessRecordsTest.php      |  8 ++--
 .../src/Kernel/NodeBodyFieldStorageTest.php   |  4 +-
 .../tests/src/Kernel/SummaryLengthTest.php    |  2 +-
 .../OptionsSelectDynamicValuesTest.php        |  2 +-
 .../src/Functional/OptionsWidgetsTest.php     | 14 +++----
 .../tests/src/Functional/PageCacheTest.php    | 20 ++++-----
 .../tests/src/Functional/PathAliasTest.php    |  6 +--
 .../tests/src/Functional/PathLanguageTest.php |  2 +-
 .../QuickEditCustomPipelineTest.php           |  6 +--
 .../QuickEditJavascriptTestBase.php           |  2 +-
 .../src/Kernel/Field/NumberFieldRdfaTest.php  | 16 +++----
 .../Functional/ResponsiveImageAdminUITest.php |  2 +-
 .../Kernel/ResponsiveImageIntegrationTest.php |  2 +-
 .../Functional/Views/StyleSerializerTest.php  |  8 ++--
 .../tests/src/Kernel/Views/RestExportTest.php |  2 +-
 .../SearchConfigSettingsFormTest.php          |  4 +-
 .../src/Functional/SearchRankingTest.php      |  6 +--
 .../tests/src/Functional/ShortcutSetsTest.php |  2 +-
 .../src/Functional/StatisticsAdminTest.php    |  6 +--
 .../src/Functional/Batch/ProcessingTest.php   |  2 +-
 .../tests/src/Functional/Cache/ClearTest.php  |  2 +-
 .../tests/src/Functional/Common/UrlTest.php   |  2 +-
 .../Entity/EntityCacheTagsTestBase.php        |  2 +-
 .../src/Functional/Entity/EntityFormTest.php  | 12 +++---
 .../Entity/EntityTranslationFormTest.php      |  3 +-
 .../Entity/EntityViewControllerTest.php       |  4 +-
 .../tests/src/Functional/Form/ElementTest.php | 12 +++---
 .../Form/ElementsTableSelectTest.php          | 10 ++---
 .../tests/src/Functional/Form/FormTest.php    |  7 ++--
 .../Form/ModulesListFormWebTest.php           |  2 +-
 .../Functional/Form/SystemConfigFormTest.php  |  2 +-
 .../src/Functional/Mail/HtmlToTextTest.php    |  5 +--
 .../src/Functional/Menu/LocalTasksTest.php    |  4 +-
 .../src/Functional/Module/DependencyTest.php  |  2 +-
 .../Module/InstallUninstallTest.php           |  8 ++--
 .../src/Functional/Module/ModuleTestBase.php  | 10 ++---
 .../src/Functional/Module/UninstallTest.php   |  2 +-
 .../tests/src/Functional/Pager/PagerTest.php  | 16 +++----
 .../Session/SessionAuthenticationTest.php     |  2 +-
 .../Functional/Session/SessionHttpsTest.php   |  2 +-
 .../src/Functional/Session/SessionTest.php    | 10 ++---
 .../tests/src/Functional/System/AdminTest.php |  6 +--
 .../src/Functional/System/DateTimeTest.php    |  2 +-
 .../Functional/System/ErrorHandlerTest.php    |  4 +-
 .../src/Functional/Theme/TwigTransTest.php    |  2 +-
 ...dateAddRevisionTranslationAffectedTest.php |  2 +-
 .../InstallProfileSystemInstall8300Test.php   |  2 +-
 ...sAndTasksConvertedIntoBlocksUpdateTest.php |  2 +-
 .../Functional/Update/RebuildScriptTest.php   |  2 +-
 ...LocalTasksConvertedIntoBlockUpdateTest.php |  2 +-
 .../Functional/Update/UpdateScriptTest.php    |  2 +-
 .../Migrate/d7/MigrateThemeSettingsTest.php   |  4 +-
 .../tests/src/Kernel/System/CronQueueTest.php |  4 +-
 .../tests/src/Functional/LoadMultipleTest.php |  2 +-
 .../tests/src/Functional/TermTest.php         | 10 ++---
 .../tests/src/Functional/VocabularyUiTest.php |  6 +--
 .../Migrate/MigrateTaxonomyTermStubTest.php   |  4 +-
 .../src/Functional/ToolbarAdminMenuTest.php   | 14 +++----
 .../Update/UserUpdateEmailToken.php           |  4 +-
 .../src/Functional/UserAdminListingTest.php   |  2 +-
 .../tests/src/Functional/UserAdminTest.php    |  4 +-
 .../tests/src/Functional/UserCancelTest.php   | 23 +++++-----
 .../src/Functional/UserPasswordResetTest.php  |  4 +-
 .../tests/src/Functional/UserPictureTest.php  |  2 +-
 .../src/Functional/UserRegistrationTest.php   |  4 +-
 .../src/Functional/UserRoleAdminTest.php      |  2 +-
 .../CurrentUserContextTest.php                |  2 +-
 .../Migrate/d6/MigrateUserPictureFileTest.php |  2 +-
 .../src/Kernel/Migrate/d6/MigrateUserTest.php |  2 +-
 .../src/Kernel/TempStoreDatabaseTest.php      |  4 +-
 .../tests/src/Kernel/UserMailNotifyTest.php   |  2 +-
 .../Views/HandlerArgumentUserUidTest.php      |  2 +-
 .../src/Tests/AssertViewsCacheTagsTrait.php   |  8 ++--
 .../tests/src/Functional/BulkFormTest.php     |  4 +-
 .../tests/src/Functional/GlossaryTest.php     |  2 +-
 .../tests/src/Functional/Handler/AreaTest.php |  2 +-
 .../src/Functional/Handler/FieldWebTest.php   | 40 +++++++++---------
 .../src/Functional/Handler/HandlerTest.php    |  6 +--
 .../Functional/Plugin/ArgumentDefaultTest.php |  4 +-
 .../src/Functional/Plugin/CacheTagTest.php    | 14 +++----
 .../src/Functional/Plugin/CacheWebTest.php    |  4 +-
 .../src/Functional/Plugin/DisplayFeedTest.php |  4 +-
 .../Functional/Plugin/DisplayPageWebTest.php  |  2 +-
 .../src/Functional/Plugin/DisplayTest.php     |  6 +--
 .../src/Functional/Plugin/ExposedFormTest.php |  4 +-
 .../src/Functional/Plugin/StyleTableTest.php  | 24 +++++------
 .../tests/src/Functional/ViewElementTest.php  |  8 ++--
 .../Handler/GroupedExposedFilterTest.php      | 12 +++---
 .../Entity/LatestRevisionFilterTest.php       |  2 +-
 .../src/Kernel/Handler/AreaTitleTest.php      |  2 +-
 .../src/Kernel/Handler/FieldCustomTest.php    |  2 +-
 .../tests/src/Kernel/Plugin/CacheTest.php     |  2 +-
 .../Plugin/Display/ViewsMenuLinkTest.php      | 24 +++++------
 .../tests/src/Kernel/Plugin/QueryTest.php     |  6 +--
 .../src/Kernel/Plugin/RowRenderCacheTest.php  |  2 +-
 .../tests/src/Kernel/Plugin/StyleGridTest.php | 10 ++---
 .../tests/src/Kernel/QueryGroupByTest.php     |  6 +--
 .../src/Kernel/RenderCacheIntegrationTest.php |  4 +-
 .../tests/src/Kernel/ViewElementTest.php      |  4 +-
 .../tests/src/Kernel/ViewExecutableTest.php   |  4 +-
 .../tests/src/Kernel/ViewStorageTest.php      |  2 +-
 .../tests/src/Functional/AnalyzeTest.php      |  6 +--
 .../src/Functional/CustomBooleanTest.php      | 20 ++++-----
 .../tests/src/Functional/DisplayCRUDTest.php  |  4 +-
 .../tests/src/Functional/DisplayTest.php      | 16 +++----
 .../tests/src/Functional/PreviewTest.php      |  2 +-
 .../tests/src/Functional/UITestBase.php       |  2 +-
 .../src/FunctionalJavascript/PreviewTest.php  | 30 ++++++-------
 .../Functional/WorkspaceCacheContextTest.php  |  4 +-
 .../Core/Form/FormGroupingElementsTest.php    |  4 +-
 .../FunctionalTests/BrowserTestBaseTest.php   |  2 +-
 .../BrowserTestBaseUserAgentTest.php          |  2 +-
 .../Core/Asset/AttachedAssetsTest.php         |  2 +-
 .../Asset/LibraryDiscoveryIntegrationTest.php |  4 +-
 .../Core/Cache/DatabaseBackendTagTest.php     |  2 +-
 .../Cache/GenericCacheBackendUnitTestBase.php | 18 ++++----
 .../KernelTests/Core/Command/DbDumpTest.php   | 10 ++---
 .../Core/Config/ConfigDependencyTest.php      | 30 ++++++-------
 .../Core/Config/ConfigFileContentTest.php     |  6 +--
 .../Core/Config/ConfigImporterTest.php        | 12 +++---
 .../Core/Config/ConfigInstallTest.php         |  2 +-
 .../KernelTests/Core/Database/QueryTest.php   |  4 +-
 .../Core/Entity/ContentEntityChangedTest.php  |  8 ++--
 .../Core/Entity/EntityFieldTest.php           |  9 ++--
 .../Core/Entity/EntityQueryTest.php           |  2 +-
 .../Core/Entity/EntityTranslationTest.php     |  8 ++--
 .../Core/Entity/EntityUUIDTest.php            |  2 +-
 .../Core/Entity/EntityViewBuilderTest.php     |  8 ++--
 .../ValidReferenceConstraintValidatorTest.php |  6 +--
 .../KernelTests/Core/File/FileCopyTest.php    | 10 ++---
 .../KernelTests/Core/File/FileMoveTest.php    |  8 ++--
 .../Core/File/FileSaveDataTest.php            |  2 +-
 .../Core/File/ReadOnlyStreamWrapperTest.php   |  8 ++--
 .../Core/File/StreamWrapperTest.php           | 12 +++---
 .../KernelTests/Core/Form/FormCacheTest.php   | 12 +++---
 .../DatabaseStorageExpirableTest.php          | 18 ++++----
 .../KeyValueContentEntityStorageTest.php      |  8 ++--
 .../Core/KeyValueStore/StorageTestBase.php    | 22 +++++-----
 .../Core/Menu/MenuTreeStorageTest.php         |  2 +-
 .../Render/Element/RenderElementTypesTest.php |  6 +--
 .../Core/Routing/RouteProviderTest.php        |  4 +-
 .../Core/TempStore/TempStoreDatabaseTest.php  |  4 +-
 .../KernelTests/Core/Theme/RegistryTest.php   | 10 ++---
 .../Core/Theme/ThemeInstallerTest.php         | 26 ++++++------
 .../PhpUnit6/TestCompatibilityTrait.php       |  2 +
 .../PhpUnit7/TestCompatibilityTrait.php       |  2 +
 .../Assert/KernelAssertLegacyTraitTest.php    | 31 ++++++++++++++
 274 files changed, 851 insertions(+), 820 deletions(-)
 create mode 100644 core/tests/Drupal/Tests/Core/Assert/KernelAssertLegacyTraitTest.php

diff --git a/core/modules/action/tests/src/Functional/ActionUninstallTest.php b/core/modules/action/tests/src/Functional/ActionUninstallTest.php
index 5e3718044e5..58e652b791c 100644
--- a/core/modules/action/tests/src/Functional/ActionUninstallTest.php
+++ b/core/modules/action/tests/src/Functional/ActionUninstallTest.php
@@ -33,7 +33,7 @@ class ActionUninstallTest extends BrowserTestBase {
 
     $storage = $this->container->get('entity_type.manager')->getStorage('action');
     $storage->resetCache(['user_block_user_action']);
-    $this->assertTrue($storage->load('user_block_user_action'), 'Configuration entity \'user_block_user_action\' still exists after uninstalling action module.');
+    $this->assertNotEmpty($storage->load('user_block_user_action'), 'Configuration entity \'user_block_user_action\' still exists after uninstalling action module.');
 
     $admin_user = $this->drupalCreateUser(['administer users']);
     $this->drupalLogin($admin_user);
diff --git a/core/modules/action/tests/src/Functional/ConfigurationTest.php b/core/modules/action/tests/src/Functional/ConfigurationTest.php
index 06510ecc80a..05421b7b0d0 100644
--- a/core/modules/action/tests/src/Functional/ConfigurationTest.php
+++ b/core/modules/action/tests/src/Functional/ConfigurationTest.php
@@ -89,7 +89,7 @@ class ConfigurationTest extends BrowserTestBase {
     $this->assertNoText($new_action_label, "Make sure the action label does not appear on the overview page after we've deleted the action.");
 
     $action = Action::load($action_id);
-    $this->assertFalse($action, 'Make sure the action is gone after being deleted.');
+    $this->assertNull($action, 'Make sure the action is gone after being deleted.');
   }
 
 }
diff --git a/core/modules/aggregator/tests/src/Functional/AggregatorTestBase.php b/core/modules/aggregator/tests/src/Functional/AggregatorTestBase.php
index b4c80d0bd3a..baac8f69bf8 100644
--- a/core/modules/aggregator/tests/src/Functional/AggregatorTestBase.php
+++ b/core/modules/aggregator/tests/src/Functional/AggregatorTestBase.php
@@ -221,10 +221,10 @@ abstract class AggregatorTestBase extends BrowserTestBase {
     $count_query = \Drupal::entityQuery('aggregator_item')->condition('fid', $feed->id())->count();
     $this->updateFeedItems($feed, $expected_count);
     $count = $count_query->execute();
-    $this->assertTrue($count);
+    $this->assertGreaterThan(0, $count);
     $this->deleteFeedItems($feed);
     $count = $count_query->execute();
-    $this->assertTrue($count == 0);
+    $this->assertEquals(0, $count);
   }
 
   /**
diff --git a/core/modules/aggregator/tests/src/Kernel/Migrate/d7/MigrateAggregatorFeedTest.php b/core/modules/aggregator/tests/src/Kernel/Migrate/d7/MigrateAggregatorFeedTest.php
index fd208238c77..401ea048fe4 100644
--- a/core/modules/aggregator/tests/src/Kernel/Migrate/d7/MigrateAggregatorFeedTest.php
+++ b/core/modules/aggregator/tests/src/Kernel/Migrate/d7/MigrateAggregatorFeedTest.php
@@ -47,7 +47,7 @@ class MigrateAggregatorFeedTest extends MigrateDrupal7TestBase {
     $this->assertNull($feed->getImage());
     // As with getLastCheckedTime(), the etag can change as the fixture is
     // updated normally, so assert that its format is correct.
-    $this->assertTrue(preg_match('/^"[a-z0-9]{32}"$/', $feed->getEtag()));
+    $this->assertRegExp('/^"[a-z0-9]{32}"$/', $feed->getEtag());
     $this->assertIdentical('0', $feed->getLastModified());
   }
 
diff --git a/core/modules/ban/tests/src/Functional/IpAddressBlockingTest.php b/core/modules/ban/tests/src/Functional/IpAddressBlockingTest.php
index bb77517e40b..344678c30e9 100644
--- a/core/modules/ban/tests/src/Functional/IpAddressBlockingTest.php
+++ b/core/modules/ban/tests/src/Functional/IpAddressBlockingTest.php
@@ -40,7 +40,7 @@ class IpAddressBlockingTest extends BrowserTestBase {
     $edit['ip'] = '1.2.3.3';
     $this->drupalPostForm('admin/config/people/ban', $edit, t('Add'));
     $ip = $connection->query("SELECT iid from {ban_ip} WHERE ip = :ip", [':ip' => $edit['ip']])->fetchField();
-    $this->assertTrue($ip, 'IP address found in database.');
+    $this->assertNotEmpty($ip, 'IP address found in database.');
     $this->assertRaw(t('The IP address %ip has been banned.', ['%ip' => $edit['ip']]), 'IP address was banned.');
 
     // Try to block an IP address that's already blocked.
@@ -71,7 +71,7 @@ class IpAddressBlockingTest extends BrowserTestBase {
     $submit_ip = '1.2.3.4';
     $this->drupalPostForm('admin/config/people/ban/' . $submit_ip, [], t('Add'));
     $ip = $connection->query("SELECT iid from {ban_ip} WHERE ip = :ip", [':ip' => $submit_ip])->fetchField();
-    $this->assertTrue($ip, 'IP address found in database');
+    $this->assertNotEmpty($ip, 'IP address found in database');
     $this->assertRaw(t('The IP address %ip has been banned.', ['%ip' => $submit_ip]), 'IP address was banned.');
 
     // Submit your own IP address. This fails, although it works when testing
diff --git a/core/modules/basic_auth/tests/src/Functional/BasicAuthTest.php b/core/modules/basic_auth/tests/src/Functional/BasicAuthTest.php
index 55b7fc15ead..16446ad3322 100644
--- a/core/modules/basic_auth/tests/src/Functional/BasicAuthTest.php
+++ b/core/modules/basic_auth/tests/src/Functional/BasicAuthTest.php
@@ -46,7 +46,7 @@ class BasicAuthTest extends BrowserTestBase {
     $this->assertText($account->getAccountName(), 'Account name is displayed.');
     $this->assertResponse('200', 'HTTP response is OK');
     $this->mink->resetSessions();
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
     $this->assertIdentical(strpos($this->drupalGetHeader('Cache-Control'), 'public'), FALSE, 'Cache-Control is not set to public');
 
     $this->basicAuthGet($url, $account->getAccountName(), $this->randomMachineName());
@@ -74,7 +74,7 @@ class BasicAuthTest extends BrowserTestBase {
     $this->drupalGet($url);
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS');
     $this->basicAuthGet($url, $account->getAccountName(), $account->pass_raw);
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
     $this->assertIdentical(strpos($this->drupalGetHeader('Cache-Control'), 'public'), FALSE, 'No page cache response when requesting a cached page with basic auth credentials.');
   }
 
diff --git a/core/modules/block/tests/src/Functional/BlockUiTest.php b/core/modules/block/tests/src/Functional/BlockUiTest.php
index a3fc1bb180b..7e98e70938d 100644
--- a/core/modules/block/tests/src/Functional/BlockUiTest.php
+++ b/core/modules/block/tests/src/Functional/BlockUiTest.php
@@ -356,11 +356,11 @@ class BlockUiTest extends BrowserTestBase {
     $arguments = [':message' => 'Only digits are allowed'];
     $pattern = '//div[contains(@class,"messages messages--error")]/div[contains(text()[2],:message)]';
     $elements = $this->xpath($pattern, $arguments);
-    $this->assertTrue($elements, 'Plugin error message found in parent form.');
+    $this->assertNotEmpty($elements, 'Plugin error message found in parent form.');
 
     $error_class_pattern = '//div[contains(@class,"form-item-settings-digits")]/input[contains(@class,"error")]';
     $error_class = $this->xpath($error_class_pattern);
-    $this->assertTrue($error_class, 'Plugin error class found in parent form.');
+    $this->assertNotEmpty($error_class, 'Plugin error class found in parent form.');
   }
 
   /**
diff --git a/core/modules/block/tests/src/Functional/Views/DisplayBlockTest.php b/core/modules/block/tests/src/Functional/Views/DisplayBlockTest.php
index 77bb711b72a..211847c5d00 100644
--- a/core/modules/block/tests/src/Functional/Views/DisplayBlockTest.php
+++ b/core/modules/block/tests/src/Functional/Views/DisplayBlockTest.php
@@ -162,10 +162,10 @@ class DisplayBlockTest extends ViewTestBase {
     $view->displayHandlers->remove('block_1');
     $view->storage->save();
 
-    $this->assertFalse($block_storage->load($block_1->id()), 'The block for this display was removed.');
-    $this->assertFalse($block_storage->load($block_2->id()), 'The block for this display was removed.');
-    $this->assertTrue($block_storage->load($block_3->id()), 'A block from another view was unaffected.');
-    $this->assertTrue($block_storage->load($block_4->id()), 'A block from another view was unaffected.');
+    $this->assertNull($block_storage->load($block_1->id()), 'The block for this display was removed.');
+    $this->assertNull($block_storage->load($block_2->id()), 'The block for this display was removed.');
+    $this->assertNotEmpty($block_storage->load($block_3->id()), 'A block from another view was unaffected.');
+    $this->assertNotEmpty($block_storage->load($block_4->id()), 'A block from another view was unaffected.');
     $this->drupalGet('test-page');
     $this->assertNoBlockAppears($block_1);
     $this->assertNoBlockAppears($block_2);
@@ -179,8 +179,8 @@ class DisplayBlockTest extends ViewTestBase {
     $view->displayHandlers->remove('block_1');
     $view->storage->save();
 
-    $this->assertFalse($block_storage->load($block_3->id()), 'The block for this display was removed.');
-    $this->assertTrue($block_storage->load($block_4->id()), 'A block from another display on the same view was unaffected.');
+    $this->assertNull($block_storage->load($block_3->id()), 'The block for this display was removed.');
+    $this->assertNotEmpty($block_storage->load($block_4->id()), 'A block from another display on the same view was unaffected.');
     $this->drupalGet('test-page');
     $this->assertNoBlockAppears($block_3);
     $this->assertBlockAppears($block_4);
diff --git a/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php b/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
index 4b13f9c6dd5..09abf2ad3ae 100644
--- a/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
@@ -117,7 +117,7 @@ class BlockStorageUnitTest extends KernelTestBase {
     $this->assertSame('content', $entity->getRegion());
     $this->assertTrue($entity->status());
     $this->assertEqual($entity->getTheme(), 'stark');
-    $this->assertTrue($entity->uuid());
+    $this->assertNotEmpty($entity->uuid());
   }
 
   /**
diff --git a/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php b/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
index 95a444deded..a70e89c3183 100644
--- a/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
@@ -156,7 +156,7 @@ class BlockViewBuilderTest extends KernelTestBase {
     $build = $this->getBlockRenderArray();
     $cid = 'entity_view:block:test_block:' . implode(':', \Drupal::service('cache_contexts_manager')->convertTokensToKeys(['languages:' . LanguageInterface::TYPE_INTERFACE, 'theme', 'user.permissions'])->getKeys());
     $this->renderer->renderRoot($build);
-    $this->assertTrue($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
 
     // Re-save the block and check that the cache entry has been deleted.
     $this->block->save();
@@ -170,7 +170,7 @@ class BlockViewBuilderTest extends KernelTestBase {
     $build['#block'] = $this->block;
 
     $this->renderer->renderRoot($build);
-    $this->assertTrue($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
     $this->block->delete();
     $this->assertFalse($this->container->get('cache.render')->get($cid), 'The block render cache entry has been cleared when the block was deleted.');
 
@@ -307,7 +307,7 @@ class BlockViewBuilderTest extends KernelTestBase {
     $final_cache_contexts = Cache::mergeContexts($expected_contexts, $required_cache_contexts);
     $cid = implode(':', $expected_keys) . ':' . implode(':', \Drupal::service('cache_contexts_manager')->convertTokensToKeys($final_cache_contexts)->getKeys());
     $cache_item = $this->container->get('cache.render')->get($cid);
-    $this->assertTrue($cache_item, 'The block render element has been cached with the expected cache ID.');
+    $this->assertNotEmpty($cache_item, 'The block render element has been cached with the expected cache ID.');
     $this->assertIdentical(Cache::mergeTags($expected_tags, ['rendered']), $cache_item->tags);
     $this->assertIdentical($final_cache_contexts, $cache_item->data['#cache']['contexts']);
     $this->assertIdentical($expected_tags, $cache_item->data['#cache']['tags']);
diff --git a/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php b/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php
index 5bfd624e5ca..7f3b2513811 100644
--- a/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php
+++ b/core/modules/block_content/tests/src/Functional/BlockContentCreationTest.php
@@ -72,7 +72,7 @@ class BlockContentCreationTest extends BlockContentTestBase {
       ->getStorage('block_content')
       ->loadByProperties(['info' => $edit['info[0][value]']]);
     $block = reset($blocks);
-    $this->assertTrue($block, 'Custom Block found in database.');
+    $this->assertNotEmpty($block, 'Custom Block found in database.');
 
     // Check that attempting to create another block with the same value for
     // 'info' returns an error.
@@ -154,7 +154,7 @@ class BlockContentCreationTest extends BlockContentTestBase {
       ->getStorage('block_content')
       ->loadByProperties(['info' => $edit['info[0][value]']]);
     $block = reset($blocks);
-    $this->assertTrue($block, 'Custom Block found in database.');
+    $this->assertNotEmpty($block, 'Custom Block found in database.');
 
     // Check that attempting to create another block with the same value for
     // 'info' returns an error.
@@ -191,7 +191,7 @@ class BlockContentCreationTest extends BlockContentTestBase {
       ->getStorage('block_content')
       ->loadByProperties(['info' => $edit['info[0][value]']]);
     $block = reset($blocks);
-    $this->assertTrue($block, 'Default Custom Block found in database.');
+    $this->assertNotEmpty($block, 'Default Custom Block found in database.');
   }
 
   /**
diff --git a/core/modules/block_content/tests/src/Functional/BlockContentListTest.php b/core/modules/block_content/tests/src/Functional/BlockContentListTest.php
index ae56cda1fc1..61edfdaefd7 100644
--- a/core/modules/block_content/tests/src/Functional/BlockContentListTest.php
+++ b/core/modules/block_content/tests/src/Functional/BlockContentListTest.php
@@ -39,7 +39,7 @@ class BlockContentListTest extends BlockContentTestBase {
 
     // Test for the table.
     $element = $this->xpath('//div[@class="layout-content"]//table');
-    $this->assertTrue($element, 'Configuration entity list table found.');
+    $this->assertNotEmpty($element, 'Configuration entity list table found.');
 
     // Test the table header.
     $elements = $this->xpath('//div[@class="layout-content"]//table/thead/tr/th');
diff --git a/core/modules/block_content/tests/src/Functional/BlockContentListViewsTest.php b/core/modules/block_content/tests/src/Functional/BlockContentListViewsTest.php
index ca896c613f9..61f29847185 100644
--- a/core/modules/block_content/tests/src/Functional/BlockContentListViewsTest.php
+++ b/core/modules/block_content/tests/src/Functional/BlockContentListViewsTest.php
@@ -41,7 +41,7 @@ class BlockContentListViewsTest extends BlockContentTestBase {
 
     // Test for the table.
     $element = $this->xpath('//div[@class="layout-content"]//table');
-    $this->assertTrue($element, 'Views table found.');
+    $this->assertNotEmpty($element, 'Views table found.');
 
     // Test the table header.
     $elements = $this->xpath('//div[@class="layout-content"]//table/thead/tr/th');
diff --git a/core/modules/block_content/tests/src/Functional/BlockContentSaveTest.php b/core/modules/block_content/tests/src/Functional/BlockContentSaveTest.php
index 5b89d4d1b94..b62ea413d84 100644
--- a/core/modules/block_content/tests/src/Functional/BlockContentSaveTest.php
+++ b/core/modules/block_content/tests/src/Functional/BlockContentSaveTest.php
@@ -56,7 +56,7 @@ class BlockContentSaveTest extends BlockContentTestBase {
 
     // Test the import saved.
     $block_by_id = BlockContent::load($test_id);
-    $this->assertTrue($block_by_id, 'Custom block load by block ID.');
+    $this->assertNotEmpty($block_by_id, 'Custom block load by block ID.');
     $this->assertIdentical($block_by_id->body->value, $block_array['body']['value']);
   }
 
diff --git a/core/modules/block_content/tests/src/Functional/BlockContentTypeTest.php b/core/modules/block_content/tests/src/Functional/BlockContentTypeTest.php
index 2e172551318..9a8f6b59642 100644
--- a/core/modules/block_content/tests/src/Functional/BlockContentTypeTest.php
+++ b/core/modules/block_content/tests/src/Functional/BlockContentTypeTest.php
@@ -71,7 +71,7 @@ class BlockContentTypeTest extends BlockContentTestBase {
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
     $block_type = BlockContentType::load('foo');
-    $this->assertTrue($block_type, 'The new block type has been created.');
+    $this->assertInstanceOf(BlockContentType::class, $block_type, 'The new block type has been created.');
 
     $field_definitions = \Drupal::service('entity_field.manager')->getFieldDefinitions('block_content', 'foo');
     $this->assertTrue(isset($field_definitions['body']), 'Body field created when using the UI to create block content types.');
@@ -90,7 +90,7 @@ class BlockContentTypeTest extends BlockContentTestBase {
     $this->assertFalse(isset($field_definitions['body']), "Body field for 'other' block type not created when using the testing API to create block content types.");
 
     $block_type = BlockContentType::load('other');
-    $this->assertTrue($block_type, 'The new block type has been created.');
+    $this->assertInstanceOf(BlockContentType::class, $block_type, 'The new block type has been created.');
 
     $this->drupalGet('block/add/' . $block_type->id());
     $this->assertResponse(200);
diff --git a/core/modules/block_content/tests/src/Functional/PageEditTest.php b/core/modules/block_content/tests/src/Functional/PageEditTest.php
index 1cc8c1946ca..fc39ab44b30 100644
--- a/core/modules/block_content/tests/src/Functional/PageEditTest.php
+++ b/core/modules/block_content/tests/src/Functional/PageEditTest.php
@@ -40,7 +40,7 @@ class PageEditTest extends BlockContentTestBase {
     // Check that the block exists in the database.
     $blocks = \Drupal::entityQuery('block_content')->condition('info', $edit['info[0][value]'])->execute();
     $block = BlockContent::load(reset($blocks));
-    $this->assertTrue($block, 'Custom block found in database.');
+    $this->assertNotEmpty($block, 'Custom block found in database.');
 
     // Load the edit page.
     $this->drupalGet('block/' . $block->id());
diff --git a/core/modules/book/tests/src/Functional/BookContentModerationTest.php b/core/modules/book/tests/src/Functional/BookContentModerationTest.php
index 00c234dafa1..6a1ce9c78b2 100644
--- a/core/modules/book/tests/src/Functional/BookContentModerationTest.php
+++ b/core/modules/book/tests/src/Functional/BookContentModerationTest.php
@@ -70,7 +70,7 @@ class BookContentModerationTest extends BrowserTestBase {
     ];
     $this->drupalPostForm('node/add/book', $edit, t('Save'));
     $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
-    $this->assertTrue($node);
+    $this->assertNotEmpty($node);
 
     $edit = [
       'moderation_state[0][state]' => 'draft',
diff --git a/core/modules/ckeditor/tests/src/Functional/CKEditorAdminTest.php b/core/modules/ckeditor/tests/src/Functional/CKEditorAdminTest.php
index 87c358cd684..26b71553ece 100644
--- a/core/modules/ckeditor/tests/src/Functional/CKEditorAdminTest.php
+++ b/core/modules/ckeditor/tests/src/Functional/CKEditorAdminTest.php
@@ -61,7 +61,7 @@ class CKEditorAdminTest extends BrowserTestBase {
 
     // Ensure no Editor config entity exists yet.
     $editor = Editor::load('filtered_html');
-    $this->assertFalse($editor, 'No Editor config entity exists yet.');
+    $this->assertNull($editor, 'No Editor config entity exists yet.');
 
     // Verify the "Text Editor" <select> when a text editor is available.
     $select = $this->xpath('//select[@name="editor[editor]"]');
@@ -117,7 +117,7 @@ class CKEditorAdminTest extends BrowserTestBase {
     // Keep the "CKEditor" editor selected and click the "Configure" button.
     $this->drupalPostForm(NULL, $edit, 'editor_configure');
     $editor = Editor::load('filtered_html');
-    $this->assertFalse($editor, 'No Editor config entity exists yet.');
+    $this->assertNull($editor, 'No Editor config entity exists yet.');
 
     // Ensure that drupalSettings is correct.
     $ckeditor_settings_toolbar = [
@@ -266,9 +266,9 @@ class CKEditorAdminTest extends BrowserTestBase {
     ];
     $this->drupalPostForm(NULL, $edit, 'editor_configure');
     $filter_format = FilterFormat::load('amazing_format');
-    $this->assertFalse($filter_format, 'No FilterFormat config entity exists yet.');
+    $this->assertNull($filter_format, 'No FilterFormat config entity exists yet.');
     $editor = Editor::load('amazing_format');
-    $this->assertFalse($editor, 'No Editor config entity exists yet.');
+    $this->assertNull($editor, 'No Editor config entity exists yet.');
 
     // Ensure the toolbar buttons configuration value is initialized to the
     // default value.
diff --git a/core/modules/comment/tests/src/Functional/CommentCSSTest.php b/core/modules/comment/tests/src/Functional/CommentCSSTest.php
index 54db7a1636d..5f14adcf823 100644
--- a/core/modules/comment/tests/src/Functional/CommentCSSTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentCSSTest.php
@@ -95,19 +95,19 @@ class CommentCSSTest extends CommentTestBase {
         // Verify the by-anonymous class.
         $comments = $this->xpath('//*[contains(@class, "comment") and contains(@class, "by-anonymous")]');
         if ($case['comment_uid'] == 0) {
-          $this->assertTrue(count($comments) == 1, 'by-anonymous class found.');
+          $this->assertCount(1, $comments, 'by-anonymous class found.');
         }
         else {
-          $this->assertFalse(count($comments), 'by-anonymous class not found.');
+          $this->assertCount(0, $comments, 'by-anonymous class not found.');
         }
 
         // Verify the by-node-author class.
         $comments = $this->xpath('//*[contains(@class, "comment") and contains(@class, "by-node-author")]');
         if ($case['comment_uid'] > 0 && $case['comment_uid'] == $case['node_uid']) {
-          $this->assertTrue(count($comments) == 1, 'by-node-author class found.');
+          $this->assertCount(1, $comments, 'by-node-author class found.');
         }
         else {
-          $this->assertFalse(count($comments), 'by-node-author class not found.');
+          $this->assertCount(0, $comments, 'by-node-author class not found.');
         }
 
         // Verify the data-comment-user-id attribute, which is used by the
@@ -121,10 +121,10 @@ class CommentCSSTest extends CommentTestBase {
       // Verify the unpublished class.
       $comments = $this->xpath('//*[contains(@class, "comment") and contains(@class, "unpublished")]');
       if ($case['comment_status'] == CommentInterface::NOT_PUBLISHED && $case['user'] == 'admin') {
-        $this->assertTrue(count($comments) == 1, 'unpublished class found.');
+        $this->assertCount(1, $comments, 'unpublished class found.');
       }
       else {
-        $this->assertFalse(count($comments), 'unpublished class not found.');
+        $this->assertCount(0, $comments, 'unpublished class not found.');
       }
 
       // Verify the data-comment-timestamp attribute, which is used by the
diff --git a/core/modules/comment/tests/src/Functional/CommentFieldsTest.php b/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
index 52230391679..1dd250d5068 100644
--- a/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
@@ -45,7 +45,7 @@ class CommentFieldsTest extends CommentTestBase {
     // Check that the 'comment_body' field is not deleted since it is persisted
     // even if it has no fields.
     $field_storage = FieldStorageConfig::loadByName('comment', 'comment_body');
-    $this->assertTrue($field_storage, 'The comment_body field storage was not deleted');
+    $this->assertInstanceOf(FieldStorageConfig::class, $field_storage, 'The comment_body field storage was not deleted');
 
     // Create a new content type.
     $type_name = 'test_node_type_2';
@@ -55,7 +55,7 @@ class CommentFieldsTest extends CommentTestBase {
     // Check that the 'comment_body' field exists and has an instance on the
     // new comment bundle.
     $field_storage = FieldStorageConfig::loadByName('comment', 'comment_body');
-    $this->assertTrue($field_storage, 'The comment_body field exists');
+    $this->assertInstanceOf(FieldStorageConfig::class, $field_storage, 'The comment_body field exists');
     $field = FieldConfig::loadByName('comment', 'comment', 'comment_body');
     $this->assertTrue(isset($field), new FormattableMarkup('The comment_body field is present for comments on type @type', ['@type' => $type_name]));
 
diff --git a/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php b/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php
index 9514664b669..2d3dcaa5d14 100644
--- a/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php
@@ -178,21 +178,21 @@ class CommentInterfaceTest extends CommentTestBase {
 
     // Attempt to post to node with comments disabled.
     $this->node = $this->drupalCreateNode(['type' => 'article', 'promote' => 1, 'comment' => [['status' => CommentItemInterface::HIDDEN]]]);
-    $this->assertTrue($this->node, 'Article node created.');
+    $this->assertNotNull($this->node, 'Article node created.');
     $this->drupalGet('comment/reply/node/' . $this->node->id() . '/comment');
     $this->assertResponse(403);
     $this->assertNoField('edit-comment', 'Comment body field found.');
 
     // Attempt to post to node with read-only comments.
     $this->node = $this->drupalCreateNode(['type' => 'article', 'promote' => 1, 'comment' => [['status' => CommentItemInterface::CLOSED]]]);
-    $this->assertTrue($this->node, 'Article node created.');
+    $this->assertNotNull($this->node, 'Article node created.');
     $this->drupalGet('comment/reply/node/' . $this->node->id() . '/comment');
     $this->assertResponse(403);
     $this->assertNoField('edit-comment', 'Comment body field found.');
 
     // Attempt to post to node with comments enabled (check field names etc).
     $this->node = $this->drupalCreateNode(['type' => 'article', 'promote' => 1, 'comment' => [['status' => CommentItemInterface::OPEN]]]);
-    $this->assertTrue($this->node, 'Article node created.');
+    $this->assertNotNull($this->node, 'Article node created.');
     $this->drupalGet('comment/reply/node/' . $this->node->id() . '/comment');
     $this->assertNoText('This discussion is closed', 'Posting to node with comments enabled');
     $this->assertField('edit-comment-body-0-value', 'Comment body field found.');
diff --git a/core/modules/comment/tests/src/Functional/CommentNodeChangesTest.php b/core/modules/comment/tests/src/Functional/CommentNodeChangesTest.php
index 0b9fddfd3dc..52efd304b72 100644
--- a/core/modules/comment/tests/src/Functional/CommentNodeChangesTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentNodeChangesTest.php
@@ -24,9 +24,9 @@ class CommentNodeChangesTest extends CommentTestBase {
   public function testNodeDeletion() {
     $this->drupalLogin($this->webUser);
     $comment = $this->postComment($this->node, $this->randomMachineName(), $this->randomMachineName());
-    $this->assertTrue($comment->id(), 'The comment could be loaded.');
+    $this->assertInstanceOf(Comment::class, $comment, 'The comment could be loaded.');
     $this->node->delete();
-    $this->assertFalse(Comment::load($comment->id()), 'The comment could not be loaded after the node was deleted.');
+    $this->assertNull(Comment::load($comment->id()), 'The comment could not be loaded after the node was deleted.');
     // Make sure the comment field storage and all its fields are deleted when
     // the node type is deleted.
     $this->assertNotNull(FieldStorageConfig::load('node.comment'), 'Comment field storage exists');
diff --git a/core/modules/comment/tests/src/Functional/CommentNonNodeTest.php b/core/modules/comment/tests/src/Functional/CommentNonNodeTest.php
index a543510062f..0359aa01cdd 100644
--- a/core/modules/comment/tests/src/Functional/CommentNonNodeTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentNonNodeTest.php
@@ -432,7 +432,7 @@ class CommentNonNodeTest extends BrowserTestBase {
 
     // Check the field contains the correct comment type.
     $field_storage = FieldStorageConfig::load('entity_test.field_barfoo');
-    $this->assertTrue($field_storage);
+    $this->assertInstanceOf(FieldStorageConfig::class, $field_storage);
     $this->assertEqual($field_storage->getSetting('comment_type'), 'foobar');
     $this->assertEqual($field_storage->getCardinality(), 1);
 
diff --git a/core/modules/comment/tests/src/Functional/CommentTestBase.php b/core/modules/comment/tests/src/Functional/CommentTestBase.php
index 531c7076be1..245228de0dd 100644
--- a/core/modules/comment/tests/src/Functional/CommentTestBase.php
+++ b/core/modules/comment/tests/src/Functional/CommentTestBase.php
@@ -340,7 +340,7 @@ abstract class CommentTestBase extends BrowserTestBase {
    *   Contact info is available.
    */
   public function commentContactInfoAvailable() {
-    return preg_match('/(input).*?(name="name").*?(input).*?(name="mail").*?(input).*?(name="homepage")/s', $this->getSession()->getPage()->getContent());
+    return (bool) preg_match('/(input).*?(name="name").*?(input).*?(name="mail").*?(input).*?(name="homepage")/s', $this->getSession()->getPage()->getContent());
   }
 
   /**
diff --git a/core/modules/comment/tests/src/Functional/CommentTitleTest.php b/core/modules/comment/tests/src/Functional/CommentTitleTest.php
index b87b14d34d8..a6af71fd0ab 100644
--- a/core/modules/comment/tests/src/Functional/CommentTitleTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentTitleTest.php
@@ -81,7 +81,7 @@ class CommentTitleTest extends CommentTestBase {
     $comment_permalink = $this->cssSelect('.permalink');
     $comment_permalink = $comment_permalink[0]->getAttribute('href');
     // Tests that the comment's title link contains the url fragment.
-    $this->assertTrue(strpos($comment_permalink, '#comment-' . $comment1->id()), "The comment's title link contains the url fragment.");
+    $this->assertContains('#comment-' . $comment1->id(), $comment_permalink, "The comment's title link contains the url fragment.");
     $this->assertEqual($comment1->permalink()->toString(), $comment_permalink, "The comment's title has the correct link.");
   }
 
diff --git a/core/modules/comment/tests/src/Functional/CommentTypeTest.php b/core/modules/comment/tests/src/Functional/CommentTypeTest.php
index e13b2f59898..8c0b35583e3 100644
--- a/core/modules/comment/tests/src/Functional/CommentTypeTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentTypeTest.php
@@ -59,7 +59,7 @@ class CommentTypeTest extends CommentTestBase {
     $type = $this->createCommentType('other');
 
     $comment_type = CommentType::load('other');
-    $this->assertTrue($comment_type, 'The new comment type has been created.');
+    $this->assertInstanceOf(CommentType::class, $comment_type, 'The new comment type has been created.');
 
     // Log in a test user.
     $this->drupalLogin($this->adminUser);
@@ -76,7 +76,7 @@ class CommentTypeTest extends CommentTestBase {
     ];
     $this->drupalPostForm('admin/structure/comment/types/add', $edit, t('Save'));
     $comment_type = CommentType::load('foo');
-    $this->assertTrue($comment_type, 'The new comment type has been created.');
+    $this->assertInstanceOf(CommentType::class, $comment_type, 'The new comment type has been created.');
 
     // Check that the comment type was created in site default language.
     $default_langcode = \Drupal::languageManager()->getDefaultLanguage()->getId();
@@ -114,7 +114,7 @@ class CommentTypeTest extends CommentTestBase {
     $this->assertRaw('Bar', 'New name was displayed.');
     $this->clickLink('Manage fields');
     $this->assertUrl(Url::fromRoute('entity.comment.field_ui_fields', ['comment_type' => 'comment'], ['absolute' => TRUE])->toString(), [], 'Original machine name was used in URL.');
-    $this->assertTrue($this->cssSelect('tr#comment-body'), 'Body field exists.');
+    $this->assertCount(1, $this->cssSelect('tr#comment-body'), 'Body field exists.');
 
     // Remove the body field.
     $this->drupalPostForm('admin/structure/comment/manage/comment/fields/comment.comment.comment_body/delete', [], t('Delete'));
@@ -122,7 +122,7 @@ class CommentTypeTest extends CommentTestBase {
     $this->drupalPostForm('admin/structure/comment/manage/comment', [], t('Save'));
     // Check that the body field doesn't exist.
     $this->drupalGet('admin/structure/comment/manage/comment/fields');
-    $this->assertFalse($this->cssSelect('tr#comment-body'), 'Body field does not exist.');
+    $this->assertCount(0, $this->cssSelect('tr#comment-body'), 'Body field does not exist.');
   }
 
   /**
diff --git a/core/modules/comment/tests/src/Functional/Update/CommentAdminViewUpdateTest.php b/core/modules/comment/tests/src/Functional/Update/CommentAdminViewUpdateTest.php
index 01249498b63..65c36e652aa 100644
--- a/core/modules/comment/tests/src/Functional/Update/CommentAdminViewUpdateTest.php
+++ b/core/modules/comment/tests/src/Functional/Update/CommentAdminViewUpdateTest.php
@@ -39,7 +39,7 @@ class CommentAdminViewUpdateTest extends UpdatePathTestBase {
     /** @var \Drupal\views\ViewEntityInterface $comment_admin_view */
     $comment_admin_view = $entity_type_manager->getStorage('view')->load('comment');
     $this->assertNotNull($comment_admin_view, 'Comment admin view exist in storage.');
-    $this->assertTrue($comment_admin_view->enable(), 'Comment admin view is enabled.');
+    $this->assertTrue((bool) $comment_admin_view->enable()->get('status'), 'Comment admin view is enabled.');
     $comment_delete_action = $entity_type_manager->getStorage('action')->load('comment_delete_action');
     $this->assertNotNull($comment_delete_action, 'Comment delete action imported');
     // Verify comment admin page is working after updates.
diff --git a/core/modules/comment/tests/src/Functional/Views/WizardTest.php b/core/modules/comment/tests/src/Functional/Views/WizardTest.php
index 6ae5c112700..1bf53a14c4e 100644
--- a/core/modules/comment/tests/src/Functional/Views/WizardTest.php
+++ b/core/modules/comment/tests/src/Functional/Views/WizardTest.php
@@ -88,10 +88,10 @@ class WizardTest extends WizardTestBase {
     // Check for the default filters.
     $this->assertEqual($view->filter['status']->table, 'comment_field_data');
     $this->assertEqual($view->filter['status']->field, 'status');
-    $this->assertTrue($view->filter['status']->value);
+    $this->assertEquals('1', $view->filter['status']->value);
     $this->assertEqual($view->filter['status_node']->table, 'node_field_data');
     $this->assertEqual($view->filter['status_node']->field, 'status');
-    $this->assertTrue($view->filter['status_node']->value);
+    $this->assertEquals('1', $view->filter['status_node']->value);
 
     // Check for the default fields.
     $this->assertEqual($view->field['subject']->table, 'comment_field_data');
diff --git a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
index e91bbd648a3..fb823916335 100644
--- a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
+++ b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
@@ -92,7 +92,7 @@ class CommentLinksTest extends CommentViewsKernelTestBase {
 
     // Check if I can see the comment approve link on an approved comment.
     $approve_comment = $view->style_plugin->getField(1, 'approve_comment');
-    $this->assertFalse((string) $approve_comment, "Didn't find a comment approve link for an already approved comment.");
+    $this->assertEmpty((string) $approve_comment, "Didn't find a comment approve link for an already approved comment.");
 
     // Check if I can see the comment approve link on an approved comment as an
     // anonymous user.
@@ -104,7 +104,7 @@ class CommentLinksTest extends CommentViewsKernelTestBase {
     $view = Views::getView('test_comment');
     $view->preview();
     $replyto_comment = $view->style_plugin->getField(0, 'approve_comment');
-    $this->assertFalse((string) $replyto_comment, "I can't approve the comment as an anonymous user.");
+    $this->assertEmpty((string) $replyto_comment, "I can't approve the comment as an anonymous user.");
   }
 
   /**
@@ -166,7 +166,7 @@ class CommentLinksTest extends CommentViewsKernelTestBase {
 
     // Check if I can see the reply link on an unapproved comment.
     $replyto_comment = $view->style_plugin->getField(0, 'replyto_comment');
-    $this->assertFalse((string) $replyto_comment, "I can't reply to an unapproved comment.");
+    $this->assertEmpty((string) $replyto_comment, "I can't reply to an unapproved comment.");
 
     // Approve the comment.
     $comment->setPublished();
@@ -189,7 +189,7 @@ class CommentLinksTest extends CommentViewsKernelTestBase {
     $view = Views::getView('test_comment');
     $view->preview();
     $replyto_comment = $view->style_plugin->getField(0, 'replyto_comment');
-    $this->assertFalse((string) $replyto_comment, "Didn't find the comment reply link as an anonymous user.");
+    $this->assertEmpty((string) $replyto_comment, "Didn't find the comment reply link as an anonymous user.");
   }
 
 }
diff --git a/core/modules/config/tests/src/Functional/ConfigDependencyWebTest.php b/core/modules/config/tests/src/Functional/ConfigDependencyWebTest.php
index 8866d67e1d7..cce78346b71 100644
--- a/core/modules/config/tests/src/Functional/ConfigDependencyWebTest.php
+++ b/core/modules/config/tests/src/Functional/ConfigDependencyWebTest.php
@@ -72,7 +72,7 @@ class ConfigDependencyWebTest extends BrowserTestBase {
     $this->assertText($entity2->id(), 'Entity2 id found');
     $this->drupalPostForm($entity1->toUrl('delete-form'), [], 'Delete');
     $storage->resetCache();
-    $this->assertFalse($storage->loadMultiple([$entity1->id(), $entity2->id()]), 'Test entities deleted');
+    $this->assertEmpty($storage->loadMultiple([$entity1->id(), $entity2->id()]), 'Test entities deleted');
 
     // Set a more complicated test where dependencies will be fixed.
     // Entity1 will be deleted by the test.
@@ -122,12 +122,12 @@ class ConfigDependencyWebTest extends BrowserTestBase {
     $this->assertNoText($entity3->id(), 'Entity3 id not found');
     $this->drupalPostForm($entity1->toUrl('delete-form'), [], 'Delete');
     $storage->resetCache();
-    $this->assertFalse($storage->load('entity1'), 'Test entity 1 deleted');
+    $this->assertNull($storage->load('entity1'), 'Test entity 1 deleted');
     $entity2 = $storage->load('entity2');
-    $this->assertTrue($entity2, 'Entity 2 not deleted');
+    $this->assertNotEmpty($entity2, 'Entity 2 not deleted');
     $this->assertEquals([], $entity2->calculateDependencies()->getDependencies()['config'], 'Entity 2 dependencies updated to remove dependency on Entity1.');
     $entity3 = $storage->load('entity3');
-    $this->assertTrue($entity3, 'Entity 3 not deleted');
+    $this->assertNotEmpty($entity3, 'Entity 3 not deleted');
     $this->assertEquals([$entity2->getConfigDependencyName()], $entity3->calculateDependencies()->getDependencies()['config'], 'Entity 3 still depends on Entity 2.');
 
   }
diff --git a/core/modules/config/tests/src/Functional/ConfigEntityListTest.php b/core/modules/config/tests/src/Functional/ConfigEntityListTest.php
index 673223f494f..51611f78b4a 100644
--- a/core/modules/config/tests/src/Functional/ConfigEntityListTest.php
+++ b/core/modules/config/tests/src/Functional/ConfigEntityListTest.php
@@ -46,7 +46,7 @@ class ConfigEntityListTest extends BrowserTestBase {
     $controller = \Drupal::entityTypeManager()->getListBuilder('config_test');
 
     // Test getStorage() method.
-    $this->assertTrue($controller->getStorage() instanceof EntityStorageInterface, 'EntityStorage instance in storage.');
+    $this->assertInstanceOf(EntityStorageInterface::class, $controller->getStorage(), 'EntityStorage instance in storage.');
 
     // Get a list of ConfigTest entities and confirm that it contains the
     // ConfigTest entity provided by the config_test module.
@@ -54,8 +54,7 @@ class ConfigEntityListTest extends BrowserTestBase {
     $list = $controller->load();
     $this->assertCount(1, $list, '1 ConfigTest entity found.');
     $entity = $list['dotted.default'];
-    $this->assertTrue(!empty($entity), '"Default" ConfigTest entity ID found.');
-    $this->assertTrue($entity instanceof ConfigTest, '"Default" ConfigTest entity is an instance of ConfigTest.');
+    $this->assertInstanceOf(ConfigTest::class, $entity, '"Default" ConfigTest entity is an instance of ConfigTest.');
 
     // Test getOperations() method.
     $expected_operations = [
@@ -167,7 +166,7 @@ class ConfigEntityListTest extends BrowserTestBase {
 
     // Test for the table.
     $element = $this->xpath('//div[@class="layout-content"]//table');
-    $this->assertTrue($element, 'Configuration entity list table found.');
+    $this->assertCount(1, $element, 'Configuration entity list table found.');
 
     // Test the table header.
     $elements = $this->xpath('//div[@class="layout-content"]//table/thead/tr/th');
diff --git a/core/modules/config/tests/src/Functional/ConfigEntityTest.php b/core/modules/config/tests/src/Functional/ConfigEntityTest.php
index 2606ae8b92b..b1998320296 100644
--- a/core/modules/config/tests/src/Functional/ConfigEntityTest.php
+++ b/core/modules/config/tests/src/Functional/ConfigEntityTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\Tests\config\Functional;
 
 use Drupal\Component\Render\FormattableMarkup;
+use Drupal\Component\Uuid\Uuid;
 use Drupal\Core\Entity\EntityMalformedException;
 use Drupal\Core\Entity\EntityStorageException;
 use Drupal\Core\Config\Entity\ConfigEntityStorage;
@@ -42,7 +43,6 @@ class ConfigEntityTest extends BrowserTestBase {
     // Verify default properties on a newly created empty entity.
     $storage = \Drupal::entityTypeManager()->getStorage('config_test');
     $empty = $storage->create();
-    $this->assertTrue($empty->uuid());
     $this->assertIdentical($empty->label, NULL);
     $this->assertIdentical($empty->style, NULL);
     $this->assertIdentical($empty->language()->getId(), $default_langcode);
@@ -52,11 +52,11 @@ class ConfigEntityTest extends BrowserTestBase {
     $this->assertIdentical($empty->getOriginalId(), NULL);
     $this->assertIdentical($empty->bundle(), 'config_test');
     $this->assertIdentical($empty->id(), NULL);
-    $this->assertTrue($empty->uuid());
+    $this->assertTrue(Uuid::isValid($empty->uuid()));
     $this->assertIdentical($empty->label(), NULL);
 
     $this->assertIdentical($empty->get('id'), NULL);
-    $this->assertTrue($empty->get('uuid'));
+    $this->assertTrue(Uuid::isValid($empty->get('uuid')));
     $this->assertIdentical($empty->get('label'), NULL);
     $this->assertIdentical($empty->get('style'), NULL);
     $this->assertIdentical($empty->language()->getId(), $default_langcode);
@@ -100,7 +100,6 @@ class ConfigEntityTest extends BrowserTestBase {
       'label' => $this->randomString(),
       'style' => $this->randomMachineName(),
     ]);
-    $this->assertTrue($config_test->uuid());
     $this->assertNotEqual($config_test->uuid(), $empty->uuid());
     $this->assertIdentical($config_test->label, $expected['label']);
     $this->assertIdentical($config_test->style, $expected['style']);
@@ -110,7 +109,7 @@ class ConfigEntityTest extends BrowserTestBase {
     $this->assertIdentical($config_test->isNew(), TRUE);
     $this->assertIdentical($config_test->getOriginalId(), $expected['id']);
     $this->assertIdentical($config_test->id(), $expected['id']);
-    $this->assertTrue($config_test->uuid());
+    $this->assertTrue(Uuid::isValid($config_test->uuid()));
     $expected['uuid'] = $config_test->uuid();
     $this->assertIdentical($config_test->label(), $expected['label']);
 
diff --git a/core/modules/config/tests/src/Functional/ConfigImportUITest.php b/core/modules/config/tests/src/Functional/ConfigImportUITest.php
index bcad9eeb666..500a579c447 100644
--- a/core/modules/config/tests/src/Functional/ConfigImportUITest.php
+++ b/core/modules/config/tests/src/Functional/ConfigImportUITest.php
@@ -151,9 +151,7 @@ class ConfigImportUITest extends BrowserTestBase {
     $this->assertTrue(\Drupal::moduleHandler()->moduleExists('action'), 'Action module installed during import.');
     $this->assertTrue(\Drupal::moduleHandler()->moduleExists('options'), 'Options module installed during import.');
     $this->assertTrue(\Drupal::moduleHandler()->moduleExists('text'), 'Text module installed during import.');
-
-    $theme_info = \Drupal::service('theme_handler')->listInfo();
-    $this->assertTrue($theme_info['bartik']->status, 'Bartik theme installed during import.');
+    $this->assertTrue(\Drupal::service('theme_handler')->themeExists('bartik'), 'Bartik theme installed during import.');
 
     // Ensure installations and uninstallation occur as expected.
     $installed = \Drupal::state()->get('ConfigImportUITest.core.extension.modules_installed', []);
diff --git a/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php b/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php
index 1496beeb2de..52a26837e1a 100644
--- a/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php
+++ b/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\config\Functional;
 
+use Drupal\config_test\Entity\ConfigTest;
 use Drupal\Core\Config\PreExistingConfigException;
 use Drupal\Core\Config\StorageInterface;
 use Drupal\Core\File\Exception\FileException;
@@ -197,7 +198,7 @@ class ConfigInstallWebTest extends BrowserTestBase {
     $this->drupalPostForm('admin/modules', ['modules[config_other_module_config_test][enable]' => TRUE], t('Install'));
     $this->drupalPostForm('admin/modules', ['modules[config_install_dependency_test][enable]' => TRUE], t('Install'));
     $this->rebuildContainer();
-    $this->assertTrue(\Drupal::entityTypeManager()->getStorage('config_test')->load('other_module_test_with_dependency'), 'The config_test.dynamic.other_module_test_with_dependency configuration has been created during install.');
+    $this->assertInstanceOf(ConfigTest::class, \Drupal::entityTypeManager()->getStorage('config_test')->load('other_module_test_with_dependency'), 'The config_test.dynamic.other_module_test_with_dependency configuration has been created during install.');
   }
 
   /**
diff --git a/core/modules/config/tests/src/Functional/ConfigOtherModuleTest.php b/core/modules/config/tests/src/Functional/ConfigOtherModuleTest.php
index d44baf7e823..232a52114c7 100644
--- a/core/modules/config/tests/src/Functional/ConfigOtherModuleTest.php
+++ b/core/modules/config/tests/src/Functional/ConfigOtherModuleTest.php
@@ -31,7 +31,7 @@ class ConfigOtherModuleTest extends BrowserTestBase {
     // Install the module that provides the entity type. This installs the
     // default configuration.
     $this->installModule('config_test');
-    $this->assertTrue($this->getStorage()->load('other_module_test'), 'Default configuration has been installed.');
+    $this->assertNotEmpty($this->getStorage()->load('other_module_test'), 'Default configuration has been installed.');
 
     // Uninstall the module that provides the entity type. This will remove the
     // default configuration.
@@ -43,7 +43,7 @@ class ConfigOtherModuleTest extends BrowserTestBase {
     // default configuration.
     $this->installModule('config_test');
     $other_module_config_entity = $this->getStorage()->load('other_module_test');
-    $this->assertTrue($other_module_config_entity, "Default configuration has been recreated.");
+    $this->assertNotEmpty($other_module_config_entity, "Default configuration has been recreated.");
 
     // Update the default configuration to test that the changes are preserved
     // if the module that provides the default configuration is uninstalled.
@@ -52,10 +52,10 @@ class ConfigOtherModuleTest extends BrowserTestBase {
 
     // Uninstall the module that provides the default configuration.
     $this->uninstallModule('config_other_module_config_test');
-    $this->assertTrue($this->getStorage()->load('other_module_test'), 'Default configuration for other modules is not removed when the module that provides it is uninstalled.');
+    $this->assertNotEmpty($this->getStorage()->load('other_module_test'), 'Default configuration for other modules is not removed when the module that provides it is uninstalled.');
 
     // Default configuration provided by config_test should still exist.
-    $this->assertTrue($this->getStorage()->load('dotted.default'), 'The configuration is not deleted.');
+    $this->assertNotEmpty($this->getStorage()->load('dotted.default'), 'The configuration is not deleted.');
 
     // Re-enable module to test that pre-existing optional configuration does
     // not throw an error.
@@ -68,12 +68,12 @@ class ConfigOtherModuleTest extends BrowserTestBase {
     $this->assertNull($this->getStorage()->load('other_module_test_optional_entity_unmet'), 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet whose dependencies are not met is not created.');    $this->installModule('config_test_language');
     $this->assertNull($this->getStorage()->load('other_module_test_optional_entity_unmet'), 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet whose dependencies are met is not created.');
     $this->installModule('config_install_dependency_test');
-    $this->assertTrue($this->getStorage()->load('other_module_test_unmet'), 'The optional configuration config_test.dynamic.other_module_test_unmet whose dependencies are met is now created.');
+    $this->assertNotEmpty($this->getStorage()->load('other_module_test_unmet'), 'The optional configuration config_test.dynamic.other_module_test_unmet whose dependencies are met is now created.');
     // The following configuration entity's dependencies are now met. It is
     // indirectly dependent on the config_install_dependency_test module because
     // it has a dependency on the config_test.dynamic.dependency_for_unmet2
     // configuration provided by that module and, therefore, should be created.
-    $this->assertTrue($this->getStorage()->load('other_module_test_optional_entity_unmet2'), 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet2 whose dependencies are met is now created.');
+    $this->assertNotEmpty($this->getStorage()->load('other_module_test_optional_entity_unmet2'), 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet2 whose dependencies are met is now created.');
 
     // The following configuration entity's dependencies are now met even though
     // it has no direct dependency on the module. It is indirectly dependent on
@@ -82,13 +82,13 @@ class ConfigOtherModuleTest extends BrowserTestBase {
     // dependent on the config_install_dependency_test module and, therefore,
     // should be created.
     $entity = $this->getStorage()->load('other_module_test_optional_entity_unmet');
-    $this->assertTrue($entity, 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet whose dependencies are met is created.');
+    $this->assertNotEmpty($entity, 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet whose dependencies are met is created.');
     $entity->delete();
 
     // Install another module to ensure the configuration just deleted is not
     // recreated.
     $this->installModule('config');
-    $this->assertFalse($this->getStorage()->load('other_module_test_optional_entity_unmet'), 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet whose dependencies are met is not installed when an unrelated module is installed.');
+    $this->assertNull($this->getStorage()->load('other_module_test_optional_entity_unmet'), 'The optional configuration config_test.dynamic.other_module_test_optional_entity_unmet whose dependencies are met is not installed when an unrelated module is installed.');
   }
 
   /**
@@ -96,10 +96,10 @@ class ConfigOtherModuleTest extends BrowserTestBase {
    */
   public function testInstallConfigEntityModuleFirst() {
     $this->installModule('config_test');
-    $this->assertFalse($this->getStorage()->load('other_module_test'), 'Default configuration provided by config_other_module_config_test does not exist.');
+    $this->assertNull($this->getStorage()->load('other_module_test'), 'Default configuration provided by config_other_module_config_test does not exist.');
 
     $this->installModule('config_other_module_config_test');
-    $this->assertTrue($this->getStorage()->load('other_module_test'), 'Default configuration provided by config_other_module_config_test has been installed.');
+    $this->assertNotEmpty($this->getStorage()->load('other_module_test'), 'Default configuration provided by config_other_module_config_test has been installed.');
   }
 
   /**
diff --git a/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php b/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php
index bb5e218191a..097262a46ba 100644
--- a/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php
+++ b/core/modules/config_translation/tests/src/Functional/ConfigTranslationUiTest.php
@@ -1165,10 +1165,8 @@ class ConfigTranslationUiTest extends BrowserTestBase {
     ]));
     // Make sure the text format select is not shown.
     $select_id = str_replace('value', 'format--2', $id);
-    $select = $this->xpath('//select[@id=:id]', [':id' => $select_id]);
-    return $this->assertFalse($select, new FormattableMarkup('Field @id does not exist.', [
-      '@id' => $id,
-    ]));
+    $xpath = $this->assertSession()->buildXPathQuery('//select[@id=:id]', [':id' => $select_id]);
+    $this->assertSession()->elementNotExists('xpath', $xpath);
   }
 
   /**
diff --git a/core/modules/contact/tests/src/Functional/ContactPersonalTest.php b/core/modules/contact/tests/src/Functional/ContactPersonalTest.php
index 680d1239db3..d21e8e2b549 100644
--- a/core/modules/contact/tests/src/Functional/ContactPersonalTest.php
+++ b/core/modules/contact/tests/src/Functional/ContactPersonalTest.php
@@ -215,10 +215,10 @@ class ContactPersonalTest extends BrowserTestBase {
     // form.
     $this->drupalGet('user/' . $this->webUser->id() . '/edit');
     $this->assertNoFieldChecked('edit-contact--2');
-    $this->assertFalse(\Drupal::service('user.data')->get('contact', $this->webUser->id(), 'enabled'), 'Personal contact form disabled');
+    $this->assertNull(\Drupal::service('user.data')->get('contact', $this->webUser->id(), 'enabled'), 'Personal contact form disabled');
     $this->drupalPostForm(NULL, ['contact' => TRUE], t('Save'));
     $this->assertFieldChecked('edit-contact--2');
-    $this->assertTrue(\Drupal::service('user.data')->get('contact', $this->webUser->id(), 'enabled'), 'Personal contact form enabled');
+    $this->assertNotEmpty(\Drupal::service('user.data')->get('contact', $this->webUser->id(), 'enabled'), 'Personal contact form enabled');
 
     // Test with disabled global default contact form in combination with a user
     // that has the contact form enabled.
diff --git a/core/modules/contact/tests/src/Functional/ContactSitewideTest.php b/core/modules/contact/tests/src/Functional/ContactSitewideTest.php
index 5093a545c5b..7960c2dcb5f 100644
--- a/core/modules/contact/tests/src/Functional/ContactSitewideTest.php
+++ b/core/modules/contact/tests/src/Functional/ContactSitewideTest.php
@@ -55,10 +55,10 @@ class ContactSitewideTest extends BrowserTestBase {
     $this->drupalGet('contact');
 
     // Ensure that there is no textfield for name.
-    $this->assertFalse($this->xpath('//input[@name=:name]', [':name' => 'name']));
+    $this->assertEmpty($this->xpath('//input[@name=:name]', [':name' => 'name']));
 
     // Ensure that there is no textfield for email.
-    $this->assertFalse($this->xpath('//input[@name=:name]', [':name' => 'mail']));
+    $this->assertEmpty($this->xpath('//input[@name=:name]', [':name' => 'mail']));
 
     // Logout and retrieve the page as an anonymous user
     $this->drupalLogout();
@@ -66,10 +66,10 @@ class ContactSitewideTest extends BrowserTestBase {
     $this->drupalGet('contact');
 
     // Ensure that there is textfield for name.
-    $this->assertTrue($this->xpath('//input[@name=:name]', [':name' => 'name']));
+    $this->assertNotEmpty($this->xpath('//input[@name=:name]', [':name' => 'name']));
 
     // Ensure that there is textfield for email.
-    $this->assertTrue($this->xpath('//input[@name=:name]', [':name' => 'mail']));
+    $this->assertNotEmpty($this->xpath('//input[@name=:name]', [':name' => 'mail']));
 
     // Create and log in administrative user.
     $admin_user = $this->drupalCreateUser([
@@ -329,8 +329,8 @@ class ContactSitewideTest extends BrowserTestBase {
     $mails = $this->getMails();
     $mail = array_pop($mails);
     $this->assertEqual($mail['subject'], t('[@label] @subject', ['@label' => $label, '@subject' => $edit['subject[0][value]']]));
-    $this->assertTrue(strpos($mail['body'], $field_label));
-    $this->assertTrue(strpos($mail['body'], $edit[$field_name . '[0][value]']));
+    $this->assertContains($field_label, $mail['body']);
+    $this->assertContains($edit[$field_name . '[0][value]'], $mail['body']);
 
     // Test messages and redirect.
     /** @var \Drupal\contact\ContactFormInterface $form */
@@ -573,7 +573,7 @@ class ContactSitewideTest extends BrowserTestBase {
       else {
         $this->drupalPostForm("admin/structure/contact/manage/$id/delete", [], t('Delete'));
         $this->assertRaw(t('The contact form %label has been deleted.', ['%label' => $contact_form->label()]));
-        $this->assertFalse(ContactForm::load($id), new FormattableMarkup('Form %contact_form not found', ['%contact_form' => $contact_form->label()]));
+        $this->assertNull(ContactForm::load($id), new FormattableMarkup('Form %contact_form not found', ['%contact_form' => $contact_form->label()]));
       }
     }
   }
diff --git a/core/modules/contact/tests/src/Functional/Update/ContactUpdateTest.php b/core/modules/contact/tests/src/Functional/Update/ContactUpdateTest.php
index f094ea47dc4..607fbfe56b4 100644
--- a/core/modules/contact/tests/src/Functional/Update/ContactUpdateTest.php
+++ b/core/modules/contact/tests/src/Functional/Update/ContactUpdateTest.php
@@ -31,7 +31,7 @@ class ContactUpdateTest extends UpdatePathTestBase {
     $config_factory = \Drupal::configFactory();
     // Check that contact_form entities are more than zero.
     $contact_forms = $config_factory->listAll('contact.form.');
-    $this->assertTrue(count($contact_forms), 'There are contact forms to update.');
+    $this->assertGreaterThan(0, count($contact_forms), 'There are contact forms to update.');
     foreach ($contact_forms as $contact_config_name) {
       $contact_form_data = $config_factory->get($contact_config_name)->get();
       $this->assertFalse(isset($contact_form_data['message']), 'Prior to running the update the "message" key does not exist.');
diff --git a/core/modules/contact/tests/src/Functional/Views/ContactLinkTest.php b/core/modules/contact/tests/src/Functional/Views/ContactLinkTest.php
index f277e08bae7..6ab1f1fc205 100644
--- a/core/modules/contact/tests/src/Functional/Views/ContactLinkTest.php
+++ b/core/modules/contact/tests/src/Functional/Views/ContactLinkTest.php
@@ -106,7 +106,7 @@ class ContactLinkTest extends ViewTestBase {
       $account = $accounts[$name];
 
       $result = $this->xpath('//div[contains(@class, "views-field-contact")]//a[contains(@href, :url)]', [':url' => $account->toUrl('contact-form')->toString()]);
-      $this->assertTrue(count($result));
+      $this->assertGreaterThan(0, count($result));
     }
   }
 
diff --git a/core/modules/contact/tests/src/Kernel/Views/ContactFieldsTest.php b/core/modules/contact/tests/src/Kernel/Views/ContactFieldsTest.php
index 374013013a2..ae83c46e87a 100644
--- a/core/modules/contact/tests/src/Kernel/Views/ContactFieldsTest.php
+++ b/core/modules/contact/tests/src/Kernel/Views/ContactFieldsTest.php
@@ -52,7 +52,7 @@ class ContactFieldsTest extends KernelTestBase {
     // entities have no storage.
     $table_name = 'contact_message__' . $field_name;
     $data = $this->container->get('views.views_data')->get($table_name);
-    $this->assertFalse($data);
+    $this->assertEmpty($data);
   }
 
 }
diff --git a/core/modules/content_moderation/tests/src/Functional/ModerationFormTest.php b/core/modules/content_moderation/tests/src/Functional/ModerationFormTest.php
index 4774f284b00..e825682d204 100644
--- a/core/modules/content_moderation/tests/src/Functional/ModerationFormTest.php
+++ b/core/modules/content_moderation/tests/src/Functional/ModerationFormTest.php
@@ -301,10 +301,10 @@ class ModerationFormTest extends ModerationStateTestBase {
       'body[0][value]' => 'First version of the content.',
       'moderation_state[0][state]' => 'draft',
     ], t('Save'));
-    $this->assertTrue($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertNotEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     $node = $this->drupalGetNodeByTitle('Some moderated content');
-    $this->assertTrue($node->language(), 'en');
+    $this->assertNotEmpty($node->language(), 'en');
     $edit_path = sprintf('node/%d/edit', $node->id());
     $translate_path = sprintf('node/%d/translations/add/en/fr', $node->id());
     $latest_version_path = sprintf('node/%d/latest', $node->id());
@@ -312,7 +312,7 @@ class ModerationFormTest extends ModerationStateTestBase {
 
     $this->drupalGet($latest_version_path);
     $this->assertSession()->statusCodeEquals('403');
-    $this->assertFalse($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     // Add french translation (revision 2).
     $this->drupalGet($translate_path);
@@ -326,7 +326,7 @@ class ModerationFormTest extends ModerationStateTestBase {
 
     $this->drupalGet($latest_version_path, ['language' => $french]);
     $this->assertSession()->statusCodeEquals('403');
-    $this->assertFalse($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     // Add french pending revision (revision 3).
     $this->drupalGet($edit_path, ['language' => $french]);
@@ -349,14 +349,14 @@ class ModerationFormTest extends ModerationStateTestBase {
     ], t('Save (this translation)'));
 
     $this->drupalGet($latest_version_path, ['language' => $french]);
-    $this->assertTrue($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertNotEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     $this->drupalGet($edit_path);
     $this->clickLink('Delete');
     $this->assertSession()->buttonExists('Delete');
 
     $this->drupalGet($latest_version_path);
-    $this->assertFalse($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     // Publish the french pending revision (revision 4).
     $this->drupalGet($edit_path, ['language' => $french]);
@@ -369,7 +369,7 @@ class ModerationFormTest extends ModerationStateTestBase {
     ], t('Save (this translation)'));
 
     $this->drupalGet($latest_version_path, ['language' => $french]);
-    $this->assertFalse($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     // Publish the English pending revision (revision 5).
     $this->drupalGet($edit_path);
@@ -382,7 +382,7 @@ class ModerationFormTest extends ModerationStateTestBase {
     ], t('Save (this translation)'));
 
     $this->drupalGet($latest_version_path);
-    $this->assertFalse($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     // Make sure we are allowed to create a pending French revision.
     $this->drupalGet($edit_path, ['language' => $french]);
@@ -401,9 +401,9 @@ class ModerationFormTest extends ModerationStateTestBase {
     ], t('Save (this translation)'));
 
     $this->drupalGet($latest_version_path);
-    $this->assertTrue($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertNotEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
     $this->drupalGet($latest_version_path, ['language' => $french]);
-    $this->assertFalse($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     // Publish the English pending revision (revision 7)
     $this->drupalGet($edit_path);
@@ -416,7 +416,7 @@ class ModerationFormTest extends ModerationStateTestBase {
     ], t('Save (this translation)'));
 
     $this->drupalGet($latest_version_path);
-    $this->assertFalse($this->xpath('//ul[@class="entity-moderation-form"]'));
+    $this->assertEmpty($this->xpath('//ul[@class="entity-moderation-form"]'));
 
     // Make sure we are allowed to create a pending French revision.
     $this->drupalGet($edit_path, ['language' => $french]);
@@ -437,7 +437,7 @@ class ModerationFormTest extends ModerationStateTestBase {
     ], t('Save'));
 
     $node = $this->drupalGetNodeByTitle('Third moderated content');
-    $this->assertTrue($node->language(), 'en');
+    $this->assertNotEmpty($node->language(), 'en');
     $edit_path = sprintf('node/%d/edit', $node->id());
     $translate_path = sprintf('node/%d/translations/add/en/fr', $node->id());
 
diff --git a/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php b/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php
index fcf4d06c449..eadfa65f528 100644
--- a/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php
+++ b/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php
@@ -184,7 +184,7 @@ class ContentModerationStateTest extends KernelTestBase {
     $entity = $this->reloadEntity($entity);
     $entity->delete();
     $content_moderation_state = ContentModerationState::loadFromModeratedEntity($entity);
-    $this->assertFalse($content_moderation_state);
+    $this->assertNull($content_moderation_state);
   }
 
   /**
@@ -233,13 +233,13 @@ class ContentModerationStateTest extends KernelTestBase {
     $entity->save();
 
     $content_moderation_state = ContentModerationState::loadFromModeratedEntity($entity);
-    $this->assertTrue($content_moderation_state);
+    $this->assertNotEmpty($content_moderation_state);
 
     $entity_storage = $this->entityTypeManager->getStorage($entity_type_id);
     $entity_storage->deleteRevision($entity->getRevisionId());
 
     $content_moderation_state = ContentModerationState::loadFromModeratedEntity($entity);
-    $this->assertFalse($content_moderation_state);
+    $this->assertNull($content_moderation_state);
   }
 
   /**
diff --git a/core/modules/content_translation/tests/src/Functional/ContentTranslationLinkTagTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationLinkTagTest.php
index 2e77e70cb6e..905e26146b3 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTranslationLinkTagTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationLinkTagTest.php
@@ -136,7 +136,7 @@ class ContentTranslationLinkTagTest extends BrowserTestBase {
 
     $this->assertSession()->statusCodeEquals(200);
     $result = $this->xpath('//link[@rel="alternate" and @hreflang]');
-    $this->assertFalse($result, 'No alternate link tag found.');
+    $this->assertEmpty($result, 'No alternate link tag found.');
   }
 
 }
diff --git a/core/modules/content_translation/tests/src/Functional/ContentTranslationSettingsTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationSettingsTest.php
index 4708fe8146c..77b3c697b0f 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTranslationSettingsTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationSettingsTest.php
@@ -82,7 +82,7 @@ class ContentTranslationSettingsTest extends BrowserTestBase {
     ];
     $this->assertSettings('comment', 'comment_article', FALSE, $edit);
     $xpath_err = '//div[contains(@class, "error")]';
-    $this->assertTrue($this->xpath($xpath_err), 'Enabling translation only for entity bundles generates a form error.');
+    $this->assertNotEmpty($this->xpath($xpath_err), 'Enabling translation only for entity bundles generates a form error.');
 
     // Test that the translation settings are not stored if a non-configurable
     // language is set as default and the language selector is hidden.
@@ -94,7 +94,7 @@ class ContentTranslationSettingsTest extends BrowserTestBase {
       'settings[comment][comment_article][fields][comment_body]' => TRUE,
     ];
     $this->assertSettings('comment', 'comment_article', FALSE, $edit);
-    $this->assertTrue($this->xpath($xpath_err), 'Enabling translation with a fixed non-configurable language generates a form error.');
+    $this->assertNotEmpty($this->xpath($xpath_err), 'Enabling translation with a fixed non-configurable language generates a form error.');
 
     // Test that a field shared among different bundles can be enabled without
     // needing to make all the related bundles translatable.
diff --git a/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
index 899d1ada68f..8e5734cd82e 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
@@ -117,7 +117,7 @@ class ContentTranslationSyncImageTest extends ContentTranslationTestBase {
     ];
     $this->drupalPostForm('admin/config/regional/content-language', $edit, t('Save configuration'));
     $errors = $this->xpath('//div[contains(@class, "messages--error")]');
-    $this->assertFalse($errors, 'Settings correctly stored.');
+    $this->assertEmpty($errors, 'Settings correctly stored.');
     $this->assertFieldChecked('edit-settings-entity-test-mul-entity-test-mul-columns-field-test-et-ui-image-alt');
     $this->assertFieldChecked('edit-settings-entity-test-mul-entity-test-mul-columns-field-test-et-ui-image-title');
     $this->drupalLogin($this->translator);
diff --git a/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
index 617d816af0b..5e7954086fb 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationUITestBase.php
@@ -81,7 +81,7 @@ abstract class ContentTranslationUITestBase extends ContentTranslationTestBase {
       ->getStorage($this->entityTypeId);
     $storage->resetCache([$this->entityId]);
     $entity = $storage->load($this->entityId);
-    $this->assertTrue($entity, 'Entity found in the database.');
+    $this->assertNotEmpty($entity, 'Entity found in the database.');
     $this->drupalGet($entity->toUrl());
     $this->assertResponse(200, 'Entity URL is valid.');
 
@@ -257,11 +257,11 @@ abstract class ContentTranslationUITestBase extends ContentTranslationTestBase {
       $this->drupalGet($url);
       if ($added_langcode == $langcode) {
         $this->assertFieldByXPath('//input[@name="content_translation[retranslate]"]', FALSE, 'The retranslate flag is not checked by default.');
-        $this->assertFalse($this->xpath('//details[@id="edit-content-translation" and @open="open"]'), 'The translation tab should be collapsed by default.');
+        $this->assertEmpty($this->xpath('//details[@id="edit-content-translation" and @open="open"]'), 'The translation tab should be collapsed by default.');
       }
       else {
         $this->assertFieldByXPath('//input[@name="content_translation[outdated]"]', TRUE, 'The translate flag is checked by default.');
-        $this->assertTrue($this->xpath('//details[@id="edit-content-translation" and @open="open"]'), 'The translation tab is correctly expanded when the translation is outdated.');
+        $this->assertNotEmpty($this->xpath('//details[@id="edit-content-translation" and @open="open"]'), 'The translation tab is correctly expanded when the translation is outdated.');
         $edit = ['content_translation[outdated]' => FALSE];
         $this->drupalPostForm($url, $edit, $this->getFormSubmitAction($entity, $added_langcode));
         $this->drupalGet($url);
@@ -346,7 +346,7 @@ abstract class ContentTranslationUITestBase extends ContentTranslationTestBase {
       'content_translation[created]' => '19/11/1978',
     ];
     $this->drupalPostForm($entity->toUrl('edit-form'), $edit, $this->getFormSubmitAction($entity, $langcode));
-    $this->assertTrue($this->xpath('//div[contains(@class, "error")]//ul'), 'Invalid values generate a list of form errors.');
+    $this->assertNotEmpty($this->xpath('//div[contains(@class, "error")]//ul'), 'Invalid values generate a list of form errors.');
     $metadata = $this->manager->getTranslationMetadata($entity->getTranslation($langcode));
     $this->assertEqual($metadata->getAuthor()->id(), $values[$langcode]['uid'], 'Translation author correctly kept.');
     $this->assertEqual($metadata->getCreatedTime(), $values[$langcode]['created'], 'Translation date correctly kept.');
diff --git a/core/modules/dblog/tests/src/Functional/DbLogTest.php b/core/modules/dblog/tests/src/Functional/DbLogTest.php
index ee08a290012..d12f88b1a1e 100644
--- a/core/modules/dblog/tests/src/Functional/DbLogTest.php
+++ b/core/modules/dblog/tests/src/Functional/DbLogTest.php
@@ -187,7 +187,7 @@ class DbLogTest extends BrowserTestBase {
 
     // Check row limit variable.
     $current_limit = $this->config('dblog.settings')->get('row_limit');
-    $this->assertTrue($current_limit == $row_limit, new FormattableMarkup('[Cache] Row limit variable of @count equals row limit of @limit', ['@count' => $current_limit, '@limit' => $row_limit]));
+    $this->assertEquals($current_limit, $row_limit, new FormattableMarkup('[Cache] Row limit variable of @count equals row limit of @limit', ['@count' => $current_limit, '@limit' => $row_limit]));
   }
 
   /**
@@ -346,7 +346,7 @@ class DbLogTest extends BrowserTestBase {
     $this->assertResponse(200);
     // Retrieve the user object.
     $user = user_load_by_name($name);
-    $this->assertTrue($user != NULL, new FormattableMarkup('User @name was loaded', ['@name' => $name]));
+    $this->assertNotNull($user, new FormattableMarkup('User @name was loaded', ['@name' => $name]));
     // pass_raw property is needed by drupalLogin.
     $user->passRaw = $pass;
     // Log in user.
@@ -359,7 +359,7 @@ class DbLogTest extends BrowserTestBase {
       $ids[] = $row->wid;
     }
     $count_before = (isset($ids)) ? count($ids) : 0;
-    $this->assertTrue($count_before > 0, new FormattableMarkup('DBLog contains @count records for @name', ['@count' => $count_before, '@name' => $user->getAccountName()]));
+    $this->assertGreaterThan(0, $count_before, new FormattableMarkup('DBLog contains @count records for @name', ['@count' => $count_before, '@name' => $user->getAccountName()]));
 
     // Log in the admin user.
     $this->drupalLogin($this->adminUser);
@@ -396,7 +396,7 @@ class DbLogTest extends BrowserTestBase {
       // Check for full message text on the details page.
       $this->assertRaw($message, 'DBLog event details was found: [delete user]');
     }
-    $this->assertTrue($link, 'DBLog event was recorded: [delete user]');
+    $this->assertNotEmpty($link, 'DBLog event was recorded: [delete user]');
     // Visit random URL (to generate page not found event).
     $not_found_url = $this->randomMachineName(60);
     $this->drupalGet($not_found_url);
@@ -429,7 +429,7 @@ class DbLogTest extends BrowserTestBase {
     $this->assertResponse(200);
     // Retrieve the node object.
     $node = $this->drupalGetNodeByTitle($title);
-    $this->assertTrue($node != NULL, new FormattableMarkup('Node @title was loaded', ['@title' => $title]));
+    $this->assertNotNull($node, new FormattableMarkup('Node @title was loaded', ['@title' => $title]));
     // Edit the node.
     $edit = $this->getContentUpdate($type);
     $this->drupalPostForm('node/' . $node->id() . '/edit', $edit, t('Save'));
diff --git a/core/modules/dblog/tests/src/Kernel/ConnectionFailureTest.php b/core/modules/dblog/tests/src/Kernel/ConnectionFailureTest.php
index 28a603f56a9..4914f9f4c9a 100644
--- a/core/modules/dblog/tests/src/Kernel/ConnectionFailureTest.php
+++ b/core/modules/dblog/tests/src/Kernel/ConnectionFailureTest.php
@@ -40,7 +40,7 @@ class ConnectionFailureTest extends KernelTestBase {
     $database = Database::getConnection();
 
     $wid = $database->query("SELECT MAX(wid) FROM {watchdog} WHERE message = 'testConnectionFailureLogging'")->fetchField();
-    $this->assertTrue($wid);
+    $this->assertNotEmpty($wid, 'Watchdog entry has been stored in database.');
   }
 
 }
diff --git a/core/modules/dynamic_page_cache/tests/src/Functional/DynamicPageCacheIntegrationTest.php b/core/modules/dynamic_page_cache/tests/src/Functional/DynamicPageCacheIntegrationTest.php
index 1574679c24c..03e0386636d 100644
--- a/core/modules/dynamic_page_cache/tests/src/Functional/DynamicPageCacheIntegrationTest.php
+++ b/core/modules/dynamic_page_cache/tests/src/Functional/DynamicPageCacheIntegrationTest.php
@@ -56,7 +56,7 @@ class DynamicPageCacheIntegrationTest extends BrowserTestBase {
     // Cache.
     $url = Url::fromUri('route:dynamic_page_cache_test.response');
     $this->drupalGet($url);
-    $this->assertFalse($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response object returned: Dynamic Page Cache is ignoring.');
+    $this->assertNull($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response object returned: Dynamic Page Cache is ignoring.');
 
     // Controllers returning CacheableResponseInterface (cacheable response)
     // objects are handled by Dynamic Page Cache.
@@ -100,19 +100,19 @@ class DynamicPageCacheIntegrationTest extends BrowserTestBase {
     // response, are ignored by Dynamic Page Cache (but only because those
     // wrapper formats' responses do not implement CacheableResponseInterface).
     $this->drupalGet('dynamic-page-cache-test/html', ['query' => [MainContentViewSubscriber::WRAPPER_FORMAT => 'drupal_ajax']]);
-    $this->assertFalse($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Render array returned, rendered as AJAX response: Dynamic Page Cache is ignoring.');
+    $this->assertNull($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Render array returned, rendered as AJAX response: Dynamic Page Cache is ignoring.');
     $this->drupalGet('dynamic-page-cache-test/html', ['query' => [MainContentViewSubscriber::WRAPPER_FORMAT => 'drupal_dialog']]);
-    $this->assertFalse($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Render array returned, rendered as dialog response: Dynamic Page Cache is ignoring.');
+    $this->assertNull($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Render array returned, rendered as dialog response: Dynamic Page Cache is ignoring.');
     $this->drupalGet('dynamic-page-cache-test/html', ['query' => [MainContentViewSubscriber::WRAPPER_FORMAT => 'drupal_modal']]);
-    $this->assertFalse($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Render array returned, rendered as modal response: Dynamic Page Cache is ignoring.');
+    $this->assertNull($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Render array returned, rendered as modal response: Dynamic Page Cache is ignoring.');
 
     // Admin routes are ignored by Dynamic Page Cache.
     $this->drupalGet('dynamic-page-cache-test/html/admin');
-    $this->assertFalse($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response returned, rendered as HTML response, admin route: Dynamic Page Cache is ignoring');
+    $this->assertNull($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response returned, rendered as HTML response, admin route: Dynamic Page Cache is ignoring');
     $this->drupalGet('dynamic-page-cache-test/response/admin');
-    $this->assertFalse($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response returned, plain response, admin route: Dynamic Page Cache is ignoring');
+    $this->assertNull($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response returned, plain response, admin route: Dynamic Page Cache is ignoring');
     $this->drupalGet('dynamic-page-cache-test/cacheable-response/admin');
-    $this->assertFalse($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response returned, cacheable response, admin route: Dynamic Page Cache is ignoring');
+    $this->assertNull($this->drupalGetHeader(DynamicPageCacheSubscriber::HEADER), 'Response returned, cacheable response, admin route: Dynamic Page Cache is ignoring');
 
     // Max-age = 0 responses are ignored by Dynamic Page Cache.
     $this->drupalGet('dynamic-page-cache-test/html/uncacheable/max-age');
diff --git a/core/modules/editor/tests/src/Functional/EditorAdminTest.php b/core/modules/editor/tests/src/Functional/EditorAdminTest.php
index 780fa3b145e..618911fcb0c 100644
--- a/core/modules/editor/tests/src/Functional/EditorAdminTest.php
+++ b/core/modules/editor/tests/src/Functional/EditorAdminTest.php
@@ -211,7 +211,7 @@ class EditorAdminTest extends BrowserTestBase {
     ];
     $this->drupalPostForm(NULL, $edit, 'Configure');
     $unicorn_setting = $this->xpath('//input[@name="editor[settings][ponies_too]" and @type="checkbox" and @checked]');
-    $this->assertTrue(count($unicorn_setting), "Unicorn Editor's settings form is present.");
+    $this->assertCount(1, $unicorn_setting, "Unicorn Editor's settings form is present.");
 
     return $edit;
   }
diff --git a/core/modules/editor/tests/src/Functional/EditorDialogAccessTest.php b/core/modules/editor/tests/src/Functional/EditorDialogAccessTest.php
index 46a41a6a722..c317366ec9c 100644
--- a/core/modules/editor/tests/src/Functional/EditorDialogAccessTest.php
+++ b/core/modules/editor/tests/src/Functional/EditorDialogAccessTest.php
@@ -70,8 +70,8 @@ class EditorDialogAccessTest extends BrowserTestBase {
     $editor->save();
     $this->resetAll();
     $this->drupalGet($url);
-    $this->assertTrue($this->cssSelect('input[type=text][name="attributes[src]"]'), 'Image uploads disabled: input[type=text][name="attributes[src]"] is present.');
-    $this->assertFalse($this->cssSelect('input[type=file]'), 'Image uploads disabled: input[type=file] is absent.');
+    $this->assertNotEmpty($this->cssSelect('input[type=text][name="attributes[src]"]'), 'Image uploads disabled: input[type=text][name="attributes[src]"] is present.');
+    $this->assertEmpty($this->cssSelect('input[type=file]'), 'Image uploads disabled: input[type=file] is absent.');
     $session->statusCodeEquals(200);
 
     // With image upload settings, expect a 200, and now there should be an
@@ -80,8 +80,8 @@ class EditorDialogAccessTest extends BrowserTestBase {
       ->save();
     $this->resetAll();
     $this->drupalGet($url);
-    $this->assertFalse($this->cssSelect('input[type=text][name="attributes[src]"]'), 'Image uploads enabled: input[type=text][name="attributes[src]"] is absent.');
-    $this->assertTrue($this->cssSelect('input[type=file]'), 'Image uploads enabled: input[type=file] is present.');
+    $this->assertEmpty($this->cssSelect('input[type=text][name="attributes[src]"]'), 'Image uploads enabled: input[type=text][name="attributes[src]"] is absent.');
+    $this->assertNotEmpty($this->cssSelect('input[type=file]'), 'Image uploads enabled: input[type=file] is present.');
     $session->statusCodeEquals(200);
   }
 
diff --git a/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceAutoCreateTest.php b/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceAutoCreateTest.php
index 0e5deb0324c..831775380d3 100644
--- a/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceAutoCreateTest.php
+++ b/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceAutoCreateTest.php
@@ -114,7 +114,7 @@ class EntityReferenceAutoCreateTest extends BrowserTestBase {
 
     $query = clone $base_query;
     $result = $query->execute();
-    $this->assertFalse($result, 'Referenced node does not exist yet.');
+    $this->assertEmpty($result, 'Referenced node does not exist yet.');
 
     $edit = [
       'title[0][value]' => $this->randomMachineName(),
@@ -125,7 +125,7 @@ class EntityReferenceAutoCreateTest extends BrowserTestBase {
     // Assert referenced node was created.
     $query = clone $base_query;
     $result = $query->execute();
-    $this->assertTrue($result, 'Referenced node was created.');
+    $this->assertNotEmpty($result, 'Referenced node was created.');
     $referenced_nid = key($result);
     $referenced_node = Node::load($referenced_nid);
 
diff --git a/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php b/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php
index 9cc161396ed..b841d502f9f 100644
--- a/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php
+++ b/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php
@@ -193,7 +193,7 @@ class EntityReferenceIntegrationTest extends BrowserTestBase {
     $entity = current($this->container->get('entity_type.manager')->getStorage(
     $this->entityType)->loadByProperties(['name' => $entity_name]));
 
-    $this->assertTrue($entity, new FormattableMarkup('%entity_type: Entity found in the database.', ['%entity_type' => $this->entityType]));
+    $this->assertNotEmpty($entity, new FormattableMarkup('%entity_type: Entity found in the database.', ['%entity_type' => $this->entityType]));
 
     $this->assertEqual($entity->{$this->fieldName}->target_id, $referenced_entities[0]->id());
     $this->assertEqual($entity->{$this->fieldName}->entity->id(), $referenced_entities[0]->id());
diff --git a/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php b/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php
index 6641d691f9a..1307422bc04 100644
--- a/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php
+++ b/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php
@@ -114,7 +114,7 @@ class FieldImportDeleteUninstallUiTest extends FieldTestBase {
     $this->assertNoText('Field data will be deleted by this synchronization.');
     $this->rebuildContainer();
     $this->assertFalse(\Drupal::moduleHandler()->moduleExists('telephone'));
-    $this->assertFalse(\Drupal::service('entity.repository')->loadEntityByUuid('field_storage_config', $field_storage->uuid()), 'The telephone field has been deleted by the configuration synchronization');
+    $this->assertNull(\Drupal::service('entity.repository')->loadEntityByUuid('field_storage_config', $field_storage->uuid()), 'The telephone field has been deleted by the configuration synchronization');
     $deleted_storages = \Drupal::state()->get('field.storage.deleted') ?: [];
     $this->assertFalse(isset($deleted_storages[$field_storage->uuid()]), 'Telephone field has been completed removed from the system.');
     $this->assertFalse(isset($deleted_storages[$field_storage->uuid()]), 'Text field has been completed removed from the system.');
diff --git a/core/modules/field/tests/src/Functional/NestedFormTest.php b/core/modules/field/tests/src/Functional/NestedFormTest.php
index 31af3d48566..0a646e3d5c1 100644
--- a/core/modules/field/tests/src/Functional/NestedFormTest.php
+++ b/core/modules/field/tests/src/Functional/NestedFormTest.php
@@ -127,14 +127,14 @@ class NestedFormTest extends FieldTestBase {
     $this->drupalPostForm('test-entity/nested/1/2', $edit, t('Save'));
     $this->assertRaw(t('%label does not accept the value -1', ['%label' => 'Unlimited field']), 'Entity 1: the field validation error was reported.');
     $error_field = $this->xpath('//input[@id=:id and contains(@class, "error")]', [':id' => 'edit-field-unlimited-1-value']);
-    $this->assertTrue($error_field, 'Entity 1: the error was flagged on the correct element.');
+    $this->assertCount(1, $error_field, 'Entity 1: the error was flagged on the correct element.');
     $edit = [
       'entity_2[field_unlimited][1][value]' => -1,
     ];
     $this->drupalPostForm('test-entity/nested/1/2', $edit, t('Save'));
     $this->assertRaw(t('%label does not accept the value -1', ['%label' => 'Unlimited field']), 'Entity 2: the field validation error was reported.');
     $error_field = $this->xpath('//input[@id=:id and contains(@class, "error")]', [':id' => 'edit-entity-2-field-unlimited-1-value']);
-    $this->assertTrue($error_field, 'Entity 2: the error was flagged on the correct element.');
+    $this->assertCount(1, $error_field, 'Entity 2: the error was flagged on the correct element.');
 
     // Test that reordering works on both entities.
     $edit = [
diff --git a/core/modules/field/tests/src/Kernel/BulkDeleteTest.php b/core/modules/field/tests/src/Kernel/BulkDeleteTest.php
index fb0e87d0f00..f9fba84ed56 100644
--- a/core/modules/field/tests/src/Kernel/BulkDeleteTest.php
+++ b/core/modules/field/tests/src/Kernel/BulkDeleteTest.php
@@ -200,7 +200,7 @@ class BulkDeleteTest extends FieldKernelTestBase {
       ->condition('type', $bundle)
       ->condition("$field_name.deleted", 0)
       ->execute();
-    $this->assertFalse($found, 'No entities found after deleting');
+    $this->assertEmpty($found, 'No entities found after deleting');
 
     // There are 10 entities of this bundle when deleted fields are allowed, and
     // their values are correct.
@@ -210,8 +210,8 @@ class BulkDeleteTest extends FieldKernelTestBase {
       ->condition("$field_name.deleted", 1)
       ->sort('id')
       ->execute();
-    $this->assertEqual(count($found), 10, 'Correct number of entities found after deleting');
-    $this->assertFalse(array_diff($found, array_keys($this->entities)));
+    $this->assertCount(10, $found, 'Correct number of entities found after deleting');
+    $this->assertEmpty(array_diff($found, array_keys($this->entities)));
   }
 
   /**
diff --git a/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php b/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php
index 20f69910500..a97cf3668c3 100644
--- a/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php
@@ -278,9 +278,9 @@ class FieldAttachStorageTest extends FieldKernelTestBase {
     $controller->resetCache();
     foreach ([0, 1, 2] as $vid) {
       $revision = $controller->loadRevision($vid);
-      $this->assertFalse($revision);
+      $this->assertNull($revision);
     }
-    $this->assertFalse($controller->load($entity->id()));
+    $this->assertNull($controller->load($entity->id()));
   }
 
   /**
@@ -370,8 +370,8 @@ class FieldAttachStorageTest extends FieldKernelTestBase {
     $this->assertTrue(empty($entity->{$field_name}), 'No data for second field');
 
     // Verify that the fields are gone.
-    $this->assertFalse(FieldConfig::load('entity_test.' . $this->fieldTestData->field->getTargetBundle() . '.' . $this->fieldTestData->field_name), "First field is deleted");
-    $this->assertFalse(FieldConfig::load('entity_test.' . $field['bundle'] . '.' . $field_name), "Second field is deleted");
+    $this->assertNull(FieldConfig::load('entity_test.' . $this->fieldTestData->field->getTargetBundle() . '.' . $this->fieldTestData->field_name), "First field is deleted");
+    $this->assertNull(FieldConfig::load('entity_test.' . $field['bundle'] . '.' . $field_name), "Second field is deleted");
   }
 
 }
diff --git a/core/modules/field/tests/src/Kernel/FieldCrudTest.php b/core/modules/field/tests/src/Kernel/FieldCrudTest.php
index ad8e7c72e9f..c6230046ac9 100644
--- a/core/modules/field/tests/src/Kernel/FieldCrudTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldCrudTest.php
@@ -69,7 +69,7 @@ class FieldCrudTest extends FieldKernelTestBase {
     $field->save();
 
     $field = FieldConfig::load($field->id());
-    $this->assertTrue($field->getSetting('field_setting_from_config_data'));
+    $this->assertEquals('TRUE', $field->getSetting('field_setting_from_config_data'));
     $this->assertNull($field->getSetting('config_data_from_field_setting'));
 
     // Read the configuration. Check against raw configuration data rather than
@@ -314,8 +314,8 @@ class FieldCrudTest extends FieldKernelTestBase {
     FieldConfig::create($this->fieldDefinition)->save();
     FieldConfig::create($field_definition_2)->save();
     $field_storage->delete();
-    $this->assertFalse(FieldConfig::loadByName('entity_test', $this->fieldDefinition['bundle'], $field_storage->getName()));
-    $this->assertFalse(FieldConfig::loadByName('entity_test', $field_definition_2['bundle'], $field_storage->getName()));
+    $this->assertNull(FieldConfig::loadByName('entity_test', $this->fieldDefinition['bundle'], $field_storage->getName()));
+    $this->assertNull(FieldConfig::loadByName('entity_test', $field_definition_2['bundle'], $field_storage->getName()));
 
     // Check that deletion of the last field deletes the storage.
     $field_storage = FieldStorageConfig::create($this->fieldStorageDefinition);
@@ -325,9 +325,9 @@ class FieldCrudTest extends FieldKernelTestBase {
     $field_2 = FieldConfig::create($field_definition_2);
     $field_2->save();
     $field->delete();
-    $this->assertTrue(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
+    $this->assertNotEmpty(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
     $field_2->delete();
-    $this->assertFalse(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
+    $this->assertNull(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
 
     // Check that deletion of all fields using a storage simultaneously deletes
     // the storage.
@@ -338,7 +338,7 @@ class FieldCrudTest extends FieldKernelTestBase {
     $field_2 = FieldConfig::create($field_definition_2);
     $field_2->save();
     $this->container->get('entity_type.manager')->getStorage('field_config')->delete([$field, $field_2]);
-    $this->assertFalse(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
+    $this->assertNull(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
   }
 
 }
diff --git a/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php b/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php
index e889905ba84..af12c239672 100644
--- a/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php
@@ -26,11 +26,11 @@ class FieldImportCreateTest extends FieldKernelTestBase {
     $field_id_2b = "entity_test.test_bundle.$field_name_2";
 
     // Check that the field storages and fields do not exist yet.
-    $this->assertFalse(FieldStorageConfig::load($field_storage_id));
-    $this->assertFalse(FieldConfig::load($field_id));
-    $this->assertFalse(FieldStorageConfig::load($field_storage_id_2));
-    $this->assertFalse(FieldConfig::load($field_id_2a));
-    $this->assertFalse(FieldConfig::load($field_id_2b));
+    $this->assertNull(FieldStorageConfig::load($field_storage_id));
+    $this->assertNull(FieldConfig::load($field_id));
+    $this->assertNull(FieldStorageConfig::load($field_storage_id_2));
+    $this->assertNull(FieldConfig::load($field_id_2a));
+    $this->assertNull(FieldConfig::load($field_id_2b));
 
     // Create a second bundle for the 'Entity test' entity type.
     entity_test_create_bundle('test_bundle');
@@ -41,15 +41,17 @@ class FieldImportCreateTest extends FieldKernelTestBase {
 
     // A field storage with one single field.
     $field_storage = FieldStorageConfig::load($field_storage_id);
-    $this->assertTrue($field_storage, 'The field was created.');
+    $this->assertNotEmpty($field_storage, 'The field was created.');
     $field = FieldConfig::load($field_id);
-    $this->assertTrue($field, 'The field was deleted.');
+    $this->assertNotEmpty($field, 'The field was deleted.');
 
     // A field storage with two fields.
     $field_storage_2 = FieldStorageConfig::load($field_storage_id_2);
-    $this->assertTrue($field_storage_2, 'The second field was created.');
-    $this->assertTrue($field->getTargetBundle(), 'test_bundle', 'The second field was created on bundle test_bundle.');
-    $this->assertTrue($field->getTargetBundle(), 'test_bundle_2', 'The second field was created on bundle test_bundle_2.');
+    $this->assertNotEmpty($field_storage_2, 'The second field was created.');
+    $field2a = FieldConfig::load($field_id_2a);
+    $this->assertEquals('entity_test', $field2a->getTargetBundle(), 'The second field was created on bundle entity_test.');
+    $field2b = FieldConfig::load($field_id_2b);
+    $this->assertEquals('test_bundle', $field2b->getTargetBundle(), 'The second field was created on bundle test_bundle.');
 
     // Tests fields.
     $ids = \Drupal::entityQuery('field_config')
@@ -96,26 +98,26 @@ class FieldImportCreateTest extends FieldKernelTestBase {
     $target_dir = Settings::get('config_sync_directory');
     /** @var \Drupal\Core\File\FileSystemInterface $file_system */
     $file_system = \Drupal::service('file_system');
-    $this->assertTrue($file_system->copy("$src_dir/$field_storage_config_name.yml", "$target_dir/$field_storage_config_name.yml"));
-    $this->assertTrue($file_system->copy("$src_dir/$field_config_name.yml", "$target_dir/$field_config_name.yml"));
-    $this->assertTrue($file_system->copy("$src_dir/$field_storage_config_name_2.yml", "$target_dir/$field_storage_config_name_2.yml"));
-    $this->assertTrue($file_system->copy("$src_dir/$field_config_name_2a.yml", "$target_dir/$field_config_name_2a.yml"));
-    $this->assertTrue($file_system->copy("$src_dir/$field_config_name_2b.yml", "$target_dir/$field_config_name_2b.yml"));
+    $this->assertNotFalse($file_system->copy("$src_dir/$field_storage_config_name.yml", "$target_dir/$field_storage_config_name.yml"));
+    $this->assertNotFalse($file_system->copy("$src_dir/$field_config_name.yml", "$target_dir/$field_config_name.yml"));
+    $this->assertNotFalse($file_system->copy("$src_dir/$field_storage_config_name_2.yml", "$target_dir/$field_storage_config_name_2.yml"));
+    $this->assertNotFalse($file_system->copy("$src_dir/$field_config_name_2a.yml", "$target_dir/$field_config_name_2a.yml"));
+    $this->assertNotFalse($file_system->copy("$src_dir/$field_config_name_2b.yml", "$target_dir/$field_config_name_2b.yml"));
 
     // Import the content of the sync directory.
     $this->configImporter()->import();
 
     // Check that the field and storage were created.
     $field_storage = FieldStorageConfig::load($field_storage_id);
-    $this->assertTrue($field_storage, 'Test import storage field from sync exists');
+    $this->assertNotEmpty($field_storage, 'Test import storage field from sync exists');
     $field = FieldConfig::load($field_id);
-    $this->assertTrue($field, 'Test import field  from sync exists');
+    $this->assertNotEmpty($field, 'Test import field  from sync exists');
     $field_storage = FieldStorageConfig::load($field_storage_id_2);
-    $this->assertTrue($field_storage, 'Test import storage field 2 from sync exists');
+    $this->assertNotEmpty($field_storage, 'Test import storage field 2 from sync exists');
     $field = FieldConfig::load($field_id_2a);
-    $this->assertTrue($field, 'Test import field 2a from sync exists');
+    $this->assertNotEmpty($field, 'Test import field 2a from sync exists');
     $field = FieldConfig::load($field_id_2b);
-    $this->assertTrue($field, 'Test import field 2b from sync exists');
+    $this->assertNotEmpty($field, 'Test import field 2b from sync exists');
   }
 
 }
diff --git a/core/modules/field/tests/src/Kernel/FieldImportDeleteTest.php b/core/modules/field/tests/src/Kernel/FieldImportDeleteTest.php
index cfede1e3861..ddf31f64d36 100644
--- a/core/modules/field/tests/src/Kernel/FieldImportDeleteTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldImportDeleteTest.php
@@ -84,19 +84,19 @@ class FieldImportDeleteTest extends FieldKernelTestBase {
     // Check that the field storages and fields are gone.
     \Drupal::entityTypeManager()->getStorage('field_storage_config')->resetCache([$field_storage_id]);
     $field_storage = FieldStorageConfig::load($field_storage_id);
-    $this->assertFalse($field_storage, 'The field storage was deleted.');
+    $this->assertNull($field_storage, 'The field storage was deleted.');
     \Drupal::entityTypeManager()->getStorage('field_storage_config')->resetCache([$field_storage_id_2]);
     $field_storage_2 = FieldStorageConfig::load($field_storage_id_2);
-    $this->assertFalse($field_storage_2, 'The second field storage was deleted.');
+    $this->assertNull($field_storage_2, 'The second field storage was deleted.');
     \Drupal::entityTypeManager()->getStorage('field_config')->resetCache([$field_id]);
     $field = FieldConfig::load($field_id);
-    $this->assertFalse($field, 'The field was deleted.');
+    $this->assertNull($field, 'The field was deleted.');
     \Drupal::entityTypeManager()->getStorage('field_config')->resetCache([$field_id_2a]);
     $field_2a = FieldConfig::load($field_id_2a);
-    $this->assertFalse($field_2a, 'The second field on test bundle was deleted.');
+    $this->assertNull($field_2a, 'The second field on test bundle was deleted.');
     \Drupal::entityTypeManager()->getStorage('field_config')->resetCache([$field_id_2b]);
     $field_2b = FieldConfig::load($field_id_2b);
-    $this->assertFalse($field_2b, 'The second field on test bundle 2 was deleted.');
+    $this->assertNull($field_2b, 'The second field on test bundle 2 was deleted.');
 
     // Check that all config files are gone.
     $active = $this->container->get('config.storage');
diff --git a/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php b/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php
index 065ba2743a1..e2b1bf327e6 100644
--- a/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php
@@ -100,7 +100,7 @@ class FieldImportDeleteUninstallTest extends FieldKernelTestBase {
     $this->configImporter()->import();
 
     $this->assertFalse(\Drupal::moduleHandler()->moduleExists('telephone'));
-    $this->assertFalse(\Drupal::service('entity.repository')->loadEntityByUuid('field_storage_config', $field_storage->uuid()), 'The test field has been deleted by the configuration synchronization');
+    $this->assertNull(\Drupal::service('entity.repository')->loadEntityByUuid('field_storage_config', $field_storage->uuid()), 'The test field has been deleted by the configuration synchronization');
     $deleted_storages = \Drupal::state()->get('field.storage.deleted') ?: [];
     $this->assertFalse(isset($deleted_storages[$field_storage->uuid()]), 'Telephone field has been completed removed from the system.');
     $this->assertTrue(isset($deleted_storages[$unrelated_field_storage->uuid()]), 'Unrelated field not purged by configuration synchronization.');
diff --git a/core/modules/field/tests/src/Kernel/FieldStorageCrudTest.php b/core/modules/field/tests/src/Kernel/FieldStorageCrudTest.php
index 82eae161d01..98cc95581d1 100644
--- a/core/modules/field/tests/src/Kernel/FieldStorageCrudTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldStorageCrudTest.php
@@ -42,7 +42,7 @@ class FieldStorageCrudTest extends FieldKernelTestBase {
     $field_storage->save();
 
     $field_storage = FieldStorageConfig::load($field_storage->id());
-    $this->assertTrue($field_storage->getSetting('storage_setting_from_config_data'));
+    $this->assertEquals('TRUE', $field_storage->getSetting('storage_setting_from_config_data'));
     $this->assertNull($field_storage->getSetting('config_data_from_storage_setting'));
 
     $mem = field_test_memorize();
diff --git a/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldWidgetSettingsTest.php b/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldWidgetSettingsTest.php
index 75748a35ea2..284f69dd0d3 100644
--- a/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldWidgetSettingsTest.php
+++ b/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldWidgetSettingsTest.php
@@ -64,7 +64,7 @@ class MigrateFieldWidgetSettingsTest extends MigrateDrupal6TestBase {
     $component = $form_display->getComponent('field_test_link');
     $this->assertIdentical('link_default', $component['type']);
     $this->assertIdentical(7, $component['weight']);
-    $this->assertFalse(array_filter($component['settings']));
+    $this->assertEmpty(array_filter($component['settings']));
 
     // File field.
     $component = $form_display->getComponent('field_test_filefield');
diff --git a/core/modules/field/tests/src/Kernel/String/UuidFormatterTest.php b/core/modules/field/tests/src/Kernel/String/UuidFormatterTest.php
index a942eab7637..0bcf2469fe7 100644
--- a/core/modules/field/tests/src/Kernel/String/UuidFormatterTest.php
+++ b/core/modules/field/tests/src/Kernel/String/UuidFormatterTest.php
@@ -43,7 +43,7 @@ class UuidFormatterTest extends KernelTestBase {
     // Verify default render.
     $render_array = $uuid_field->view([]);
     $this->assertIdentical($render_array[0]['#context']['value'], $entity->uuid(), 'The rendered UUID matches the entity UUID.');
-    $this->assertTrue(strpos($this->render($render_array), $entity->uuid()), 'The rendered UUID found.');
+    $this->assertContains($entity->uuid(), $this->render($render_array), 'The rendered UUID found.');
 
     // Verify customized render.
     $render_array = $uuid_field->view(['settings' => ['link_to_entity' => TRUE]]);
@@ -51,8 +51,8 @@ class UuidFormatterTest extends KernelTestBase {
     $this->assertIdentical($render_array[0]['#title']['#context']['value'], $entity->uuid());
     $this->assertIdentical($render_array[0]['#url']->toString(), $entity->toUrl()->toString());
     $rendered = $this->render($render_array);
-    $this->assertTrue(strpos($rendered, $entity->uuid()), 'The rendered UUID found.');
-    $this->assertTrue(strpos($rendered, $entity->toUrl()->toString()), 'The rendered entity URL found.');
+    $this->assertContains($entity->uuid(), $rendered, 'The rendered UUID found.');
+    $this->assertContains($entity->toUrl()->toString(), $rendered, 'The rendered entity URL found.');
   }
 
 }
diff --git a/core/modules/field/tests/src/Kernel/Views/HandlerFieldFieldTest.php b/core/modules/field/tests/src/Kernel/Views/HandlerFieldFieldTest.php
index ce8fed051f5..0cdc94f7595 100644
--- a/core/modules/field/tests/src/Kernel/Views/HandlerFieldFieldTest.php
+++ b/core/modules/field/tests/src/Kernel/Views/HandlerFieldFieldTest.php
@@ -138,7 +138,7 @@ class HandlerFieldFieldTest extends KernelTestBase {
       $field_name = $this->fieldStorages[6]->getName();
       $rendered_field = $view->style_plugin->getField($i, $field_name);
       // Check that a hidden field is not rendered.
-      $this->assertFalse($rendered_field);
+      $this->assertNull($rendered_field);
     }
   }
 
diff --git a/core/modules/field_ui/tests/src/Functional/ManageFieldsFunctionalTest.php b/core/modules/field_ui/tests/src/Functional/ManageFieldsFunctionalTest.php
index 616bedd1b74..c9dcd3490c7 100644
--- a/core/modules/field_ui/tests/src/Functional/ManageFieldsFunctionalTest.php
+++ b/core/modules/field_ui/tests/src/Functional/ManageFieldsFunctionalTest.php
@@ -231,9 +231,9 @@ class ManageFieldsFunctionalTest extends BrowserTestBase {
 
     // Check that fields of other entity types (here, the 'comment_body' field)
     // do not show up in the "Re-use existing field" list.
-    $this->assertFalse($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value="comment"]'), 'The list of options respects entity type restrictions.');
+    $this->assertEmpty($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value="comment"]'), 'The list of options respects entity type restrictions.');
     // Validate the FALSE assertion above by also testing a valid one.
-    $this->assertTrue($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value=:field_name]', [':field_name' => $this->fieldName]), 'The list of options shows a valid option.');
+    $this->assertNotEmpty($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value=:field_name]', [':field_name' => $this->fieldName]), 'The list of options shows a valid option.');
 
     // Add a new field based on an existing field.
     $this->fieldUIAddExistingField("admin/structure/types/manage/page", $this->fieldName, $this->fieldLabel . '_2');
@@ -587,8 +587,8 @@ class ManageFieldsFunctionalTest extends BrowserTestBase {
   public function testHiddenFields() {
     // Check that the field type is not available in the 'add new field' row.
     $this->drupalGet('admin/structure/types/manage/' . $this->contentType . '/fields/add-field');
-    $this->assertFalse($this->xpath('//select[@id="edit-new-storage-type"]//option[@value="hidden_test_field"]'), "The 'add new field' select respects field types 'no_ui' property.");
-    $this->assertTrue($this->xpath('//select[@id="edit-new-storage-type"]//option[@value="shape"]'), "The 'add new field' select shows a valid option.");
+    $this->assertEmpty($this->xpath('//select[@id="edit-new-storage-type"]//option[@value="hidden_test_field"]'), "The 'add new field' select respects field types 'no_ui' property.");
+    $this->assertNotEmpty($this->xpath('//select[@id="edit-new-storage-type"]//option[@value="shape"]'), "The 'add new field' select shows a valid option.");
 
     // Create a field storage and a field programmatically.
     $field_name = 'hidden_test_field';
@@ -608,7 +608,7 @@ class ManageFieldsFunctionalTest extends BrowserTestBase {
       ->getFormDisplay('node', $this->contentType)
       ->setComponent($field_name)
       ->save();
-    $this->assertTrue(FieldConfig::load('node.' . $this->contentType . '.' . $field_name), new FormattableMarkup('A field of the field storage %field was created programmatically.', ['%field' => $field_name]));
+    $this->assertInstanceOf(FieldConfig::class, FieldConfig::load('node.' . $this->contentType . '.' . $field_name), new FormattableMarkup('A field of the field storage %field was created programmatically.', ['%field' => $field_name]));
 
     // Check that the newly added field appears on the 'Manage Fields'
     // screen.
@@ -618,17 +618,17 @@ class ManageFieldsFunctionalTest extends BrowserTestBase {
     // Check that the field does not appear in the 're-use existing field' row
     // on other bundles.
     $this->drupalGet('admin/structure/types/manage/page/fields/add-field');
-    $this->assertFalse($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value=:field_name]', [':field_name' => $field_name]), "The 're-use existing field' select respects field types 'no_ui' property.");
-    $this->assertTrue($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value=:field_name]', [':field_name' => 'field_tags']), "The 're-use existing field' select shows a valid option.");
+    $this->assertEmpty($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value=:field_name]', [':field_name' => $field_name]), "The 're-use existing field' select respects field types 'no_ui' property.");
+    $this->assertNotEmpty($this->xpath('//select[@id="edit-existing-storage-name"]//option[@value=:field_name]', [':field_name' => 'field_tags']), "The 're-use existing field' select shows a valid option.");
 
     // Check that non-configurable fields are not available.
     $field_types = \Drupal::service('plugin.manager.field.field_type')->getDefinitions();
     foreach ($field_types as $field_type => $definition) {
       if (empty($definition['no_ui'])) {
-        $this->assertTrue($this->xpath('//select[@id="edit-new-storage-type"]//option[@value=:field_type]', [':field_type' => $field_type]), new FormattableMarkup('Configurable field type @field_type is available.', ['@field_type' => $field_type]));
+        $this->assertNotEmpty($this->xpath('//select[@id="edit-new-storage-type"]//option[@value=:field_type]', [':field_type' => $field_type]), new FormattableMarkup('Configurable field type @field_type is available.', ['@field_type' => $field_type]));
       }
       else {
-        $this->assertFalse($this->xpath('//select[@id="edit-new-storage-type"]//option[@value=:field_type]', [':field_type' => $field_type]), new FormattableMarkup('Non-configurable field type @field_type is not available.', ['@field_type' => $field_type]));
+        $this->assertEmpty($this->xpath('//select[@id="edit-new-storage-type"]//option[@value=:field_type]', [':field_type' => $field_type]), new FormattableMarkup('Non-configurable field type @field_type is not available.', ['@field_type' => $field_type]));
       }
     }
   }
diff --git a/core/modules/field_ui/tests/src/Kernel/EntityDisplayTest.php b/core/modules/field_ui/tests/src/Kernel/EntityDisplayTest.php
index 14775294074..2e6963e0a5c 100644
--- a/core/modules/field_ui/tests/src/Kernel/EntityDisplayTest.php
+++ b/core/modules/field_ui/tests/src/Kernel/EntityDisplayTest.php
@@ -399,18 +399,18 @@ class EntityDisplayTest extends KernelTestBase {
 
     // Check the component exists.
     $display = $display_repository->getViewDisplay('entity_test', 'entity_test');
-    $this->assertTrue($display->getComponent($field_name));
+    $this->assertNotEmpty($display->getComponent($field_name));
     $display = $display_repository->getViewDisplay('entity_test', 'entity_test', 'teaser');
-    $this->assertTrue($display->getComponent($field_name));
+    $this->assertNotEmpty($display->getComponent($field_name));
 
     // Delete the field.
     $field->delete();
 
     // Check that the component has been removed from the entity displays.
     $display = $display_repository->getViewDisplay('entity_test', 'entity_test');
-    $this->assertFalse($display->getComponent($field_name));
+    $this->assertNull($display->getComponent($field_name));
     $display = $display_repository->getViewDisplay('entity_test', 'entity_test', 'teaser');
-    $this->assertFalse($display->getComponent($field_name));
+    $this->assertNull($display->getComponent($field_name));
   }
 
   /**
@@ -455,7 +455,7 @@ class EntityDisplayTest extends KernelTestBase {
     // Removing the text module should remove the field from the view display.
     \Drupal::service('config.manager')->uninstall('module', 'text');
     $display = $display_repository->getViewDisplay('entity_test', 'entity_test');
-    $this->assertFalse($display->getComponent($field_name));
+    $this->assertNull($display->getComponent($field_name));
   }
 
   /**
diff --git a/core/modules/field_ui/tests/src/Kernel/EntityFormDisplayTest.php b/core/modules/field_ui/tests/src/Kernel/EntityFormDisplayTest.php
index 8807e7126cc..0d14cac2b41 100644
--- a/core/modules/field_ui/tests/src/Kernel/EntityFormDisplayTest.php
+++ b/core/modules/field_ui/tests/src/Kernel/EntityFormDisplayTest.php
@@ -217,18 +217,18 @@ class EntityFormDisplayTest extends KernelTestBase {
 
     // Check the component exists.
     $display = $display_repository->getFormDisplay('entity_test', 'entity_test');
-    $this->assertTrue($display->getComponent($field_name));
+    $this->assertNotEmpty($display->getComponent($field_name));
     $display = $display_repository->getFormDisplay('entity_test', 'entity_test', 'compact');
-    $this->assertTrue($display->getComponent($field_name));
+    $this->assertNotEmpty($display->getComponent($field_name));
 
     // Delete the field.
     $field->delete();
 
     // Check that the component has been removed from the entity displays.
     $display = $display_repository->getFormDisplay('entity_test', 'entity_test');
-    $this->assertFalse($display->getComponent($field_name));
+    $this->assertNull($display->getComponent($field_name));
     $display = $display_repository->getFormDisplay('entity_test', 'entity_test', 'compact');
-    $this->assertFalse($display->getComponent($field_name));
+    $this->assertNull($display->getComponent($field_name));
   }
 
   /**
@@ -273,7 +273,7 @@ class EntityFormDisplayTest extends KernelTestBase {
     // Removing the text module should remove the field from the form display.
     \Drupal::service('config.manager')->uninstall('module', 'text');
     $display = $display_repository->getFormDisplay('entity_test', 'entity_test');
-    $this->assertFalse($display->getComponent($field_name));
+    $this->assertNull($display->getComponent($field_name));
   }
 
 }
diff --git a/core/modules/file/tests/src/Functional/DownloadTest.php b/core/modules/file/tests/src/Functional/DownloadTest.php
index 133729f4b56..5658cc7380e 100644
--- a/core/modules/file/tests/src/Functional/DownloadTest.php
+++ b/core/modules/file/tests/src/Functional/DownloadTest.php
@@ -75,7 +75,7 @@ class DownloadTest extends FileManagedTestBase {
     file_test_set_return('download', ['x-foo' => 'Bar']);
     $this->drupalGet($url);
     $this->assertEqual($this->drupalGetHeader('x-foo'), 'Bar', 'Found header set by file_test module on private download.');
-    $this->assertFalse($this->drupalGetHeader('x-drupal-cache'), 'Page cache is disabled on private file download.');
+    $this->assertNull($this->drupalGetHeader('x-drupal-cache'), 'Page cache is disabled on private file download.');
     $this->assertResponse(200, 'Correctly allowed access to a file when file_test provides headers.');
 
     // Test that the file transferred correctly.
diff --git a/core/modules/file/tests/src/Functional/FileFieldPathTest.php b/core/modules/file/tests/src/Functional/FileFieldPathTest.php
index 0a0fa79a573..f89e9982b8b 100644
--- a/core/modules/file/tests/src/Functional/FileFieldPathTest.php
+++ b/core/modules/file/tests/src/Functional/FileFieldPathTest.php
@@ -93,7 +93,7 @@ class FileFieldPathTest extends FileFieldTestBase {
     $base_path = substr($expected_path, 0, $pos);
     $extension = substr($expected_path, $pos + 1);
 
-    $result = preg_match('/' . preg_quote($base_path, '/') . '(_[0-9]+)?\.' . preg_quote($extension, '/') . '/', $actual_path);
+    $result = (bool) preg_match('/' . preg_quote($base_path, '/') . '(_[0-9]+)?\.' . preg_quote($extension, '/') . '/', $actual_path);
     $this->assertTrue($result, $message);
   }
 
diff --git a/core/modules/file/tests/src/Functional/FileFieldTestBase.php b/core/modules/file/tests/src/Functional/FileFieldTestBase.php
index fc57f1747fd..05f084ee347 100644
--- a/core/modules/file/tests/src/Functional/FileFieldTestBase.php
+++ b/core/modules/file/tests/src/Functional/FileFieldTestBase.php
@@ -225,7 +225,7 @@ abstract class FileFieldTestBase extends BrowserTestBase {
   public function assertFileEntryNotExists($file, $message) {
     $this->container->get('entity_type.manager')->getStorage('file')->resetCache();
     $message = isset($message) ? $message : new FormattableMarkup('File %file exists in database at the correct path.', ['%file' => $file->getFileUri()]);
-    $this->assertFalse(File::load($file->id()), $message);
+    $this->assertNull(File::load($file->id()), $message);
   }
 
   /**
diff --git a/core/modules/file/tests/src/Functional/FileListingTest.php b/core/modules/file/tests/src/Functional/FileListingTest.php
index 4feffa5d01f..a263462e114 100644
--- a/core/modules/file/tests/src/Functional/FileListingTest.php
+++ b/core/modules/file/tests/src/Functional/FileListingTest.php
@@ -115,7 +115,8 @@ class FileListingTest extends FileFieldTestBase {
       $this->assertLinkByHref(file_create_url($file->getFileUri()));
       $this->assertLinkByHref('admin/content/files/usage/' . $file->id());
     }
-    $this->assertFalse(preg_match('/views-field-status priority-low\">\s*' . t('Temporary') . '/', $this->getSession()->getPage()->getContent()), 'All files are stored as permanent.');
+    $this->assertSession()->elementTextNotContains('css', 'table.views-table', 'Temporary');
+    $this->assertSession()->elementTextContains('css', 'table.views-table', 'Permanent');
 
     // Use one file two times and check usage information.
     $orphaned_file = $nodes[1]->file->target_id;
diff --git a/core/modules/file/tests/src/Functional/FilePrivateTest.php b/core/modules/file/tests/src/Functional/FilePrivateTest.php
index 1ac6d138ea8..ad282e8a637 100644
--- a/core/modules/file/tests/src/Functional/FilePrivateTest.php
+++ b/core/modules/file/tests/src/Functional/FilePrivateTest.php
@@ -150,7 +150,7 @@ class FilePrivateTest extends FileFieldTestBase {
     $file = end($files);
     $this->assertTrue($file->isTemporary(), 'File is temporary.');
     $usage = $this->container->get('file.usage')->listUsage($file);
-    $this->assertFalse($usage, 'No file usage found.');
+    $this->assertEmpty($usage, 'No file usage found.');
     $file_url = file_create_url($file->getFileUri());
     $this->drupalGet($file_url);
     $this->assertResponse(200, 'Confirmed that the anonymous uploader has access to the temporary file.');
@@ -178,7 +178,7 @@ class FilePrivateTest extends FileFieldTestBase {
     $file = File::load($file_id);
     $this->assertTrue($file->isTemporary(), 'File is temporary.');
     $usage = $this->container->get('file.usage')->listUsage($file);
-    $this->assertFalse($usage, 'No file usage found.');
+    $this->assertEmpty($usage, 'No file usage found.');
     $file_url = file_create_url($file->getFileUri());
     $this->drupalGet($file_url);
     $this->assertResponse(200, 'Confirmed that the anonymous uploader has access to the file whose references were removed.');
@@ -199,7 +199,7 @@ class FilePrivateTest extends FileFieldTestBase {
     $file = File::load($new_node->{$field_name}->target_id);
     $this->assertTrue($file->isPermanent(), 'File is permanent.');
     $usage = $this->container->get('file.usage')->listUsage($file);
-    $this->assertTrue($usage, 'File usage found.');
+    $this->assertCount(1, $usage, 'File usage found.');
     $file_url = file_create_url($file->getFileUri());
     $this->drupalGet($file_url);
     $this->assertResponse(200, 'Confirmed that the anonymous uploader has access to the permanent file that is referenced by a published node.');
@@ -224,7 +224,7 @@ class FilePrivateTest extends FileFieldTestBase {
     $file = File::load($new_node->{$field_name}->target_id);
     $this->assertTrue($file->isPermanent(), 'File is permanent.');
     $usage = $this->container->get('file.usage')->listUsage($file);
-    $this->assertTrue($usage, 'File usage found.');
+    $this->assertCount(1, $usage, 'File usage found.');
     $file_url = file_create_url($file->getFileUri());
     $this->drupalGet($file_url);
     $this->assertResponse(403, 'Confirmed that the anonymous uploader cannot access the permanent file when it is referenced by an unpublished node.');
diff --git a/core/modules/file/tests/src/Functional/SaveUploadFormTest.php b/core/modules/file/tests/src/Functional/SaveUploadFormTest.php
index b4d7676d198..7dccfeb3184 100644
--- a/core/modules/file/tests/src/Functional/SaveUploadFormTest.php
+++ b/core/modules/file/tests/src/Functional/SaveUploadFormTest.php
@@ -102,7 +102,7 @@ class SaveUploadFormTest extends FileManagedTestBase {
     $max_fid_after = (int) \Drupal::entityQueryAggregate('file')->aggregate('fid', 'max')->execute()[0]['fid_max'];
     $this->assertTrue($max_fid_after > $this->maxFidBefore, 'A new file was created.');
     $file1 = File::load($max_fid_after);
-    $this->assertTrue($file1, 'Loaded the file.');
+    $this->assertInstanceOf(File::class, $file1, 'Loaded the file.');
     // MIME type of the uploaded image may be either image/jpeg or image/png.
     $this->assertEqual(substr($file1->getMimeType(), 0, 5), 'image', 'A MIME type was set.');
 
@@ -123,7 +123,7 @@ class SaveUploadFormTest extends FileManagedTestBase {
     $this->assertFileHooksCalled(['validate', 'insert']);
 
     $file2 = File::load($max_fid_after);
-    $this->assertTrue($file2, 'Loaded the file');
+    $this->assertInstanceOf(File::class, $file2, 'Loaded the file');
     // MIME type of the uploaded image may be either image/jpeg or image/png.
     $this->assertEqual(substr($file2->getMimeType(), 0, 5), 'image', 'A MIME type was set.');
 
diff --git a/core/modules/file/tests/src/Functional/SaveUploadTest.php b/core/modules/file/tests/src/Functional/SaveUploadTest.php
index 8e5c1f1ae63..446b565dc13 100644
--- a/core/modules/file/tests/src/Functional/SaveUploadTest.php
+++ b/core/modules/file/tests/src/Functional/SaveUploadTest.php
@@ -97,7 +97,7 @@ class SaveUploadTest extends FileManagedTestBase {
     $max_fid_after = (int) \Drupal::entityQueryAggregate('file')->aggregate('fid', 'max')->execute()[0]['fid_max'];
     $this->assertTrue($max_fid_after > $this->maxFidBefore, 'A new file was created.');
     $file1 = File::load($max_fid_after);
-    $this->assertTrue($file1, 'Loaded the file.');
+    $this->assertInstanceOf(File::class, $file1, 'Loaded the file.');
     // MIME type of the uploaded image may be either image/jpeg or image/png.
     $this->assertEqual(substr($file1->getMimeType(), 0, 5), 'image', 'A MIME type was set.');
 
@@ -116,7 +116,7 @@ class SaveUploadTest extends FileManagedTestBase {
     $this->assertFileHooksCalled(['validate', 'insert']);
 
     $file2 = File::load($max_fid_after);
-    $this->assertTrue($file2, 'Loaded the file');
+    $this->assertInstanceOf(File::class, $file2, 'Loaded the file');
     // MIME type of the uploaded image may be either image/jpeg or image/png.
     $this->assertEqual(substr($file2->getMimeType(), 0, 5), 'image', 'A MIME type was set.');
 
diff --git a/core/modules/file/tests/src/Kernel/CopyTest.php b/core/modules/file/tests/src/Kernel/CopyTest.php
index 8fe7b10b841..f5093508edc 100644
--- a/core/modules/file/tests/src/Kernel/CopyTest.php
+++ b/core/modules/file/tests/src/Kernel/CopyTest.php
@@ -25,7 +25,7 @@ class CopyTest extends FileManagedUnitTestBase {
     $result = file_copy(clone $source, $desired_uri, FileSystemInterface::EXISTS_ERROR);
 
     // Check the return status and that the contents changed.
-    $this->assertTrue($result, 'File copied successfully.');
+    $this->assertNotFalse($result, 'File copied successfully.');
     $this->assertEqual($contents, file_get_contents($result->getFileUri()), 'Contents of file were copied correctly.');
 
     // Check that the correct hooks were called.
@@ -56,7 +56,7 @@ class CopyTest extends FileManagedUnitTestBase {
     $result = file_copy(clone $source, $target->getFileUri(), FileSystemInterface::EXISTS_RENAME);
 
     // Check the return status and that the contents changed.
-    $this->assertTrue($result, 'File copied successfully.');
+    $this->assertNotFalse($result, 'File copied successfully.');
     $this->assertEqual($contents, file_get_contents($result->getFileUri()), 'Contents of file were copied correctly.');
     $this->assertNotEqual($result->getFileUri(), $source->getFileUri(), 'Returned file path has changed from the original.');
 
@@ -96,7 +96,7 @@ class CopyTest extends FileManagedUnitTestBase {
     $result = file_copy(clone $source, $target->getFileUri(), FileSystemInterface::EXISTS_REPLACE);
 
     // Check the return status and that the contents changed.
-    $this->assertTrue($result, 'File copied successfully.');
+    $this->assertNotFalse($result, 'File copied successfully.');
     $this->assertEqual($contents, file_get_contents($result->getFileUri()), 'Contents of file were overwritten.');
     $this->assertDifferentFile($source, $result);
 
diff --git a/core/modules/file/tests/src/Kernel/DeleteTest.php b/core/modules/file/tests/src/Kernel/DeleteTest.php
index a0b3822e26d..e8be244534b 100644
--- a/core/modules/file/tests/src/Kernel/DeleteTest.php
+++ b/core/modules/file/tests/src/Kernel/DeleteTest.php
@@ -23,7 +23,7 @@ class DeleteTest extends FileManagedUnitTestBase {
     $file->delete();
     $this->assertFileHooksCalled(['delete']);
     $this->assertFalse(file_exists($file->getFileUri()), 'Test file has actually been deleted.');
-    $this->assertFalse(File::load($file->id()), 'File was removed from the database.');
+    $this->assertNull(File::load($file->id()), 'File was removed from the database.');
   }
 
   /**
@@ -44,7 +44,7 @@ class DeleteTest extends FileManagedUnitTestBase {
     $usage = $file_usage->listUsage($file);
     $this->assertEqual($usage['testing']['test'], [1 => 1], 'Test file is still in use.');
     $this->assertTrue(file_exists($file->getFileUri()), 'File still exists on the disk.');
-    $this->assertTrue(File::load($file->id()), 'File still exists in the database.');
+    $this->assertNotEmpty(File::load($file->id()), 'File still exists in the database.');
 
     // Clear out the call to hook_file_load().
     file_test_reset();
@@ -55,7 +55,7 @@ class DeleteTest extends FileManagedUnitTestBase {
     $this->assertTrue(empty($usage), 'File usage data was removed.');
     $this->assertTrue(file_exists($file->getFileUri()), 'File still exists on the disk.');
     $file = File::load($file->id());
-    $this->assertTrue($file, 'File still exists in the database.');
+    $this->assertNotEmpty($file, 'File still exists in the database.');
     $this->assertTrue($file->isTemporary(), 'File is temporary.');
     file_test_reset();
 
@@ -74,7 +74,7 @@ class DeleteTest extends FileManagedUnitTestBase {
     // file_cron() loads
     $this->assertFileHooksCalled(['delete']);
     $this->assertFalse(file_exists($file->getFileUri()), 'File has been deleted after its last usage was removed.');
-    $this->assertFalse(File::load($file->id()), 'File was removed from the database.');
+    $this->assertNull(File::load($file->id()), 'File was removed from the database.');
   }
 
   /**
@@ -85,7 +85,7 @@ class DeleteTest extends FileManagedUnitTestBase {
     // Delete the file, but leave it in the file_managed table.
     \Drupal::service('file_system')->delete($file->getFileUri());
     $this->assertFalse(file_exists($file->getFileUri()), 'File is deleted from the filesystem.');
-    $this->assertTrue(File::load($file->id()), 'File exist in file_managed table');
+    $this->assertInstanceOf(File::class, File::load($file->id()), 'File exist in file_managed table');
 
     // Call file_cron() to clean up the file. Make sure the changed timestamp
     // of the file is older than the system.file.temporary_maximum_age
@@ -98,7 +98,7 @@ class DeleteTest extends FileManagedUnitTestBase {
       ->execute();
     \Drupal::service('cron')->run();
 
-    $this->assertFalse(File::load($file->id()), 'File was removed from the database.');
+    $this->assertNull(File::load($file->id()), 'File was removed from the database.');
   }
 
 }
diff --git a/core/modules/file/tests/src/Kernel/LoadTest.php b/core/modules/file/tests/src/Kernel/LoadTest.php
index 45539cf1aeb..56212b4bf0e 100644
--- a/core/modules/file/tests/src/Kernel/LoadTest.php
+++ b/core/modules/file/tests/src/Kernel/LoadTest.php
@@ -16,7 +16,7 @@ class LoadTest extends FileManagedUnitTestBase {
    * Try to load a non-existent file by fid.
    */
   public function testLoadMissingFid() {
-    $this->assertFalse(File::load(-1), 'Try to load an invalid fid fails.');
+    $this->assertNull(File::load(-1), 'Try to load an invalid fid fails.');
     $this->assertFileHooksCalled([]);
   }
 
diff --git a/core/modules/file/tests/src/Kernel/MoveTest.php b/core/modules/file/tests/src/Kernel/MoveTest.php
index db3a46c2be2..94ef5a69755 100644
--- a/core/modules/file/tests/src/Kernel/MoveTest.php
+++ b/core/modules/file/tests/src/Kernel/MoveTest.php
@@ -26,7 +26,7 @@ class MoveTest extends FileManagedUnitTestBase {
     $result = file_move(clone $source, $desired_filepath, FileSystemInterface::EXISTS_ERROR);
 
     // Check the return status and that the contents changed.
-    $this->assertTrue($result, 'File moved successfully.');
+    $this->assertNotFalse($result, 'File moved successfully.');
     $this->assertFalse(file_exists($source->getFileUri()));
     $this->assertEqual($contents, file_get_contents($result->getFileUri()), 'Contents of file correctly written.');
 
@@ -39,7 +39,7 @@ class MoveTest extends FileManagedUnitTestBase {
     // Reload the file from the database and check that the changes were
     // actually saved.
     $loaded_file = File::load($result->id());
-    $this->assertTrue($loaded_file, 'File can be loaded from the database.');
+    $this->assertNotEmpty($loaded_file, 'File can be loaded from the database.');
     $this->assertFileUnchanged($result, $loaded_file);
   }
 
@@ -58,7 +58,7 @@ class MoveTest extends FileManagedUnitTestBase {
     $result = file_move(clone $source, $target->getFileUri(), FileSystemInterface::EXISTS_RENAME);
 
     // Check the return status and that the contents changed.
-    $this->assertTrue($result, 'File moved successfully.');
+    $this->assertNotFalse($result, 'File moved successfully.');
     $this->assertFalse(file_exists($source->getFileUri()));
     $this->assertEqual($contents, file_get_contents($result->getFileUri()), 'Contents of file correctly written.');
 
@@ -95,7 +95,7 @@ class MoveTest extends FileManagedUnitTestBase {
     // Look at the results.
     $this->assertEqual($contents, file_get_contents($result->getFileUri()), 'Contents of file were overwritten.');
     $this->assertFalse(file_exists($source->getFileUri()));
-    $this->assertTrue($result, 'File moved successfully.');
+    $this->assertNotEmpty($result, 'File moved successfully.');
 
     // Check that the correct hooks were called.
     $this->assertFileHooksCalled(['move', 'update', 'delete', 'load']);
diff --git a/core/modules/file/tests/src/Kernel/SaveDataTest.php b/core/modules/file/tests/src/Kernel/SaveDataTest.php
index 346a9f8332e..38a53c601ec 100644
--- a/core/modules/file/tests/src/Kernel/SaveDataTest.php
+++ b/core/modules/file/tests/src/Kernel/SaveDataTest.php
@@ -20,7 +20,7 @@ class SaveDataTest extends FileManagedUnitTestBase {
     $contents = $this->randomMachineName(8);
 
     $result = file_save_data($contents);
-    $this->assertTrue($result, 'Unnamed file saved correctly.');
+    $this->assertNotFalse($result, 'Unnamed file saved correctly.');
 
     $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
     assert($stream_wrapper_manager instanceof StreamWrapperManagerInterface);
@@ -47,7 +47,7 @@ class SaveDataTest extends FileManagedUnitTestBase {
     $filename = 'Текстовый файл.txt';
 
     $result = file_save_data($contents, 'public://' . $filename);
-    $this->assertTrue($result, 'Unnamed file saved correctly.');
+    $this->assertNotFalse($result, 'Unnamed file saved correctly.');
 
     $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
     assert($stream_wrapper_manager instanceof StreamWrapperManagerInterface);
@@ -73,7 +73,7 @@ class SaveDataTest extends FileManagedUnitTestBase {
     $contents = $this->randomMachineName(8);
 
     $result = file_save_data($contents, $existing->getFileUri(), FileSystemInterface::EXISTS_RENAME);
-    $this->assertTrue($result, 'File saved successfully.');
+    $this->assertNotFalse($result, 'File saved successfully.');
 
     $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
     assert($stream_wrapper_manager instanceof StreamWrapperManagerInterface);
@@ -103,7 +103,7 @@ class SaveDataTest extends FileManagedUnitTestBase {
     $contents = $this->randomMachineName(8);
 
     $result = file_save_data($contents, $existing->getFileUri(), FileSystemInterface::EXISTS_REPLACE);
-    $this->assertTrue($result, 'File saved successfully.');
+    $this->assertNotFalse($result, 'File saved successfully.');
 
     $stream_wrapper_manager = \Drupal::service('stream_wrapper_manager');
     assert($stream_wrapper_manager instanceof StreamWrapperManagerInterface);
diff --git a/core/modules/filter/tests/src/Functional/FilterAdminTest.php b/core/modules/filter/tests/src/Functional/FilterAdminTest.php
index ece059a3e81..3f608265ade 100644
--- a/core/modules/filter/tests/src/Functional/FilterAdminTest.php
+++ b/core/modules/filter/tests/src/Functional/FilterAdminTest.php
@@ -299,7 +299,7 @@ class FilterAdminTest extends BrowserTestBase {
     $this->assertNotEmpty($view_link, 'The message area contains a link to a node');
 
     $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertNotEmpty($node, 'Node found in database.');
 
     $this->drupalGet('node/' . $node->id());
     $this->assertRaw($body . $extra_text, 'Filter removed invalid tag.');
diff --git a/core/modules/filter/tests/src/Kernel/FilterDefaultConfigTest.php b/core/modules/filter/tests/src/Kernel/FilterDefaultConfigTest.php
index e16bddade56..49fb44f1170 100644
--- a/core/modules/filter/tests/src/Kernel/FilterDefaultConfigTest.php
+++ b/core/modules/filter/tests/src/Kernel/FilterDefaultConfigTest.php
@@ -39,7 +39,7 @@ class FilterDefaultConfigTest extends KernelTestBase {
     $this->assertEqual($format->get('weight'), 2);
 
     // Verify that format default property values have been added/injected.
-    $this->assertTrue($format->uuid());
+    $this->assertNotEmpty($format->uuid());
 
     // Verify that the loaded format does not contain any roles.
     $this->assertEqual($format->get('roles'), NULL);
diff --git a/core/modules/image/tests/src/Functional/ImageAdminStylesTest.php b/core/modules/image/tests/src/Functional/ImageAdminStylesTest.php
index 989a063fb23..46c96ca2431 100644
--- a/core/modules/image/tests/src/Functional/ImageAdminStylesTest.php
+++ b/core/modules/image/tests/src/Functional/ImageAdminStylesTest.php
@@ -289,7 +289,7 @@ class ImageAdminStylesTest extends ImageFieldTestBase {
     $directory = 'public://styles/' . $style_name;
     $this->assertFalse(is_dir($directory), new FormattableMarkup('Image style %style directory removed on style deletion.', ['%style' => $style->label()]));
 
-    $this->assertFalse(ImageStyle::load($style_name), new FormattableMarkup('Image style %style successfully deleted.', ['%style' => $style->label()]));
+    $this->assertNull(ImageStyle::load($style_name), new FormattableMarkup('Image style %style successfully deleted.', ['%style' => $style->label()]));
 
     // Test empty text when there are no image styles.
 
@@ -499,7 +499,7 @@ class ImageAdminStylesTest extends ImageFieldTestBase {
     $sync->delete('image.style.' . $style_name);
     $this->configImporter()->import();
 
-    $this->assertFalse(ImageStyle::load($style_name), 'Style deleted after config import.');
+    $this->assertNull(ImageStyle::load($style_name), 'Style deleted after config import.');
     $this->assertEqual($this->getImageCount($style), 0, 'Image style was flushed after being deleted by config import.');
   }
 
diff --git a/core/modules/image/tests/src/Functional/ImageFieldDisplayTest.php b/core/modules/image/tests/src/Functional/ImageFieldDisplayTest.php
index c99256c9bcd..96baad54a2e 100644
--- a/core/modules/image/tests/src/Functional/ImageFieldDisplayTest.php
+++ b/core/modules/image/tests/src/Functional/ImageFieldDisplayTest.php
@@ -287,7 +287,7 @@ class ImageFieldDisplayTest extends ImageFieldTestBase {
     $file = $node->{$field_name}->entity;
 
     $url = file_url_transform_relative(ImageStyle::load('medium')->buildUrl($file->getFileUri()));
-    $this->assertTrue($this->cssSelect('img[width=40][height=20][class=image-style-medium][src="' . $url . '"]'));
+    $this->assertSession()->elementExists('css', 'img[width=40][height=20][class=image-style-medium][src="' . $url . '"]');
 
     // Add alt/title fields to the image and verify that they are displayed.
     $image = [
@@ -439,7 +439,7 @@ class ImageFieldDisplayTest extends ImageFieldTestBase {
     \Drupal::service('entity_field.manager')->clearCachedFieldDefinitions();
     $field_storage = FieldStorageConfig::loadByName('node', $field_name);
     $default_image = $field_storage->getSetting('default_image');
-    $this->assertFalse($default_image['uuid'], 'Default image removed from field.');
+    $this->assertEmpty($default_image['uuid'], 'Default image removed from field.');
     // Create an image field that uses the private:// scheme and test that the
     // default image works as expected.
     $private_field_name = strtolower($this->randomMachineName());
diff --git a/core/modules/image/tests/src/Functional/QuickEditImageControllerTest.php b/core/modules/image/tests/src/Functional/QuickEditImageControllerTest.php
index ab95773a596..853a030b897 100644
--- a/core/modules/image/tests/src/Functional/QuickEditImageControllerTest.php
+++ b/core/modules/image/tests/src/Functional/QuickEditImageControllerTest.php
@@ -131,7 +131,7 @@ class QuickEditImageControllerTest extends BrowserTestBase {
         break;
       }
     }
-    $this->assertTrue($valid_image);
+    $this->assertNotFalse($valid_image);
 
     $this->drupalLogin($this->contentAuthorUser);
     $this->uploadImage($valid_image, $node->id(), $this->fieldName, $node->language()->getId());
@@ -160,7 +160,7 @@ class QuickEditImageControllerTest extends BrowserTestBase {
         break;
       }
     }
-    $this->assertTrue($invalid_image);
+    $this->assertNotFalse($invalid_image);
 
     $this->drupalLogin($this->contentAuthorUser);
     $this->uploadImage($invalid_image, $node->id(), $this->fieldName, $node->language()->getId());
diff --git a/core/modules/image/tests/src/FunctionalJavascript/ImageAdminStylesTest.php b/core/modules/image/tests/src/FunctionalJavascript/ImageAdminStylesTest.php
index 67ad74c25de..acc4bdc5b2f 100644
--- a/core/modules/image/tests/src/FunctionalJavascript/ImageAdminStylesTest.php
+++ b/core/modules/image/tests/src/FunctionalJavascript/ImageAdminStylesTest.php
@@ -59,7 +59,7 @@ class ImageAdminStylesTest extends ImageFieldTestBase {
       $this->getSession()->getPage()->pressButton('Ajax refresh');
       $this->assertTrue($page->waitFor(10, function ($page) {
         $ajax_value = $page->find('css', '#ajax-value')->getText();
-        return preg_match('/^Ajax value [0-9.]+ [0-9.]+$/', $ajax_value);
+        return (bool) preg_match('/^Ajax value [0-9.]+ [0-9.]+$/', $ajax_value);
       }));
       $page->pressButton('Update effect');
       $assert->pageTextContains('The image effect was successfully applied.');
diff --git a/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalMultilingualTest.php b/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalMultilingualTest.php
index 4748d68bcc4..1cc79ac7577 100644
--- a/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalMultilingualTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/JsonApiFunctionalMultilingualTest.php
@@ -319,7 +319,7 @@ class JsonApiFunctionalMultilingualTest extends JsonApiFunctionalTestBase {
 
     $response = $this->request('DELETE', Url::fromUri('base:/jsonapi/node/article/' . $this->nodes[0]->uuid()), []);
     $this->assertSame(204, $response->getStatusCode());
-    $this->assertFalse(Node::load($this->nodes[0]->id()));
+    $this->assertNull(Node::load($this->nodes[0]->id()));
   }
 
 }
diff --git a/core/modules/language/tests/src/Functional/LanguageBrowserDetectionAcceptLanguageTest.php b/core/modules/language/tests/src/Functional/LanguageBrowserDetectionAcceptLanguageTest.php
index 849d59f9743..b2ac07895fe 100644
--- a/core/modules/language/tests/src/Functional/LanguageBrowserDetectionAcceptLanguageTest.php
+++ b/core/modules/language/tests/src/Functional/LanguageBrowserDetectionAcceptLanguageTest.php
@@ -79,32 +79,32 @@ class LanguageBrowserDetectionAcceptLanguageTest extends BrowserTestBase {
 
     $this->drupalGet('/system-test/echo/language test', [], ['Accept-Language' => 'en']);
     $this->assertSession()->responseHeaderEquals('Content-Language', 'en');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check with UK browser.
     $this->drupalGet('/system-test/echo/language test', [], ['Accept-Language' => 'en-UK,en']);
     $this->assertSession()->responseHeaderEquals('Content-Language', 'en');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check with french browser.
     $this->drupalGet('/system-test/echo/language test', [], ['Accept-Language' => 'fr-FR,fr']);
     $this->assertSession()->responseHeaderEquals('Content-Language', 'fr');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check with browser without language settings - should return fallback language.
     $this->drupalGet('/system-test/echo/language test', [], ['Accept-Language' => NULL]);
     $this->assertSession()->responseHeaderEquals('Content-Language', 'en');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check with french browser again.
     $this->drupalGet('/system-test/echo/language test', [], ['Accept-Language' => 'fr-FR,fr']);
     $this->assertSession()->responseHeaderEquals('Content-Language', 'fr');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check with UK browser.
     $this->drupalGet('/system-test/echo/language test', [], ['Accept-Language' => 'en-UK,en']);
     $this->assertSession()->responseHeaderEquals('Content-Language', 'en');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check if prefixed URLs are still cached.
     $this->drupalGet('/en/system-test/echo/language test', [], ['Accept-Language' => 'en']);
diff --git a/core/modules/language/tests/src/Functional/LanguageConfigurationElementTest.php b/core/modules/language/tests/src/Functional/LanguageConfigurationElementTest.php
index 5c5640abb48..386f6d93e07 100644
--- a/core/modules/language/tests/src/Functional/LanguageConfigurationElementTest.php
+++ b/core/modules/language/tests/src/Functional/LanguageConfigurationElementTest.php
@@ -209,7 +209,7 @@ class LanguageConfigurationElementTest extends BrowserTestBase {
 
     // Check the language default configuration for articles is present.
     $configuration = \Drupal::entityTypeManager()->getStorage('language_content_settings')->load('node.article');
-    $this->assertTrue($configuration, 'The language configuration is present.');
+    $this->assertNotEmpty($configuration, 'The language configuration is present.');
 
     // Delete 'article' bundle.
     $this->drupalPostForm('admin/structure/types/manage/article/delete', [], t('Delete'));
@@ -217,7 +217,7 @@ class LanguageConfigurationElementTest extends BrowserTestBase {
     // Check that the language configuration has been deleted.
     \Drupal::entityTypeManager()->getStorage('language_content_settings')->resetCache();
     $configuration = \Drupal::entityTypeManager()->getStorage('language_content_settings')->load('node.article');
-    $this->assertFalse($configuration, 'The language configuration was deleted after bundle was deleted.');
+    $this->assertNull($configuration, 'The language configuration was deleted after bundle was deleted.');
   }
 
   /**
diff --git a/core/modules/language/tests/src/Functional/LanguageUILanguageNegotiationTest.php b/core/modules/language/tests/src/Functional/LanguageUILanguageNegotiationTest.php
index ebf6366a577..239a561427b 100644
--- a/core/modules/language/tests/src/Functional/LanguageUILanguageNegotiationTest.php
+++ b/core/modules/language/tests/src/Functional/LanguageUILanguageNegotiationTest.php
@@ -567,7 +567,7 @@ class LanguageUILanguageNegotiationTest extends BrowserTestBase {
 
     // Check if the language switcher block has been created.
     $block = Block::load($block_id);
-    $this->assertTrue($block, 'Language switcher block was created.');
+    $this->assertNotEmpty($block, 'Language switcher block was created.');
 
     // Make sure language_content is not configurable.
     $edit = [
@@ -578,7 +578,7 @@ class LanguageUILanguageNegotiationTest extends BrowserTestBase {
 
     // Check if the language switcher block has been removed.
     $block = Block::load($block_id);
-    $this->assertFalse($block, 'Language switcher block was removed.');
+    $this->assertNull($block, 'Language switcher block was removed.');
   }
 
 }
diff --git a/core/modules/locale/tests/src/Functional/LocaleConfigTranslationTest.php b/core/modules/locale/tests/src/Functional/LocaleConfigTranslationTest.php
index bc1d914c1c6..eeb22ef3d9e 100644
--- a/core/modules/locale/tests/src/Functional/LocaleConfigTranslationTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleConfigTranslationTest.php
@@ -70,7 +70,7 @@ class LocaleConfigTranslationTest extends BrowserTestBase {
     // Check that the maintenance message exists and create translation for it.
     $source = '@site is currently under maintenance. We should be back shortly. Thank you for your patience.';
     $string = $this->storage->findString(['source' => $source, 'context' => '', 'type' => 'configuration']);
-    $this->assertTrue($string, 'Configuration strings have been created upon installation.');
+    $this->assertNotEmpty($string, 'Configuration strings have been created upon installation.');
 
     // Translate using the UI so configuration is refreshed.
     $message = $this->randomMachineName(20);
@@ -95,7 +95,7 @@ class LocaleConfigTranslationTest extends BrowserTestBase {
 
     // Check default medium date format exists and create a translation for it.
     $string = $this->storage->findString(['source' => 'D, m/d/Y - H:i', 'context' => 'PHP date format', 'type' => 'configuration']);
-    $this->assertTrue($string, 'Configuration date formats have been created upon installation.');
+    $this->assertNotEmpty($string, 'Configuration date formats have been created upon installation.');
 
     // Translate using the UI so configuration is refreshed.
     $search = [
@@ -122,14 +122,14 @@ class LocaleConfigTranslationTest extends BrowserTestBase {
 
     // Assert strings from image module config are not available.
     $string = $this->storage->findString(['source' => 'Medium (220×220)', 'context' => '', 'type' => 'configuration']);
-    $this->assertFalse($string, 'Configuration strings have been created upon installation.');
+    $this->assertNull($string, 'Configuration strings have been created upon installation.');
 
     // Enable the image module.
     $this->drupalPostForm('admin/modules', ['modules[image][enable]' => "1"], t('Install'));
     $this->rebuildContainer();
 
     $string = $this->storage->findString(['source' => 'Medium (220×220)', 'context' => '', 'type' => 'configuration']);
-    $this->assertTrue($string, 'Configuration strings have been created upon installation.');
+    $this->assertNotEmpty($string, 'Configuration strings have been created upon installation.');
     $locations = $string->getLocations();
     $this->assertTrue(isset($locations['configuration']) && isset($locations['configuration']['image.style.medium']), 'Configuration string has been created with the right location');
 
@@ -138,7 +138,7 @@ class LocaleConfigTranslationTest extends BrowserTestBase {
     $this->assertEqual(count($translations), 1);
     $translation = reset($translations);
     $this->assertEqual($translation->source, $string->source);
-    $this->assertTrue(empty($translation->translation));
+    $this->assertEmpty($translation->translation);
 
     // Translate using the UI so configuration is refreshed.
     $image_style_label = $this->randomMachineName(20);
@@ -229,22 +229,22 @@ class LocaleConfigTranslationTest extends BrowserTestBase {
     $string = $this->storage->findString(['source' => 'Make content sticky', 'context' => '', 'type' => 'configuration']);
     if ($required) {
       $this->assertFalse($this->config('system.action.node_make_sticky_action')->isNew());
-      $this->assertTrue($string, 'Node action text can be found with node module.');
+      $this->assertNotEmpty($string, 'Node action text can be found with node module.');
     }
     else {
       $this->assertTrue($this->config('system.action.node_make_sticky_action')->isNew());
-      $this->assertFalse($string, 'Node action text can not be found without node module.');
+      $this->assertNull($string, 'Node action text can not be found without node module.');
     }
 
     // Check the optional default configuration in node module.
     $string = $this->storage->findString(['source' => 'No front page content has been created yet.<br/>Follow the <a target="_blank" href="https://www.drupal.org/docs/user_guide/en/index.html">User Guide</a> to start building your site.', 'context' => '', 'type' => 'configuration']);
     if ($optional) {
       $this->assertFalse($this->config('views.view.frontpage')->isNew());
-      $this->assertTrue($string, 'Node view text can be found with node and views modules.');
+      $this->assertNotEmpty($string, 'Node view text can be found with node and views modules.');
     }
     else {
       $this->assertTrue($this->config('views.view.frontpage')->isNew());
-      $this->assertFalse($string, 'Node view text can not be found without node and/or views modules.');
+      $this->assertNull($string, 'Node view text can not be found without node and/or views modules.');
     }
   }
 
diff --git a/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php b/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
index 11906f3893f..9342c6ed842 100644
--- a/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleImportFunctionalTest.php
@@ -317,7 +317,7 @@ class LocaleImportFunctionalTest extends BrowserTestBase {
     $locale_storage = $this->container->get('locale.storage');
     foreach ($config_strings as $config_string) {
       $string = $locale_storage->findString(['source' => $config_string[0], 'context' => '', 'type' => 'configuration']);
-      $this->assertTrue($string, 'Configuration strings have been created upon installation.');
+      $this->assertNotEmpty($string, 'Configuration strings have been created upon installation.');
     }
 
     // Import a .po file to translate.
diff --git a/core/modules/locale/tests/src/Functional/LocaleUpdateBase.php b/core/modules/locale/tests/src/Functional/LocaleUpdateBase.php
index 05221fb997e..2e2d82b6332 100644
--- a/core/modules/locale/tests/src/Functional/LocaleUpdateBase.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateBase.php
@@ -91,7 +91,7 @@ abstract class LocaleUpdateBase extends BrowserTestBase {
     $edit = ['predefined_langcode' => $langcode];
     $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add language'));
     $this->container->get('language_manager')->reset();
-    $this->assertTrue(\Drupal::languageManager()->getLanguage($langcode), new FormattableMarkup('Language %langcode added.', ['%langcode' => $langcode]));
+    $this->assertNotEmpty(\Drupal::languageManager()->getLanguage($langcode), new FormattableMarkup('Language %langcode added.', ['%langcode' => $langcode]));
   }
 
   /**
diff --git a/core/modules/locale/tests/src/Functional/LocaleUpdateInterfaceTest.php b/core/modules/locale/tests/src/Functional/LocaleUpdateInterfaceTest.php
index 5c7d698f424..516d5b6386a 100644
--- a/core/modules/locale/tests/src/Functional/LocaleUpdateInterfaceTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateInterfaceTest.php
@@ -122,7 +122,7 @@ class LocaleUpdateInterfaceTest extends LocaleUpdateBase {
       '@date' => $this->container->get('date.formatter')->format(REQUEST_TIME, 'html_date'),
     ]), 'Core translation update');
     $update_button = $this->xpath('//input[@type="submit"][@value="' . t('Update translations') . '"]');
-    $this->assertTrue($update_button, 'Update translations button');
+    $this->assertNotEmpty($update_button, 'Update translations button');
   }
 
 }
diff --git a/core/modules/locale/tests/src/Functional/LocaleUpdateTest.php b/core/modules/locale/tests/src/Functional/LocaleUpdateTest.php
index 2c25228d10e..d6818a8f143 100644
--- a/core/modules/locale/tests/src/Functional/LocaleUpdateTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleUpdateTest.php
@@ -354,7 +354,7 @@ class LocaleUpdateTest extends LocaleUpdateBase {
     // Check if the language data is added to the database.
     $connection = Database::getConnection();
     $result = $connection->query("SELECT project FROM {locale_file} WHERE langcode='nl'")->fetchField();
-    $this->assertTrue($result, 'Files added to file history');
+    $this->assertNotEmpty($result, 'Files added to file history');
 
     // Remove a language.
     $this->drupalPostForm('admin/config/regional/language/delete/nl', [], t('Delete'));
diff --git a/core/modules/locale/tests/src/Kernel/LocaleStringTest.php b/core/modules/locale/tests/src/Kernel/LocaleStringTest.php
index b0e44000629..885b3c5260f 100644
--- a/core/modules/locale/tests/src/Kernel/LocaleStringTest.php
+++ b/core/modules/locale/tests/src/Kernel/LocaleStringTest.php
@@ -53,7 +53,7 @@ class LocaleStringTest extends KernelTestBase {
   public function testStringCrudApi() {
     // Create source string.
     $source = $this->buildSourceString()->save();
-    $this->assertTrue($source->lid);
+    $this->assertNotEmpty($source->lid);
 
     // Load strings by lid and source.
     $string1 = $this->storage->findString(['lid' => $source->lid]);
@@ -61,7 +61,7 @@ class LocaleStringTest extends KernelTestBase {
     $string2 = $this->storage->findString(['source' => $source->source, 'context' => $source->context]);
     $this->assertEquals($source, $string2);
     $string3 = $this->storage->findString(['source' => $source->source, 'context' => '']);
-    $this->assertFalse($string3);
+    $this->assertNull($string3);
 
     // Check version handling and updating.
     $this->assertEquals('none', $source->version);
@@ -96,9 +96,9 @@ class LocaleStringTest extends KernelTestBase {
 
     $source->delete();
     $string = $this->storage->findString(['lid' => $lid]);
-    $this->assertFalse($string);
+    $this->assertNull($string);
     $deleted = $search = $this->storage->getTranslations(['lid' => $lid]);
-    $this->assertFalse($deleted);
+    $this->assertEmpty($deleted);
 
     // Tests that locations of different types and arbitrary lengths can be
     // added to a source string. Too long locations will be cut off.
diff --git a/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php b/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php
index dacd9e9fe8d..42220d2e138 100644
--- a/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php
+++ b/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php
@@ -140,7 +140,7 @@ class MediaUiFunctionalTest extends MediaFunctionalTestBase {
     $assert_session->pageTextContains('This action cannot be undone');
     $page->pressButton('Delete');
     $media_id = \Drupal::entityQuery('media')->execute();
-    $this->assertFalse($media_id);
+    $this->assertEmpty($media_id);
   }
 
   /**
diff --git a/core/modules/media/tests/src/FunctionalJavascript/MediaViewsWizardTest.php b/core/modules/media/tests/src/FunctionalJavascript/MediaViewsWizardTest.php
index aafa2884e4b..4ebe977e505 100644
--- a/core/modules/media/tests/src/FunctionalJavascript/MediaViewsWizardTest.php
+++ b/core/modules/media/tests/src/FunctionalJavascript/MediaViewsWizardTest.php
@@ -48,7 +48,7 @@ class MediaViewsWizardTest extends MediaJavascriptTestBase {
     // Check for the default filters.
     $this->assertSame($view->filter['status']->table, 'media_field_data');
     $this->assertSame($view->filter['status']->field, 'status');
-    $this->assertTrue($view->filter['status']->value);
+    $this->assertSame($view->filter['status']->value, '1');
     // Check for the default fields.
     $this->assertSame($view->field['name']->table, 'media_field_data');
     $this->assertSame($view->field['name']->field, 'name');
@@ -82,7 +82,7 @@ class MediaViewsWizardTest extends MediaJavascriptTestBase {
     // Check for the default filters.
     $this->assertSame($view->filter['status']->table, 'media_field_revision');
     $this->assertSame($view->filter['status']->field, 'status');
-    $this->assertTrue($view->filter['status']->value);
+    $this->assertSame($view->filter['status']->value, '1');
 
     // Check for the default fields.
     $this->assertSame($view->field['name']->table, 'media_field_revision');
diff --git a/core/modules/media_library/tests/src/FunctionalJavascript/EmbeddedFormWidgetTest.php b/core/modules/media_library/tests/src/FunctionalJavascript/EmbeddedFormWidgetTest.php
index 3eacc698ff2..eac555c4194 100644
--- a/core/modules/media_library/tests/src/FunctionalJavascript/EmbeddedFormWidgetTest.php
+++ b/core/modules/media_library/tests/src/FunctionalJavascript/EmbeddedFormWidgetTest.php
@@ -121,13 +121,13 @@ class EmbeddedFormWidgetTest extends WebDriverTestBase {
     $this->drupalGet('node/add/basic_page');
     $wrapper = $assert_session->elementExists('css', '#media_image_field-media-library-wrapper');
     $wrapper->pressButton('Add media');
-    $this->assertTrue($assert_session->waitForText('Add or select media'));
+    $this->assertNotNull($assert_session->waitForText('Add or select media'));
     $page->attachFileToField('Add file', $this->container->get('file_system')->realpath($jpg_image->uri));
-    $this->assertTrue($assert_session->waitForText('Alternative text'));
+    $this->assertNotNull($assert_session->waitForText('Alternative text'));
     $page->fillField('Alternative text', $this->randomString());
     $assert_session->elementExists('css', '.ui-dialog-buttonpane')->pressButton('Save and insert');
     $first_item_locator = "(//div[@data-drupal-selector='edit-media-image-field-selection-0'])[1]";
-    $this->assertTrue($first_item = $assert_session->waitForElementVisible('xpath', $first_item_locator));
+    $this->assertNotNull($first_item = $assert_session->waitForElementVisible('xpath', $first_item_locator));
     $first_item->pressButton('Remove');
     $assert_session->waitForElementRemoved('xpath', $first_item_locator);
     $page->waitFor(10, function () use ($wrapper) {
@@ -135,11 +135,11 @@ class EmbeddedFormWidgetTest extends WebDriverTestBase {
     });
     // Test reinserting the same selection.
     $wrapper->pressButton('Add media');
-    $this->assertTrue($assert_session->waitForText('Add or select media'));
+    $this->assertNotNull($assert_session->waitForText('Add or select media'));
     $assert_session->elementExists('xpath', "(//div[contains(@class, 'media-library-item')])[1]")->click();
     $assert_session->checkboxChecked('media_library_select_form[0]');
     $assert_session->elementExists('css', '.ui-dialog-buttonpane')->pressButton('Insert selected');
-    $this->assertTrue($assert_session->waitForElementVisible('xpath', $first_item_locator));
+    $this->assertNotNull($assert_session->waitForElementVisible('xpath', $first_item_locator));
   }
 
   /**
diff --git a/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php b/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php
index 87b593f99c3..c5f436e5d4a 100644
--- a/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php
+++ b/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php
@@ -2002,7 +2002,7 @@ class MediaLibraryTest extends WebDriverTestBase {
 
     $this->drupalGet('/admin/structure/types/manage/article/fields/add-field');
     $page->selectFieldOption('new_storage_type', 'field_ui:entity_reference:media');
-    $this->assertTrue($assert_session->waitForField('label'));
+    $this->assertNotNull($assert_session->waitForField('label'));
     $page->fillField('label', 'Shatner');
     $this->waitForText('field_shatner');
     $page->pressButton('Save and continue');
diff --git a/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php b/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php
index f205ed794f7..128cd4195ee 100644
--- a/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php
+++ b/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php
@@ -81,7 +81,7 @@ class MenuLinkContentFormTest extends BrowserTestBase {
   public function testMenuLinkContentForm() {
     $this->drupalGet('admin/structure/menu/manage/admin/add');
     $element = $this->xpath('//select[@id = :id]/option[@selected]', [':id' => 'edit-menu-parent']);
-    $this->assertTrue($element, 'A default menu parent was found.');
+    $this->assertNotEmpty($element, 'A default menu parent was found.');
     $this->assertEqual('admin:', $element[0]->getValue(), '<Administration> menu is the parent.');
     // Test that the field description is present.
     $this->assertRaw('The location this menu link points to.');
diff --git a/core/modules/menu_link_content/tests/src/Kernel/Migrate/d7/MigrateMenuLinkTest.php b/core/modules/menu_link_content/tests/src/Kernel/Migrate/d7/MigrateMenuLinkTest.php
index eebe4276124..36904bd5f4d 100644
--- a/core/modules/menu_link_content/tests/src/Kernel/Migrate/d7/MigrateMenuLinkTest.php
+++ b/core/modules/menu_link_content/tests/src/Kernel/Migrate/d7/MigrateMenuLinkTest.php
@@ -131,7 +131,7 @@ class MigrateMenuLinkTest extends MigrateDrupal7TestBase {
     $tree = $menu_link_tree_service->load(static::MENU_NAME, $parameters);
     $found = FALSE;
     foreach ($tree as $menu_link_tree_element) {
-      $this->assertTrue($menu_link_tree_element->link->getUrlObject()->toString());
+      $this->assertNotEmpty($menu_link_tree_element->link->getUrlObject()->toString());
       if ($menu_link_tree_element->link->getTitle() == 'custom link test') {
         $found = TRUE;
         break;
diff --git a/core/modules/menu_ui/tests/src/Functional/MenuUiNodeTest.php b/core/modules/menu_ui/tests/src/Functional/MenuUiNodeTest.php
index df6a47951df..c1392b01361 100644
--- a/core/modules/menu_ui/tests/src/Functional/MenuUiNodeTest.php
+++ b/core/modules/menu_ui/tests/src/Functional/MenuUiNodeTest.php
@@ -222,7 +222,7 @@ class MenuUiNodeTest extends BrowserTestBase {
     // Assert that the link is still in the Administration menu after save.
     $this->drupalPostForm('node/' . $node->id() . '/edit', $edit, t('Save'));
     $link = MenuLinkContent::load($item->id());
-    $this->assertTrue($link, 'Link in not allowed menu still exists after saving node');
+    $this->assertInstanceOf(MenuLinkContent::class, $link, 'Link in not allowed menu still exists after saving node');
 
     // Move the menu link back to the Tools menu.
     $item->menu_name->value = 'tools';
diff --git a/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php b/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php
index 69114430f29..d04075d004b 100644
--- a/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php
+++ b/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php
@@ -260,7 +260,7 @@ class MenuUiTest extends BrowserTestBase {
     // Test if all menu links associated with the menu were removed from
     // database.
     $result = \Drupal::entityTypeManager()->getStorage('menu_link_content')->loadByProperties(['menu_name' => $menu_name]);
-    $this->assertFalse($result, 'All menu links associated with the custom menu were deleted.');
+    $this->assertEmpty($result, 'All menu links associated with the custom menu were deleted.');
 
     // Make sure there's no delete button on system menus.
     $this->drupalGet('admin/structure/menu/manage/main');
@@ -620,7 +620,7 @@ class MenuUiTest extends BrowserTestBase {
     $menu_links = \Drupal::entityTypeManager()->getStorage('menu_link_content')->loadByProperties(['title' => $title]);
 
     $menu_link = reset($menu_links);
-    $this->assertTrue($menu_link, 'Menu link was found in database.');
+    $this->assertInstanceOf(MenuLinkContent::class, $menu_link, 'Menu link was found in database.');
     $this->assertMenuLink(['menu_name' => $menu_name, 'children' => [], 'parent' => $parent], $menu_link->getPluginId());
 
     return $menu_link;
@@ -1032,8 +1032,7 @@ class MenuUiTest extends BrowserTestBase {
     // Check that the menu overview form can be saved without errors when there
     // are pending revisions.
     $this->drupalPostForm('admin/structure/menu/manage/' . $menu_2->id(), [], 'Save');
-    $errors = $this->xpath('//div[contains(@class, "messages--error")]');
-    $this->assertFalse($errors, 'Menu overview form saved without errors.');
+    $this->assertSession()->elementNotExists('xpath', '//div[contains(@class, "messages--error")]');
   }
 
 }
diff --git a/core/modules/menu_ui/tests/src/Functional/MenuUninstallTest.php b/core/modules/menu_ui/tests/src/Functional/MenuUninstallTest.php
index 0415ac9a504..c176c518757 100644
--- a/core/modules/menu_ui/tests/src/Functional/MenuUninstallTest.php
+++ b/core/modules/menu_ui/tests/src/Functional/MenuUninstallTest.php
@@ -32,7 +32,7 @@ class MenuUninstallTest extends BrowserTestBase {
 
     \Drupal::entityTypeManager()->getStorage('menu')->resetCache(['admin']);
 
-    $this->assertTrue(Menu::load('admin'), 'The \'admin\' menu still exists after uninstalling Menu UI module.');
+    $this->assertNotEmpty(Menu::load('admin'), 'The \'admin\' menu still exists after uninstalling Menu UI module.');
   }
 
 }
diff --git a/core/modules/migrate/tests/src/Kernel/MigrateEntityContentBaseTest.php b/core/modules/migrate/tests/src/Kernel/MigrateEntityContentBaseTest.php
index 8ae0ca89c70..24eecfcba65 100644
--- a/core/modules/migrate/tests/src/Kernel/MigrateEntityContentBaseTest.php
+++ b/core/modules/migrate/tests/src/Kernel/MigrateEntityContentBaseTest.php
@@ -70,7 +70,7 @@ class MigrateEntityContentBaseTest extends KernelTestBase {
    */
   protected function assertTranslations($id, $default, $others = []) {
     $entity = $this->storage->load($id);
-    $this->assertTrue($entity, "Entity exists");
+    $this->assertNotEmpty($entity, "Entity exists");
     $this->assertEquals($default, $entity->language()->getId(), "Entity default translation");
     $translations = array_keys($entity->getTranslationLanguages(FALSE));
     sort($others);
@@ -115,7 +115,7 @@ class MigrateEntityContentBaseTest extends KernelTestBase {
     $this->assertTranslations(1, 'en');
     $this->assertTranslations(2, 'fr');
     $this->assertTranslations(3, 'en', ['fr']);
-    $this->assertFalse($this->storage->load(4));
+    $this->assertNull($this->storage->load(4));
 
     $destination_rows = [
       // Existing default translation.
diff --git a/core/modules/migrate/tests/src/Kernel/MigrateRollbackEntityConfigTest.php b/core/modules/migrate/tests/src/Kernel/MigrateRollbackEntityConfigTest.php
index 04342aebd7f..23ab7481dd2 100644
--- a/core/modules/migrate/tests/src/Kernel/MigrateRollbackEntityConfigTest.php
+++ b/core/modules/migrate/tests/src/Kernel/MigrateRollbackEntityConfigTest.php
@@ -71,7 +71,7 @@ class MigrateRollbackEntityConfigTest extends MigrateTestBase {
     foreach ($vocabulary_data_rows as $row) {
       /** @var \Drupal\taxonomy\Entity\Vocabulary $vocabulary */
       $vocabulary = Vocabulary::load($row['id']);
-      $this->assertTrue($vocabulary);
+      $this->assertNotEmpty($vocabulary);
       $map_row = $vocabulary_id_map->getRowBySource(['id' => $row['id']]);
       $this->assertNotNull($map_row['destid1']);
     }
@@ -159,7 +159,7 @@ class MigrateRollbackEntityConfigTest extends MigrateTestBase {
     foreach ($vocabulary_data_rows as $row) {
       /** @var \Drupal\taxonomy\Entity\Vocabulary $vocabulary */
       $vocabulary = Vocabulary::load($row['id']);
-      $this->assertTrue($vocabulary);
+      $this->assertNotEmpty($vocabulary);
       $map_row = $vocabulary_id_map->getRowBySource(['id' => $row['id']]);
       $this->assertNotNull($map_row['destid1']);
     }
diff --git a/core/modules/migrate/tests/src/Kernel/MigrateRollbackTest.php b/core/modules/migrate/tests/src/Kernel/MigrateRollbackTest.php
index 9d517b1dd4c..c772c8a27ef 100644
--- a/core/modules/migrate/tests/src/Kernel/MigrateRollbackTest.php
+++ b/core/modules/migrate/tests/src/Kernel/MigrateRollbackTest.php
@@ -71,7 +71,7 @@ class MigrateRollbackTest extends MigrateTestBase {
     foreach ($vocabulary_data_rows as $row) {
       /** @var \Drupal\taxonomy\Entity\Vocabulary $vocabulary */
       $vocabulary = Vocabulary::load($row['id']);
-      $this->assertTrue($vocabulary);
+      $this->assertNotEmpty($vocabulary);
       $map_row = $vocabulary_id_map->getRowBySource(['id' => $row['id']]);
       $this->assertNotNull($map_row['destid1']);
     }
@@ -124,7 +124,7 @@ class MigrateRollbackTest extends MigrateTestBase {
     foreach ($term_data_rows as $row) {
       /** @var \Drupal\taxonomy\Entity\Term $term */
       $term = Term::load($row['id']);
-      $this->assertTrue($term);
+      $this->assertNotEmpty($term);
       $map_row = $term_id_map->getRowBySource(['id' => $row['id']]);
       $this->assertNotNull($map_row['destid1']);
     }
diff --git a/core/modules/migrate_drupal/src/Tests/StubTestTrait.php b/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
index 5a5fa043325..79a2a0fef16 100644
--- a/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
+++ b/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
@@ -18,7 +18,7 @@ trait StubTestTrait {
    */
   protected function performStubTest($entity_type_id) {
     $entity_id = $this->createStub($entity_type_id);
-    $this->assertTrue($entity_id, 'Stub successfully created');
+    $this->assertNotEmpty($entity_id, 'Stub successfully created');
     if ($entity_id) {
       $violations = $this->validateStub($entity_type_id, $entity_id);
       if (!$this->assertIdentical(count($violations), 0, 'Stub is a valid entity')) {
diff --git a/core/modules/node/tests/src/Functional/NodeAccessBaseTableTest.php b/core/modules/node/tests/src/Functional/NodeAccessBaseTableTest.php
index 4434b0dfe28..1cc590eb758 100644
--- a/core/modules/node/tests/src/Functional/NodeAccessBaseTableTest.php
+++ b/core/modules/node/tests/src/Functional/NodeAccessBaseTableTest.php
@@ -131,8 +131,8 @@ class NodeAccessBaseTableTest extends NodeTestBase {
     $connection = Database::getConnection();
     $this->publicTid = $connection->query('SELECT tid FROM {taxonomy_term_field_data} WHERE name = :name AND default_langcode = 1', [':name' => 'public'])->fetchField();
     $this->privateTid = $connection->query('SELECT tid FROM {taxonomy_term_field_data} WHERE name = :name AND default_langcode = 1', [':name' => 'private'])->fetchField();
-    $this->assertTrue($this->publicTid, 'Public tid was found');
-    $this->assertTrue($this->privateTid, 'Private tid was found');
+    $this->assertNotEmpty($this->publicTid, 'Public tid was found');
+    $this->assertNotEmpty($this->privateTid, 'Private tid was found');
     foreach ($simple_users as $this->webUser) {
       $this->drupalLogin($this->webUser);
       // Check own nodes to see that all are readable.
@@ -205,7 +205,7 @@ class NodeAccessBaseTableTest extends NodeTestBase {
       $this->nidsVisible = [];
       foreach ($this->xpath("//a[text()='Read more']") as $link) {
         // See also testTranslationRendering() in NodeTranslationUITest.
-        $this->assertTrue(preg_match('|node/(\d+)$|', $link->getAttribute('href'), $matches), 'Read more points to a node');
+        $this->assertEquals(1, preg_match('|node/(\d+)$|', $link->getAttribute('href'), $matches), 'Read more points to a node');
         $this->nidsVisible[$matches[1]] = TRUE;
       }
       foreach ($this->nodesByUser as $uid => $data) {
diff --git a/core/modules/node/tests/src/Functional/NodeAccessPagerTest.php b/core/modules/node/tests/src/Functional/NodeAccessPagerTest.php
index ba993d46ef2..76acb9f9f49 100644
--- a/core/modules/node/tests/src/Functional/NodeAccessPagerTest.php
+++ b/core/modules/node/tests/src/Functional/NodeAccessPagerTest.php
@@ -76,12 +76,12 @@ class NodeAccessPagerTest extends BrowserTestBase {
   public function testForumPager() {
     // Look up the forums vocabulary ID.
     $vid = $this->config('forum.settings')->get('vocabulary');
-    $this->assertTrue($vid, 'Forum navigation vocabulary ID is set.');
+    $this->assertNotEmpty($vid, 'Forum navigation vocabulary ID is set.');
 
     // Look up the general discussion term.
     $tree = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadTree($vid, 0, 1);
     $tid = reset($tree)->tid;
-    $this->assertTrue($tid, 'General discussion term is found in the forum vocabulary.');
+    $this->assertNotEmpty($tid, 'General discussion term is found in the forum vocabulary.');
 
     // Create 30 nodes.
     for ($i = 0; $i < 30; $i++) {
diff --git a/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php b/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php
index 0e2c6e33dfb..8c61404b8dc 100644
--- a/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php
+++ b/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php
@@ -65,7 +65,7 @@ class NodeAccessRebuildNodeGrantsTest extends NodeTestBase {
     $grant_storage = \Drupal::service('node.grant_storage');
     // Default realm access and node records are present.
     foreach ($nodes as $node) {
-      $this->assertTrue($node->private->value);
+      $this->assertNotEmpty($node->private->value);
       $this->assertTrue($grant_storage->access($node, 'view', $this->webUser)->isAllowed(), 'Prior to rebuilding node access the grant storage returns allowed for the node author.');
       $this->assertTrue($grant_storage->access($node, 'view', $this->adminUser)->isAllowed(), 'Prior to rebuilding node access the grant storage returns allowed for the admin user.');
     }
@@ -87,7 +87,7 @@ class NodeAccessRebuildNodeGrantsTest extends NodeTestBase {
       $this->assertTrue($grant_storage->access($node, 'view', $this->webUser)->isAllowed(), 'After rebuilding node access the grant storage returns allowed for the node author.');
       $this->assertFalse($grant_storage->access($node, 'view', $this->adminUser)->isForbidden(), 'After rebuilding node access the grant storage returns forbidden for the admin user.');
     }
-    $this->assertFalse(\Drupal::service('node.grant_storage')->checkAll($this->webUser), 'There is no all realm access record');
+    $this->assertEmpty(\Drupal::service('node.grant_storage')->checkAll($this->webUser), 'There is no all realm access record');
 
     // Test an anonymous node access rebuild from code.
     $this->drupalLogout();
@@ -96,7 +96,7 @@ class NodeAccessRebuildNodeGrantsTest extends NodeTestBase {
       $this->assertTrue($grant_storage->access($node, 'view', $this->webUser)->isAllowed(), 'After rebuilding node access the grant storage returns allowed for the node author.');
       $this->assertFalse($grant_storage->access($node, 'view', $this->adminUser)->isForbidden(), 'After rebuilding node access the grant storage returns forbidden for the admin user.');
     }
-    $this->assertFalse(\Drupal::service('node.grant_storage')->checkAll($this->webUser), 'There is no all realm access record');
+    $this->assertEmpty(\Drupal::service('node.grant_storage')->checkAll($this->webUser), 'There is no all realm access record');
   }
 
   /**
@@ -107,7 +107,7 @@ class NodeAccessRebuildNodeGrantsTest extends NodeTestBase {
     $this->assertEqual(1, \Drupal::service('node.grant_storage')->count(), 'There is an all realm access record');
 
     // No need to rebuild permissions.
-    $this->assertFalse(\Drupal::state()->get('node.node_access_needs_rebuild'), 'Node access permissions need to be rebuilt');
+    $this->assertNull(\Drupal::state()->get('node.node_access_needs_rebuild'), 'Node access permissions need to be rebuilt');
 
     // Rebuild permissions.
     $this->drupalGet('admin/reports/status');
diff --git a/core/modules/node/tests/src/Functional/NodeActionsConfigurationTest.php b/core/modules/node/tests/src/Functional/NodeActionsConfigurationTest.php
index a93ffb06594..c9f0949694e 100644
--- a/core/modules/node/tests/src/Functional/NodeActionsConfigurationTest.php
+++ b/core/modules/node/tests/src/Functional/NodeActionsConfigurationTest.php
@@ -82,7 +82,7 @@ class NodeActionsConfigurationTest extends BrowserTestBase {
     $this->assertNoText($new_action_label, 'The label for the node_assign_owner_action action does not appear on the actions administration page after deleting.');
 
     $action = Action::load($action_id);
-    $this->assertFalse($action, 'The node_assign_owner_action action is not available after being deleted.');
+    $this->assertNull($action, 'The node_assign_owner_action action is not available after being deleted.');
   }
 
 }
diff --git a/core/modules/node/tests/src/Functional/NodeBlockFunctionalTest.php b/core/modules/node/tests/src/Functional/NodeBlockFunctionalTest.php
index dc0dfb2ab5f..b0b0aae17bb 100644
--- a/core/modules/node/tests/src/Functional/NodeBlockFunctionalTest.php
+++ b/core/modules/node/tests/src/Functional/NodeBlockFunctionalTest.php
@@ -103,7 +103,7 @@ class NodeBlockFunctionalTest extends NodeTestBase {
     $this->assertText($node3->label(), 'Node found in block.');
 
     // Check to make sure nodes are in the right order.
-    $this->assertTrue($this->xpath('//div[@id="block-test-block"]//div[@class="item-list"]/ul/li[1]/div/span/a[text() = "' . $node3->label() . '"]'), 'Nodes were ordered correctly in block.');
+    $this->assertNotEmpty($this->xpath('//div[@id="block-test-block"]//div[@class="item-list"]/ul/li[1]/div/span/a[text() = "' . $node3->label() . '"]'), 'Nodes were ordered correctly in block.');
 
     $this->drupalLogout();
     $this->drupalLogin($this->adminUser);
diff --git a/core/modules/node/tests/src/Functional/NodeCreationTest.php b/core/modules/node/tests/src/Functional/NodeCreationTest.php
index fd1e2cbd676..c64ace0afec 100644
--- a/core/modules/node/tests/src/Functional/NodeCreationTest.php
+++ b/core/modules/node/tests/src/Functional/NodeCreationTest.php
@@ -61,7 +61,7 @@ class NodeCreationTest extends NodeTestBase {
 
     // Check that the node exists in the database.
     $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertNotEmpty($node, 'Node found in database.');
 
     // Verify that pages do not show submitted information by default.
     $this->drupalGet('node/' . $node->id());
diff --git a/core/modules/node/tests/src/Functional/NodeEditFormTest.php b/core/modules/node/tests/src/Functional/NodeEditFormTest.php
index b4dcc31ba8e..62d0a610065 100644
--- a/core/modules/node/tests/src/Functional/NodeEditFormTest.php
+++ b/core/modules/node/tests/src/Functional/NodeEditFormTest.php
@@ -71,7 +71,7 @@ class NodeEditFormTest extends NodeTestBase {
 
     // Check that the node exists in the database.
     $node = $this->drupalGetNodeByTitle($edit[$title_key]);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertNotEmpty($node, 'Node found in database.');
 
     // Check that "edit" link points to correct page.
     $this->clickLink(t('Edit'));
diff --git a/core/modules/node/tests/src/Functional/NodeFieldMultilingualTest.php b/core/modules/node/tests/src/Functional/NodeFieldMultilingualTest.php
index 7b77d5c6277..2d1f97472de 100644
--- a/core/modules/node/tests/src/Functional/NodeFieldMultilingualTest.php
+++ b/core/modules/node/tests/src/Functional/NodeFieldMultilingualTest.php
@@ -76,7 +76,7 @@ class NodeFieldMultilingualTest extends BrowserTestBase {
 
     // Check that the node exists in the database.
     $node = $this->drupalGetNodeByTitle($edit[$title_key]);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertNotEmpty($node, 'Node found in database.');
     $this->assertTrue($node->language()->getId() == $langcode && $node->body->value == $body_value, 'Field language correctly set.');
 
     // Change node language.
@@ -88,7 +88,7 @@ class NodeFieldMultilingualTest extends BrowserTestBase {
     ];
     $this->drupalPostForm(NULL, $edit, t('Save'));
     $node = $this->drupalGetNodeByTitle($edit[$title_key], TRUE);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertNotEmpty($node, 'Node found in database.');
     $this->assertTrue($node->language()->getId() == $langcode && $node->body->value == $body_value, 'Field language correctly changed.');
 
     // Enable content language URL detection.
@@ -120,7 +120,7 @@ class NodeFieldMultilingualTest extends BrowserTestBase {
 
     // Check that the node exists in the database.
     $node = $this->drupalGetNodeByTitle($edit[$title_key]);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertNotEmpty($node, 'Node found in database.');
 
     // Check if node body is showed.
     $this->drupalGet('node/' . $node->id());
diff --git a/core/modules/node/tests/src/Functional/NodeSaveTest.php b/core/modules/node/tests/src/Functional/NodeSaveTest.php
index d0583b9a4be..c4b5243f720 100644
--- a/core/modules/node/tests/src/Functional/NodeSaveTest.php
+++ b/core/modules/node/tests/src/Functional/NodeSaveTest.php
@@ -72,10 +72,10 @@ class NodeSaveTest extends NodeTestBase {
     $node->save();
     // Test the import.
     $node_by_nid = Node::load($test_nid);
-    $this->assertTrue($node_by_nid, 'Node load by node ID.');
+    $this->assertNotEmpty($node_by_nid, 'Node load by node ID.');
 
     $node_by_title = $this->drupalGetNodeByTitle($title);
-    $this->assertTrue($node_by_title, 'Node load by node title.');
+    $this->assertNotEmpty($node_by_title, 'Node load by node title.');
   }
 
   /**
diff --git a/core/modules/node/tests/src/Functional/NodeTypeInitialLanguageTest.php b/core/modules/node/tests/src/Functional/NodeTypeInitialLanguageTest.php
index 70141772ebd..8d970e7d9a3 100644
--- a/core/modules/node/tests/src/Functional/NodeTypeInitialLanguageTest.php
+++ b/core/modules/node/tests/src/Functional/NodeTypeInitialLanguageTest.php
@@ -102,7 +102,7 @@ class NodeTypeInitialLanguageTest extends NodeTestBase {
     ];
     $this->drupalPostForm('node/add/article', $edit, t('Save'));
     $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertNotEmpty($node, 'Node found in database.');
 
     // Loads node page and check if Language field is hidden by default.
     $this->drupalGet('node/' . $node->id());
diff --git a/core/modules/node/tests/src/Functional/NodeViewTest.php b/core/modules/node/tests/src/Functional/NodeViewTest.php
index 708adb59d64..19bb251fd57 100644
--- a/core/modules/node/tests/src/Functional/NodeViewTest.php
+++ b/core/modules/node/tests/src/Functional/NodeViewTest.php
@@ -30,10 +30,10 @@ class NodeViewTest extends NodeTestBase {
 
     // Link relations are checked for access for anonymous users.
     $result = $this->xpath('//link[@rel = "version-history"]');
-    $this->assertFalse($result, 'Version history not present for anonymous users without access.');
+    $this->assertEmpty($result, 'Version history not present for anonymous users without access.');
 
     $result = $this->xpath('//link[@rel = "edit-form"]');
-    $this->assertFalse($result, 'Edit form not present for anonymous users without access.');
+    $this->assertEmpty($result, 'Edit form not present for anonymous users without access.');
 
     $this->drupalLogin($this->createUser(['access content']));
     $this->drupalGet($node->toUrl());
@@ -64,7 +64,7 @@ class NodeViewTest extends NodeTestBase {
     $this->assertEqual($result[0]->getAttribute('href'), $node->toUrl()->setAbsolute()->toString());
 
     $result = $this->xpath('//link[@rel = "version-history"]');
-    $this->assertFalse($result, 'Version history not present for anonymous users without access.');
+    $this->assertEmpty($result, 'Version history not present for anonymous users without access.');
 
     $result = $this->xpath('//link[@rel = "edit-form"]');
     $this->assertEqual($result[0]->getAttribute('href'), $node->toUrl('edit-form')->setAbsolute()->toString());
diff --git a/core/modules/node/tests/src/Functional/PageViewTest.php b/core/modules/node/tests/src/Functional/PageViewTest.php
index 30a8dbdfc0b..63ac3f73358 100644
--- a/core/modules/node/tests/src/Functional/PageViewTest.php
+++ b/core/modules/node/tests/src/Functional/PageViewTest.php
@@ -22,7 +22,7 @@ class PageViewTest extends NodeTestBase {
   public function testPageView() {
     // Create a node to view.
     $node = $this->drupalCreateNode();
-    $this->assertTrue(Node::load($node->id()), 'Node created.');
+    $this->assertNotEmpty(Node::load($node->id()), 'Node created.');
 
     // Try to edit with anonymous user.
     $this->drupalGet("node/" . $node->id() . "/edit");
diff --git a/core/modules/node/tests/src/Functional/Views/BulkFormTest.php b/core/modules/node/tests/src/Functional/Views/BulkFormTest.php
index 1ff8c65f828..92eabee8a11 100644
--- a/core/modules/node/tests/src/Functional/Views/BulkFormTest.php
+++ b/core/modules/node/tests/src/Functional/Views/BulkFormTest.php
@@ -276,7 +276,7 @@ class BulkFormTest extends NodeTestBase {
     $node = $this->loadNode(4);
     $this->assertNull($node, '4: Node has been deleted');
     $node = $this->loadNode(5);
-    $this->assertTrue($node, '5: Node has not been deleted');
+    $this->assertNotEmpty($node, '5: Node has not been deleted');
 
     $this->assertText('Deleted 8 content items.');
   }
diff --git a/core/modules/node/tests/src/Functional/Views/FrontPageTest.php b/core/modules/node/tests/src/Functional/Views/FrontPageTest.php
index b7eed140851..5671d1ead84 100644
--- a/core/modules/node/tests/src/Functional/Views/FrontPageTest.php
+++ b/core/modules/node/tests/src/Functional/Views/FrontPageTest.php
@@ -171,7 +171,7 @@ class FrontPageTest extends ViewTestBase {
     $found_nids = array_filter($view->result, function ($row) use ($not_expected_nids) {
       return in_array($row->nid, $not_expected_nids);
     });
-    $this->assertFalse($found_nids, $message);
+    $this->assertEmpty($found_nids, $message);
   }
 
   /**
diff --git a/core/modules/node/tests/src/Functional/Views/NodeRevisionWizardTest.php b/core/modules/node/tests/src/Functional/Views/NodeRevisionWizardTest.php
index ba2a0c60a8f..b7af626a064 100644
--- a/core/modules/node/tests/src/Functional/Views/NodeRevisionWizardTest.php
+++ b/core/modules/node/tests/src/Functional/Views/NodeRevisionWizardTest.php
@@ -73,7 +73,7 @@ class NodeRevisionWizardTest extends WizardTestBase {
     // Check for the default filters.
     $this->assertEqual($view->filter['status']->table, 'node_field_revision');
     $this->assertEqual($view->filter['status']->field, 'status');
-    $this->assertTrue($view->filter['status']->value);
+    $this->assertEquals('1', $view->filter['status']->value);
     $this->assertEquals('node_field_data', $view->filter['type']->table);
 
     $this->executeView($view);
@@ -107,8 +107,8 @@ class NodeRevisionWizardTest extends WizardTestBase {
     // Check for the default filters.
     $this->assertEqual($view->filter['status']->table, 'node_field_revision');
     $this->assertEqual($view->filter['status']->field, 'status');
-    $this->assertTrue($view->filter['status']->value);
-    $this->assertTrue(empty($view->filter['type']));
+    $this->assertEquals('1', $view->filter['status']->value);
+    $this->assertArrayNotHasKey('type', $view->filter);
 
     $this->executeView($view);
 
diff --git a/core/modules/node/tests/src/Kernel/Config/NodeImportCreateTest.php b/core/modules/node/tests/src/Kernel/Config/NodeImportCreateTest.php
index 66b41db3544..342651522ec 100644
--- a/core/modules/node/tests/src/Kernel/Config/NodeImportCreateTest.php
+++ b/core/modules/node/tests/src/Kernel/Config/NodeImportCreateTest.php
@@ -39,13 +39,13 @@ class NodeImportCreateTest extends KernelTestBase {
     $node_type_id = 'default';
 
     // Check that the content type does not exist yet.
-    $this->assertFalse(NodeType::load($node_type_id));
+    $this->assertNull(NodeType::load($node_type_id));
 
     // Enable node_test_config module and check that the content type
     // shipped in the module's default config is created.
     $this->container->get('module_installer')->install(['node_test_config']);
     $node_type = NodeType::load($node_type_id);
-    $this->assertTrue($node_type, 'The default content type was created.');
+    $this->assertNotEmpty($node_type, 'The default content type was created.');
   }
 
   /**
@@ -62,15 +62,15 @@ class NodeImportCreateTest extends KernelTestBase {
     // Manually add new node type.
     $src_dir = __DIR__ . '/../../../modules/node_test_config/sync';
     $target_dir = Settings::get('config_sync_directory');
-    $this->assertTrue(\Drupal::service('file_system')->copy("$src_dir/$node_type_config_name.yml", "$target_dir/$node_type_config_name.yml"));
+    $this->assertNotFalse(\Drupal::service('file_system')->copy("$src_dir/$node_type_config_name.yml", "$target_dir/$node_type_config_name.yml"));
 
     // Import the content of the sync directory.
     $this->configImporter()->import();
 
     // Check that the content type was created.
     $node_type = NodeType::load($node_type_id);
-    $this->assertTrue($node_type, 'Import node type from sync was created.');
-    $this->assertFalse(FieldConfig::loadByName('node', $node_type_id, 'body'));
+    $this->assertNotEmpty($node_type, 'Import node type from sync was created.');
+    $this->assertNull(FieldConfig::loadByName('node', $node_type_id, 'body'));
   }
 
 }
diff --git a/core/modules/node/tests/src/Kernel/Migrate/d7/MigrateNodeTest.php b/core/modules/node/tests/src/Kernel/Migrate/d7/MigrateNodeTest.php
index 6915e4dbe4f..25aa75654fa 100644
--- a/core/modules/node/tests/src/Kernel/Migrate/d7/MigrateNodeTest.php
+++ b/core/modules/node/tests/src/Kernel/Migrate/d7/MigrateNodeTest.php
@@ -153,7 +153,7 @@ class MigrateNodeTest extends MigrateDrupal7TestBase {
     $this->assertRevision(1, 'An English Node', '1', NULL, '1441032132');
 
     $node = Node::load(1);
-    $this->assertTrue($node->field_boolean->value);
+    $this->assertNotEmpty($node->field_boolean->value);
     $this->assertEquals('99-99-99-99', $node->field_phone->value);
     $this->assertSame('2015-01-20T04:15:00', $node->field_date->value);
     $this->assertSame('2015-01-20', $node->field_date_without_time->value);
@@ -165,7 +165,7 @@ class MigrateNodeTest extends MigrateDrupal7TestBase {
     $this->assertEquals('qwerty', $node->field_text->value);
     $this->assertEquals('2', $node->field_file->target_id);
     $this->assertEquals('file desc', $node->field_file->description);
-    $this->assertTrue($node->field_file->display);
+    $this->assertNotEmpty($node->field_file->display);
     $this->assertEquals('1', $node->field_images->target_id);
     $this->assertEquals('alt text', $node->field_images->alt);
     $this->assertEquals('title text', $node->field_images->title);
diff --git a/core/modules/node/tests/src/Kernel/NodeAccessRecordsTest.php b/core/modules/node/tests/src/Kernel/NodeAccessRecordsTest.php
index 78f46710e44..714f18cb43b 100644
--- a/core/modules/node/tests/src/Kernel/NodeAccessRecordsTest.php
+++ b/core/modules/node/tests/src/Kernel/NodeAccessRecordsTest.php
@@ -26,7 +26,7 @@ class NodeAccessRecordsTest extends NodeAccessTestBase {
   public function testNodeAccessRecords() {
     // Create an article node.
     $node1 = $this->drupalCreateNode(['type' => 'article']);
-    $this->assertTrue(Node::load($node1->id()), 'Article node created.');
+    $this->assertNotEmpty(Node::load($node1->id()), 'Article node created.');
 
     // Check to see if grants added by node_test_node_access_records made it in.
     $connection = Database::getConnection();
@@ -37,7 +37,7 @@ class NodeAccessRecordsTest extends NodeAccessTestBase {
 
     // Create an unpromoted "Basic page" node.
     $node2 = $this->drupalCreateNode(['type' => 'page', 'promote' => 0]);
-    $this->assertTrue(Node::load($node2->id()), 'Unpromoted basic page node created.');
+    $this->assertNotEmpty(Node::load($node2->id()), 'Unpromoted basic page node created.');
 
     // Check to see if grants added by node_test_node_access_records made it in.
     $records = $connection->query('SELECT realm, gid FROM {node_access} WHERE nid = :nid', [':nid' => $node2->id()])->fetchAll();
@@ -47,7 +47,7 @@ class NodeAccessRecordsTest extends NodeAccessTestBase {
 
     // Create an unpromoted, unpublished "Basic page" node.
     $node3 = $this->drupalCreateNode(['type' => 'page', 'promote' => 0, 'status' => 0]);
-    $this->assertTrue(Node::load($node3->id()), 'Unpromoted, unpublished basic page node created.');
+    $this->assertNotEmpty(Node::load($node3->id()), 'Unpromoted, unpublished basic page node created.');
 
     // Check to see if grants added by node_test_node_access_records made it in.
     $records = $connection->query('SELECT realm, gid FROM {node_access} WHERE nid = :nid', [':nid' => $node3->id()])->fetchAll();
@@ -57,7 +57,7 @@ class NodeAccessRecordsTest extends NodeAccessTestBase {
 
     // Create a promoted "Basic page" node.
     $node4 = $this->drupalCreateNode(['type' => 'page', 'promote' => 1]);
-    $this->assertTrue(Node::load($node4->id()), 'Promoted basic page node created.');
+    $this->assertNotEmpty(Node::load($node4->id()), 'Promoted basic page node created.');
 
     // Check to see if grant added by node_test_node_access_records was altered
     // by node_test_node_access_records_alter.
diff --git a/core/modules/node/tests/src/Kernel/NodeBodyFieldStorageTest.php b/core/modules/node/tests/src/Kernel/NodeBodyFieldStorageTest.php
index 3dd13496d65..219618e1970 100644
--- a/core/modules/node/tests/src/Kernel/NodeBodyFieldStorageTest.php
+++ b/core/modules/node/tests/src/Kernel/NodeBodyFieldStorageTest.php
@@ -36,7 +36,7 @@ class NodeBodyFieldStorageTest extends KernelTestBase {
    */
   public function testFieldOverrides() {
     $field_storage = FieldStorageConfig::loadByName('node', 'body');
-    $this->assertTrue($field_storage, 'Node body field storage exists.');
+    $this->assertNotEmpty($field_storage, 'Node body field storage exists.');
     $type = NodeType::create(['name' => 'Ponies', 'type' => 'ponies']);
     $type->save();
     node_add_body_field($type);
@@ -48,7 +48,7 @@ class NodeBodyFieldStorageTest extends KernelTestBase {
     $this->assertTrue(count($field_storage->getBundles()) == 0, 'Node body field storage exists after deleting the only instance of a field.');
     \Drupal::service('module_installer')->uninstall(['node']);
     $field_storage = FieldStorageConfig::loadByName('node', 'body');
-    $this->assertFalse($field_storage, 'Node body field storage does not exist after uninstalling the Node module.');
+    $this->assertNull($field_storage, 'Node body field storage does not exist after uninstalling the Node module.');
   }
 
 }
diff --git a/core/modules/node/tests/src/Kernel/SummaryLengthTest.php b/core/modules/node/tests/src/Kernel/SummaryLengthTest.php
index 7a0d187ac2c..15d65a2abf5 100644
--- a/core/modules/node/tests/src/Kernel/SummaryLengthTest.php
+++ b/core/modules/node/tests/src/Kernel/SummaryLengthTest.php
@@ -86,7 +86,7 @@ class SummaryLengthTest extends KernelTestBase {
       'promote' => 1,
     ];
     $node = $this->drupalCreateNode($settings);
-    $this->assertTrue(Node::load($node->id()), 'Node created.');
+    $this->assertNotEmpty(Node::load($node->id()), 'Node created.');
 
     // Render the node as a teaser.
     $content = $this->drupalBuildEntityView($node, 'teaser');
diff --git a/core/modules/options/tests/src/Functional/OptionsSelectDynamicValuesTest.php b/core/modules/options/tests/src/Functional/OptionsSelectDynamicValuesTest.php
index 02082cb1d68..6738dbf68c9 100644
--- a/core/modules/options/tests/src/Functional/OptionsSelectDynamicValuesTest.php
+++ b/core/modules/options/tests/src/Functional/OptionsSelectDynamicValuesTest.php
@@ -32,7 +32,7 @@ class OptionsSelectDynamicValuesTest extends OptionsDynamicValuesTestBase {
     foreach ($options as $option) {
       $value = $option->getValue();
       if ($value != '_none') {
-        $this->assertTrue(array_search($value, $this->test));
+        $this->assertContains($value, $this->test);
       }
     }
   }
diff --git a/core/modules/options/tests/src/Functional/OptionsWidgetsTest.php b/core/modules/options/tests/src/Functional/OptionsWidgetsTest.php
index ff48c684c2e..5902682c038 100644
--- a/core/modules/options/tests/src/Functional/OptionsWidgetsTest.php
+++ b/core/modules/options/tests/src/Functional/OptionsWidgetsTest.php
@@ -285,7 +285,7 @@ class OptionsWidgetsTest extends FieldTestBase {
     // Display form.
     $this->drupalGet('entity_test/manage/' . $entity->id() . '/edit');
     // A required field without any value has a "none" option.
-    $this->assertTrue($this->xpath('//select[@id=:id]//option[@value="_none" and text()=:label]', [':id' => 'edit-card-1', ':label' => '- Select a value -']), 'A required select list has a "Select a value" choice.');
+    $this->assertNotEmpty($this->xpath('//select[@id=:id]//option[@value="_none" and text()=:label]', [':id' => 'edit-card-1', ':label' => '- Select a value -']), 'A required select list has a "Select a value" choice.');
 
     // With no field data, nothing is selected.
     $this->assertTrue($this->assertSession()->optionExists('card_1', '_none')->isSelected());
@@ -307,7 +307,7 @@ class OptionsWidgetsTest extends FieldTestBase {
     // Display form: check that the right options are selected.
     $this->drupalGet('entity_test/manage/' . $entity->id() . '/edit');
     // A required field with a value has no 'none' option.
-    $this->assertFalse($this->xpath('//select[@id=:id]//option[@value="_none"]', [':id' => 'edit-card-1']), 'A required select list with an actual value has no "none" choice.');
+    $this->assertEmpty($this->xpath('//select[@id=:id]//option[@value="_none"]', [':id' => 'edit-card-1']), 'A required select list with an actual value has no "none" choice.');
     $this->assertTrue($this->assertSession()->optionExists('card_1', 0)->isSelected());
     $this->assertFalse($this->assertSession()->optionExists('card_1', 1)->isSelected());
     $this->assertFalse($this->assertSession()->optionExists('card_1', 2)->isSelected());
@@ -319,7 +319,7 @@ class OptionsWidgetsTest extends FieldTestBase {
     // Display form.
     $this->drupalGet('entity_test/manage/' . $entity->id() . '/edit');
     // A non-required field has a 'none' option.
-    $this->assertTrue($this->xpath('//select[@id=:id]//option[@value="_none" and text()=:label]', [':id' => 'edit-card-1', ':label' => '- None -']), 'A non-required select list has a "None" choice.');
+    $this->assertNotEmpty($this->xpath('//select[@id=:id]//option[@value="_none" and text()=:label]', [':id' => 'edit-card-1', ':label' => '- None -']), 'A non-required select list has a "None" choice.');
     // Submit form: Unselect the option.
     $edit = ['card_1' => '_none'];
     $this->drupalPostForm('entity_test/manage/' . $entity->id() . '/edit', $edit, t('Save'));
@@ -439,7 +439,7 @@ class OptionsWidgetsTest extends FieldTestBase {
     $field->setRequired(TRUE);
     $field->save();
     $this->drupalGet('entity_test/manage/' . $entity->id() . '/edit');
-    $this->assertFalse($this->xpath('//select[@id=:id]//option[@value=""]', [':id' => 'edit-card-2']), 'A required select list does not have an empty key.');
+    $this->assertEmpty($this->xpath('//select[@id=:id]//option[@value=""]', [':id' => 'edit-card-2']), 'A required select list does not have an empty key.');
 
     // We do not have to test that a required select list with one option is
     // auto-selected because the browser does it for us.
@@ -556,8 +556,8 @@ class OptionsWidgetsTest extends FieldTestBase {
 
     // Display form: check that _none options are present and has label.
     $this->drupalGet('entity_test/manage/' . $entity->id() . '/edit');
-    $this->assertTrue($this->xpath('//div[@id=:id]//input[@value=:value]', [':id' => 'edit-card-1', ':value' => '_none']), 'A test radio button has a "None" choice.');
-    $this->assertTrue($this->xpath('//div[@id=:id]//label[@for=:for and text()=:label]', [':id' => 'edit-card-1', ':for' => 'edit-card-1-none', ':label' => 'N/A']), 'A test radio button has a "N/A" choice.');
+    $this->assertNotEmpty($this->xpath('//div[@id=:id]//input[@value=:value]', [':id' => 'edit-card-1', ':value' => '_none']), 'A test radio button has a "None" choice.');
+    $this->assertNotEmpty($this->xpath('//div[@id=:id]//label[@for=:for and text()=:label]', [':id' => 'edit-card-1', ':for' => 'edit-card-1-none', ':label' => 'N/A']), 'A test radio button has a "N/A" choice.');
 
     // Change it to the select widget.
     $display_repository->getFormDisplay('entity_test', 'entity_test')
@@ -569,7 +569,7 @@ class OptionsWidgetsTest extends FieldTestBase {
     // Display form: check that _none options are present and has label.
     $this->drupalGet('entity_test/manage/' . $entity->id() . '/edit');
     // A required field without any value has a "none" option.
-    $this->assertTrue($this->xpath('//select[@id=:id]//option[@value="_none" and text()=:label]', [':id' => 'edit-card-1', ':label' => '- None -']), 'A test select has a "None" choice.');
+    $this->assertNotEmpty($this->xpath('//select[@id=:id]//option[@value="_none" and text()=:label]', [':id' => 'edit-card-1', ':label' => '- None -']), 'A test select has a "None" choice.');
   }
 
 }
diff --git a/core/modules/page_cache/tests/src/Functional/PageCacheTest.php b/core/modules/page_cache/tests/src/Functional/PageCacheTest.php
index 553864e7b9c..fc0421de002 100644
--- a/core/modules/page_cache/tests/src/Functional/PageCacheTest.php
+++ b/core/modules/page_cache/tests/src/Functional/PageCacheTest.php
@@ -233,7 +233,7 @@ class PageCacheTest extends BrowserTestBase {
     $this->drupalLogin($user);
     $this->drupalGet('', [], ['If-Modified-Since' => $last_modified, 'If-None-Match' => $etag]);
     $this->assertResponse(200, 'Conditional request returned 200 OK for authenticated user.');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Absence of Page was not cached.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Absence of Page was not cached.');
   }
 
   /**
@@ -273,8 +273,8 @@ class PageCacheTest extends BrowserTestBase {
     $user = $this->drupalCreateUser();
     $this->drupalLogin($user);
     $this->drupalGet('system-test/set-header', ['query' => ['name' => 'Foo', 'value' => 'bar']]);
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Caching was bypassed.');
-    $this->assertTrue(strpos(strtolower($this->drupalGetHeader('Vary')), 'cookie') === FALSE, 'Vary: Cookie header was not sent.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Caching was bypassed.');
+    $this->assertNotContains('cookie', $this->drupalGetHeader('Vary'), 'Vary: Cookie header was not sent.', TRUE);
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'must-revalidate, no-cache, private', 'Cache-Control header was sent.');
     $this->assertEqual($this->drupalGetHeader('Expires'), 'Sun, 19 Nov 1978 05:00:00 GMT', 'Expires header was sent.');
     $this->assertEqual($this->drupalGetHeader('Foo'), 'bar', 'Custom header was sent.');
@@ -441,13 +441,13 @@ class PageCacheTest extends BrowserTestBase {
     // Fill the cache.
     $this->drupalGet('');
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS', 'Page was not cached.');
-    $this->assertTrue(strpos($this->drupalGetHeader('Vary'), 'Cookie') === FALSE, 'Vary: Cookie header was not sent.');
+    $this->assertNotContains('cookie', $this->drupalGetHeader('Vary'), 'Vary: Cookie header was not sent.', TRUE);
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'max-age=300, public', 'Cache-Control header was sent.');
 
     // Check cache.
     $this->drupalGet('');
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT', 'Page was cached.');
-    $this->assertTrue(strpos($this->drupalGetHeader('Vary'), 'Cookie') === FALSE, 'Vary: Cookie header was not sent.');
+    $this->assertNotContains('cookie', $this->drupalGetHeader('Vary'), 'Vary: Cookie header was not sent.', TRUE);
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'max-age=300, public', 'Cache-Control header was sent.');
   }
 
@@ -493,22 +493,22 @@ class PageCacheTest extends BrowserTestBase {
 
     // GET a URL, which would be marked as a cache miss if it were cacheable.
     $this->drupalGet('/system-test/respond-reponse');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'must-revalidate, no-cache, private', 'Cache-Control header was sent');
 
     // GET it again, verify it's still not cached.
     $this->drupalGet('/system-test/respond-reponse');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'must-revalidate, no-cache, private', 'Cache-Control header was sent');
 
     // GET a URL, which would be marked as a cache miss if it were cacheable.
     $this->drupalGet('/system-test/respond-public-response');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'max-age=60, public', 'Cache-Control header was sent');
 
     // GET it again, verify it's still not cached.
     $this->drupalGet('/system-test/respond-public-response');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
     $this->assertEqual($this->drupalGetHeader('Cache-Control'), 'max-age=60, public', 'Cache-Control header was sent');
 
     // GET a URL, which should be marked as a cache miss.
@@ -528,7 +528,7 @@ class PageCacheTest extends BrowserTestBase {
 
     // GET a URL that was cached by Page Cache before, it should not be now.
     $this->drupalGet('/respond-cacheable-reponse');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Drupal page cache header not found.');
   }
 
   /**
diff --git a/core/modules/path/tests/src/Functional/PathAliasTest.php b/core/modules/path/tests/src/Functional/PathAliasTest.php
index 4cf25f6d625..54c200873dc 100644
--- a/core/modules/path/tests/src/Functional/PathAliasTest.php
+++ b/core/modules/path/tests/src/Functional/PathAliasTest.php
@@ -57,14 +57,14 @@ class PathAliasTest extends PathTestBase {
     \Drupal::cache('data')->deleteAll();
     // Make sure the path is not converted to the alias.
     $this->drupalGet(trim($edit['path[0][value]'], '/'), ['alias' => TRUE]);
-    $this->assertTrue(\Drupal::cache('data')->get('preload-paths:' . $edit['path[0][value]']), 'Cache entry was created.');
+    $this->assertNotEmpty(\Drupal::cache('data')->get('preload-paths:' . $edit['path[0][value]']), 'Cache entry was created.');
 
     // Visit the alias for the node and confirm a cache entry is created.
     \Drupal::cache('data')->deleteAll();
     // @todo Remove this once https://www.drupal.org/node/2480077 lands.
     Cache::invalidateTags(['rendered']);
     $this->drupalGet(trim($edit['alias[0][value]'], '/'));
-    $this->assertTrue(\Drupal::cache('data')->get('preload-paths:' . $edit['path[0][value]']), 'Cache entry was created.');
+    $this->assertNotEmpty(\Drupal::cache('data')->get('preload-paths:' . $edit['path[0][value]']), 'Cache entry was created.');
   }
 
   /**
@@ -332,7 +332,7 @@ class PathAliasTest extends PathTestBase {
     // Delete the node and check that the path alias is also deleted.
     $node5->delete();
     $path_alias = \Drupal::service('path_alias.repository')->lookUpBySystemPath('/node/' . $node5->id(), $node5->language()->getId());
-    $this->assertFalse($path_alias, 'Alias was successfully deleted when the referenced node was deleted.');
+    $this->assertNull($path_alias, 'Alias was successfully deleted when the referenced node was deleted.');
 
     // Create sixth test node.
     $node6 = $this->drupalCreateNode();
diff --git a/core/modules/path/tests/src/Functional/PathLanguageTest.php b/core/modules/path/tests/src/Functional/PathLanguageTest.php
index 18a51749e44..7f2167108cb 100644
--- a/core/modules/path/tests/src/Functional/PathLanguageTest.php
+++ b/core/modules/path/tests/src/Functional/PathLanguageTest.php
@@ -124,7 +124,7 @@ class PathLanguageTest extends PathTestBase {
     $languages = $this->container->get('language_manager')->getLanguages();
     $url = $english_node_french_translation->toUrl('canonical', ['language' => $languages['fr']])->toString();
 
-    $this->assertTrue(strpos($url, $edit['path[0][alias]']), 'URL contains the path alias.');
+    $this->assertContains($edit['path[0][alias]'], $url, 'URL contains the path alias.');
 
     // Confirm that the alias works even when changing language negotiation
     // options. Enable User language detection and selection over URL one.
diff --git a/core/modules/quickedit/tests/src/Functional/QuickEditCustomPipelineTest.php b/core/modules/quickedit/tests/src/Functional/QuickEditCustomPipelineTest.php
index bde1252427f..90ae916873e 100644
--- a/core/modules/quickedit/tests/src/Functional/QuickEditCustomPipelineTest.php
+++ b/core/modules/quickedit/tests/src/Functional/QuickEditCustomPipelineTest.php
@@ -98,10 +98,10 @@ class QuickEditCustomPipelineTest extends BrowserTestBase {
     $ajax_commands = Json::decode($response->getBody());
     $this->assertIdentical(1, count($ajax_commands), 'The field form HTTP request results in one AJAX command.');
     $this->assertIdentical('quickeditFieldFormSaved', $ajax_commands[0]['command'], 'The first AJAX command is a quickeditFieldFormSaved command.');
-    $this->assertTrue(strpos($ajax_commands[0]['data'], 'Fine thanks.'), 'Form value saved and printed back.');
-    $this->assertTrue(strpos($ajax_commands[0]['data'], '<div class="quickedit-test-wrapper">') !== FALSE, 'Custom render pipeline used to render the value.');
+    $this->assertContains('Fine thanks.', $ajax_commands[0]['data'], 'Form value saved and printed back.');
+    $this->assertContains('<div class="quickedit-test-wrapper">', $ajax_commands[0]['data'], 'Custom render pipeline used to render the value.');
     $this->assertIdentical(array_keys($ajax_commands[0]['other_view_modes']), ['full'], 'Field was also rendered in the "full" view mode.');
-    $this->assertTrue(strpos($ajax_commands[0]['other_view_modes']['full'], 'Fine thanks.'), '"full" version of field contains the form value.');
+    $this->assertContains('Fine thanks.', $ajax_commands[0]['other_view_modes']['full'], '"full" version of field contains the form value.');
   }
 
 }
diff --git a/core/modules/quickedit/tests/src/FunctionalJavascript/QuickEditJavascriptTestBase.php b/core/modules/quickedit/tests/src/FunctionalJavascript/QuickEditJavascriptTestBase.php
index 8c939b3264a..8afc3242b6d 100644
--- a/core/modules/quickedit/tests/src/FunctionalJavascript/QuickEditJavascriptTestBase.php
+++ b/core/modules/quickedit/tests/src/FunctionalJavascript/QuickEditJavascriptTestBase.php
@@ -176,7 +176,7 @@ JS;
       $this->assertSame($expected_field_label, $field_label);
     }
     else {
-      $this->assertFalse($quickedit_entity_toolbar->find('css', '.quickedit-toolbar-label > .field'));
+      $this->assertEmpty($quickedit_entity_toolbar->find('css', '.quickedit-toolbar-label > .field'));
     }
   }
 
diff --git a/core/modules/rdf/tests/src/Kernel/Field/NumberFieldRdfaTest.php b/core/modules/rdf/tests/src/Kernel/Field/NumberFieldRdfaTest.php
index 22865183808..fc566cc49e6 100644
--- a/core/modules/rdf/tests/src/Kernel/Field/NumberFieldRdfaTest.php
+++ b/core/modules/rdf/tests/src/Kernel/Field/NumberFieldRdfaTest.php
@@ -23,7 +23,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is not created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__items") and @content]');
-    $this->assertFalse($result);
+    $this->assertEmpty($result);
   }
 
   /**
@@ -51,7 +51,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__item") and @content=:testValue]', [':testValue' => $testValue]);
-    $this->assertTrue($result);
+    $this->assertNotEmpty($result);
   }
 
   /**
@@ -66,7 +66,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is not created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__items") and @content]');
-    $this->assertFalse($result);
+    $this->assertEmpty($result);
   }
 
   /**
@@ -95,7 +95,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__item") and @content=:testValue]', [':testValue' => $testValue]);
-    $this->assertTrue($result);
+    $this->assertNotEmpty($result);
   }
 
   /**
@@ -116,7 +116,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is not created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__items") and @content]');
-    $this->assertFalse($result);
+    $this->assertEmpty($result);
   }
 
   /**
@@ -139,7 +139,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__item") and @content=:testValue]', [':testValue' => $testValue]);
-    $this->assertTrue($result);
+    $this->assertNotEmpty($result);
   }
 
   /**
@@ -154,7 +154,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is not created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__items") and @content]');
-    $this->assertFalse($result);
+    $this->assertEmpty($result);
   }
 
   /**
@@ -183,7 +183,7 @@ class NumberFieldRdfaTest extends FieldRdfaTestBase {
 
     // Test that the content attribute is created.
     $result = $this->xpathContent($this->getRawContent(), '//div[contains(@class, "field__item") and @content=:testValue]', [':testValue' => $testValue]);
-    $this->assertTrue($result);
+    $this->assertNotEmpty($result);
   }
 
   /**
diff --git a/core/modules/responsive_image/tests/src/Functional/ResponsiveImageAdminUITest.php b/core/modules/responsive_image/tests/src/Functional/ResponsiveImageAdminUITest.php
index 72de87c886f..68a0a2880b9 100644
--- a/core/modules/responsive_image/tests/src/Functional/ResponsiveImageAdminUITest.php
+++ b/core/modules/responsive_image/tests/src/Functional/ResponsiveImageAdminUITest.php
@@ -92,7 +92,7 @@ class ResponsiveImageAdminUITest extends BrowserTestBase {
 
       foreach ($image_styles as $image_style_name) {
         // Check if the image styles are available in the dropdowns.
-        $this->assertTrue($this->xpath(
+        $this->assertNotEmpty($this->xpath(
           '//select[@name=:name]//option[@value=:style]',
           [
             ':name' => 'keyed_styles[responsive_image_test_module.' . $case[0] . '][' . $case[1] . '][image_style]',
diff --git a/core/modules/responsive_image/tests/src/Kernel/ResponsiveImageIntegrationTest.php b/core/modules/responsive_image/tests/src/Kernel/ResponsiveImageIntegrationTest.php
index f935a4e2de2..b77edd8cc14 100644
--- a/core/modules/responsive_image/tests/src/Kernel/ResponsiveImageIntegrationTest.php
+++ b/core/modules/responsive_image/tests/src/Kernel/ResponsiveImageIntegrationTest.php
@@ -64,7 +64,7 @@ class ResponsiveImageIntegrationTest extends KernelTestBase {
 
     // Check that the 'foo' field is on the display.
     $this->assertNotNull($display = EntityViewDisplay::load('entity_test.entity_test.default'));
-    $this->assertTrue($display->getComponent('bar'));
+    $this->assertNotEmpty($display->getComponent('bar'));
     $this->assertArrayNotHasKey('bar', $display->get('hidden'));
 
     // Delete the responsive image style.
diff --git a/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php b/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
index c0de5c8578d..094d8797a60 100644
--- a/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
+++ b/core/modules/rest/tests/src/Functional/Views/StyleSerializerTest.php
@@ -327,14 +327,14 @@ class StyleSerializerTest extends ViewTestBase {
     $this->assertHeader('content-type', 'application/json');
     $this->assertCacheContexts($cache_contexts);
     $this->assertCacheTags($cache_tags);
-    $this->assertTrue($render_cache->get($original));
+    $this->assertNotEmpty($render_cache->get($original));
 
     $result_xml = $this->drupalGet('test/serialize/entity', ['query' => ['_format' => 'xml']]);
     $this->addRequestWithFormat('xml');
     $this->assertHeader('content-type', 'text/xml; charset=UTF-8');
     $this->assertCacheContexts($cache_contexts);
     $this->assertCacheTags($cache_tags);
-    $this->assertTrue($render_cache->get($original));
+    $this->assertNotEmpty($render_cache->get($original));
 
     // Ensure that the XML output is different from the JSON one.
     $this->assertNotEqual($result1, $result_xml);
@@ -346,7 +346,7 @@ class StyleSerializerTest extends ViewTestBase {
     $this->assertEqual($result2, $result1);
     $this->assertCacheContexts($cache_contexts);
     $this->assertCacheTags($cache_tags);
-    $this->assertTrue($render_cache->get($original));
+    $this->assertNotEmpty($render_cache->get($original));
 
     // Create a new entity and ensure that the cache tags are taken over.
     EntityTest::create(['name' => 'test_11', 'user_id' => $this->adminUser->id()])->save();
@@ -362,7 +362,7 @@ class StyleSerializerTest extends ViewTestBase {
 
     $this->assertCacheContexts($cache_contexts);
     $this->assertCacheTags($cache_tags);
-    $this->assertTrue($render_cache->get($original));
+    $this->assertNotEmpty($render_cache->get($original));
   }
 
   /**
diff --git a/core/modules/rest/tests/src/Kernel/Views/RestExportTest.php b/core/modules/rest/tests/src/Kernel/Views/RestExportTest.php
index f3a8f04f527..5246e484aec 100644
--- a/core/modules/rest/tests/src/Kernel/Views/RestExportTest.php
+++ b/core/modules/rest/tests/src/Kernel/Views/RestExportTest.php
@@ -51,7 +51,7 @@ class RestExportTest extends ViewsKernelTestBase {
 
     // No custom header should be set yet.
     $response = RestExport::buildResponse('test_serializer_display_entity', 'rest_export_1', []);
-    $this->assertFalse($response->headers->get('Custom-Header'));
+    $this->assertEmpty($response->headers->get('Custom-Header'));
 
     // Clear render cache.
     /** @var \Drupal\Core\Cache\MemoryBackend $render_cache */
diff --git a/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php b/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php
index fa334854870..e00eab9f8e6 100644
--- a/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php
+++ b/core/modules/search/tests/src/Functional/SearchConfigSettingsFormTest.php
@@ -117,7 +117,7 @@ class SearchConfigSettingsFormTest extends BrowserTestBase {
     $this->clickLink(t('Edit'), 1);
 
     // Ensure that the default setting was picked up from the default config
-    $this->assertTrue($this->xpath('//select[@id="edit-extra-type-settings-boost"]//option[@value="bi" and @selected="selected"]'), 'Module specific settings are picked up from the default config');
+    $this->assertSession()->elementExists('xpath', '//select[@id="edit-extra-type-settings-boost"]//option[@value="bi" and @selected="selected"]');
 
     // Change extra type setting and also modify a common search setting.
     $edit = [
@@ -128,7 +128,7 @@ class SearchConfigSettingsFormTest extends BrowserTestBase {
     // Ensure that the modifications took effect.
     $this->assertRaw(t('The %label search page has been updated.', ['%label' => 'Dummy search type']));
     $this->drupalGet('admin/config/search/pages/manage/dummy_search_type');
-    $this->assertTrue($this->xpath('//select[@id="edit-extra-type-settings-boost"]//option[@value="ii" and @selected="selected"]'), 'Module specific settings can be changed');
+    $this->assertSession()->elementExists('xpath', '//select[@id="edit-extra-type-settings-boost"]//option[@value="ii" and @selected="selected"]');
   }
 
   /**
diff --git a/core/modules/search/tests/src/Functional/SearchRankingTest.php b/core/modules/search/tests/src/Functional/SearchRankingTest.php
index 64eb1b776a0..884359b3d0b 100644
--- a/core/modules/search/tests/src/Functional/SearchRankingTest.php
+++ b/core/modules/search/tests/src/Functional/SearchRankingTest.php
@@ -125,7 +125,7 @@ class SearchRankingTest extends BrowserTestBase {
 
     // Check that all rankings are visible and set to 0.
     foreach ($node_ranks as $node_rank) {
-      $this->assertTrue($this->xpath('//select[@id="edit-rankings-' . $node_rank . '-value"]//option[@value="0"]'), 'Select list to prioritize ' . $node_rank . ' for node ranks is visible and set to 0.');
+      $this->assertNotEmpty($this->xpath('//select[@id="edit-rankings-' . $node_rank . '-value"]//option[@value="0"]'), 'Select list to prioritize ' . $node_rank . ' for node ranks is visible and set to 0.');
     }
 
     // Test each of the possible rankings.
@@ -135,7 +135,7 @@ class SearchRankingTest extends BrowserTestBase {
       $edit['rankings[' . $node_rank . '][value]'] = 10;
       $this->drupalPostForm('admin/config/search/pages/manage/node_search', $edit, t('Save search page'));
       $this->drupalGet('admin/config/search/pages/manage/node_search');
-      $this->assertTrue($this->xpath('//select[@id="edit-rankings-' . $node_rank . '-value"]//option[@value="10"]'), 'Select list to prioritize ' . $node_rank . ' for node ranks is visible and set to 10.');
+      $this->assertNotEmpty($this->xpath('//select[@id="edit-rankings-' . $node_rank . '-value"]//option[@value="10"]'), 'Select list to prioritize ' . $node_rank . ' for node ranks is visible and set to 10.');
 
       // Reload the plugin to get the up-to-date values.
       $this->nodeSearch = SearchPage::load('node_search');
@@ -153,7 +153,7 @@ class SearchRankingTest extends BrowserTestBase {
     $this->drupalPostForm('admin/config/search/pages/manage/node_search', $edit, t('Save search page'));
     $this->drupalGet('admin/config/search/pages/manage/node_search');
     foreach ($node_ranks as $node_rank) {
-      $this->assertTrue($this->xpath('//select[@id="edit-rankings-' . $node_rank . '-value"]//option[@value="0"]'), 'Select list to prioritize ' . $node_rank . ' for node ranks is visible and set to 0.');
+      $this->assertNotEmpty($this->xpath('//select[@id="edit-rankings-' . $node_rank . '-value"]//option[@value="0"]'), 'Select list to prioritize ' . $node_rank . ' for node ranks is visible and set to 0.');
     }
 
     // Try with sticky, then promoted. This is a test for issue
diff --git a/core/modules/shortcut/tests/src/Functional/ShortcutSetsTest.php b/core/modules/shortcut/tests/src/Functional/ShortcutSetsTest.php
index 7b4fcc76acd..b7bf4858863 100644
--- a/core/modules/shortcut/tests/src/Functional/ShortcutSetsTest.php
+++ b/core/modules/shortcut/tests/src/Functional/ShortcutSetsTest.php
@@ -64,7 +64,7 @@ class ShortcutSetsTest extends ShortcutTestBase {
 
     // Test for the table.
     $element = $this->xpath('//div[@class="layout-content"]//table');
-    $this->assertTrue($element, 'Shortcut entity list table found.');
+    $this->assertNotEmpty($element, 'Shortcut entity list table found.');
 
     // Test the table header.
     $elements = $this->xpath('//div[@class="layout-content"]//table/thead/tr/th');
diff --git a/core/modules/statistics/tests/src/Functional/StatisticsAdminTest.php b/core/modules/statistics/tests/src/Functional/StatisticsAdminTest.php
index cafdf9bbae0..b0f63344250 100644
--- a/core/modules/statistics/tests/src/Functional/StatisticsAdminTest.php
+++ b/core/modules/statistics/tests/src/Functional/StatisticsAdminTest.php
@@ -69,13 +69,13 @@ class StatisticsAdminTest extends BrowserTestBase {
    */
   public function testStatisticsSettings() {
     $config = $this->config('statistics.settings');
-    $this->assertFalse($config->get('count_content_views'), 'Count content view log is disabled by default.');
+    $this->assertEmpty($config->get('count_content_views'), 'Count content view log is disabled by default.');
 
     // Enable counter on content view.
     $edit['statistics_count_content_views'] = 1;
     $this->drupalPostForm('admin/config/system/statistics', $edit, t('Save configuration'));
     $config = $this->config('statistics.settings');
-    $this->assertTrue($config->get('count_content_views'), 'Count content view log is enabled.');
+    $this->assertNotEmpty($config->get('count_content_views'), 'Count content view log is enabled.');
 
     // Hit the node.
     $this->drupalGet('node/' . $this->testNode->id());
@@ -174,7 +174,7 @@ class StatisticsAdminTest extends BrowserTestBase {
       ->condition('nid', $this->testNode->id(), '=')
       ->execute()
       ->fetchField();
-    $this->assertFalse($result, 'Daycounter is zero.');
+    $this->assertEmpty($result, 'Daycounter is zero.');
   }
 
 }
diff --git a/core/modules/system/tests/src/Functional/Batch/ProcessingTest.php b/core/modules/system/tests/src/Functional/Batch/ProcessingTest.php
index bba551189cd..c48ff22383d 100644
--- a/core/modules/system/tests/src/Functional/Batch/ProcessingTest.php
+++ b/core/modules/system/tests/src/Functional/Batch/ProcessingTest.php
@@ -118,7 +118,7 @@ class ProcessingTest extends BrowserTestBase {
     $this->drupalGet('batch-test/multistep', ['query' => ['big_tree' => 'small_axe']]);
     $this->drupalPostForm(NULL, [], 'Submit');
     $this->assertText('step 2', 'Form is displayed in step 2.');
-    $this->assertTrue(strpos($this->getUrl(), 'batch-test/multistep?big_tree=small_axe'), 'Query argument was persisted and another extra argument was added.');
+    $this->assertContains('batch-test/multistep?big_tree=small_axe', $this->getUrl(), 'Query argument was persisted and another extra argument was added.');
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Cache/ClearTest.php b/core/modules/system/tests/src/Functional/Cache/ClearTest.php
index fe4add63886..97f424e0241 100644
--- a/core/modules/system/tests/src/Functional/Cache/ClearTest.php
+++ b/core/modules/system/tests/src/Functional/Cache/ClearTest.php
@@ -30,7 +30,7 @@ class ClearTest extends CacheTestBase {
   public function testFlushAllCaches() {
     // Create cache entries for each flushed cache bin.
     $bins = Cache::getBins();
-    $this->assertTrue($bins, 'Cache::getBins() returned bins to flush.');
+    $this->assertNotEmpty($bins, 'Cache::getBins() returned bins to flush.');
     foreach ($bins as $bin => $cache_backend) {
       $cid = 'test_cid_clear' . $bin;
       $cache_backend->set($cid, $this->defaultValue);
diff --git a/core/modules/system/tests/src/Functional/Common/UrlTest.php b/core/modules/system/tests/src/Functional/Common/UrlTest.php
index d304e122e0a..7d3eadad42a 100644
--- a/core/modules/system/tests/src/Functional/Common/UrlTest.php
+++ b/core/modules/system/tests/src/Functional/Common/UrlTest.php
@@ -212,7 +212,7 @@ class UrlTest extends BrowserTestBase {
    *   TRUE if the class is found, FALSE otherwise.
    */
   private function hasAttribute($attribute, $link, $class) {
-    return preg_match('|' . $attribute . '="([^\"\s]+\s+)*' . $class . '|', $link);
+    return (bool) preg_match('|' . $attribute . '="([^\"\s]+\s+)*' . $class . '|', $link);
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Entity/EntityCacheTagsTestBase.php b/core/modules/system/tests/src/Functional/Entity/EntityCacheTagsTestBase.php
index 2d9c5f29ec7..a5555aa157c 100644
--- a/core/modules/system/tests/src/Functional/Entity/EntityCacheTagsTestBase.php
+++ b/core/modules/system/tests/src/Functional/Entity/EntityCacheTagsTestBase.php
@@ -678,7 +678,7 @@ abstract class EntityCacheTagsTestBase extends PageCacheTagsTestBase {
   protected function verifyRenderCache($cid, array $tags, $redirected_cid = NULL) {
     // Also verify the existence of an entity render cache entry.
     $cache_entry = \Drupal::cache('render')->get($cid);
-    $this->assertTrue($cache_entry, 'A render cache entry exists.');
+    $this->assertInstanceOf(\stdClass::class, $cache_entry, 'A render cache entry exists.');
     sort($cache_entry->tags);
     sort($tags);
     $this->assertIdentical($cache_entry->tags, $tags);
diff --git a/core/modules/system/tests/src/Functional/Entity/EntityFormTest.php b/core/modules/system/tests/src/Functional/Entity/EntityFormTest.php
index f6bd340dbb1..eebe0405844 100644
--- a/core/modules/system/tests/src/Functional/Entity/EntityFormTest.php
+++ b/core/modules/system/tests/src/Functional/Entity/EntityFormTest.php
@@ -82,21 +82,21 @@ class EntityFormTest extends BrowserTestBase {
 
     $this->drupalPostForm($entity_type . '/add', $edit, t('Save'));
     $entity = $this->loadEntityByName($entity_type, $name1);
-    $this->assertTrue($entity, new FormattableMarkup('%entity_type: Entity found in the database.', ['%entity_type' => $entity_type]));
+    $this->assertNotNull($entity, new FormattableMarkup('%entity_type: Entity found in the database.', ['%entity_type' => $entity_type]));
 
     $edit['name[0][value]'] = $name2;
     $this->drupalPostForm($entity_type . '/manage/' . $entity->id() . '/edit', $edit, t('Save'));
     $entity = $this->loadEntityByName($entity_type, $name1);
-    $this->assertFalse($entity, new FormattableMarkup('%entity_type: The entity has been modified.', ['%entity_type' => $entity_type]));
+    $this->assertNull($entity, new FormattableMarkup('%entity_type: The entity has been modified.', ['%entity_type' => $entity_type]));
     $entity = $this->loadEntityByName($entity_type, $name2);
-    $this->assertTrue($entity, new FormattableMarkup('%entity_type: Modified entity found in the database.', ['%entity_type' => $entity_type]));
+    $this->assertNotNull($entity, new FormattableMarkup('%entity_type: Modified entity found in the database.', ['%entity_type' => $entity_type]));
     $this->assertNotEqual($entity->name->value, $name1, new FormattableMarkup('%entity_type: The entity name has been modified.', ['%entity_type' => $entity_type]));
 
     $this->drupalGet($entity_type . '/manage/' . $entity->id() . '/edit');
     $this->clickLink(t('Delete'));
     $this->drupalPostForm(NULL, [], t('Delete'));
     $entity = $this->loadEntityByName($entity_type, $name2);
-    $this->assertFalse($entity, new FormattableMarkup('%entity_type: Entity not found in the database.', ['%entity_type' => $entity_type]));
+    $this->assertNull($entity, new FormattableMarkup('%entity_type: Entity not found in the database.', ['%entity_type' => $entity_type]));
   }
 
   /**
@@ -117,7 +117,7 @@ class EntityFormTest extends BrowserTestBase {
 
     $this->drupalPostForm($entity_type_id . '/add', $edit, t('Save'));
     $entity = $this->loadEntityByName($entity_type_id, $name1);
-    $this->assertTrue($entity, new FormattableMarkup('%entity_type: Entity found in the database.', ['%entity_type' => $entity_type_id]));
+    $this->assertNotNull($entity, new FormattableMarkup('%entity_type: Entity found in the database.', ['%entity_type' => $entity_type_id]));
 
     // Add a translation to the newly created entity without using the Content
     // translation module.
@@ -128,7 +128,7 @@ class EntityFormTest extends BrowserTestBase {
     $edit['name[0][value]'] = $name2_ro;
     $this->drupalPostForm('ro/' . $entity_type_id . '/manage/' . $entity->id() . '/edit', $edit, t('Save'));
     $translated_entity = $this->loadEntityByName($entity_type_id, $name1)->getTranslation('ro');
-    $this->assertTrue($translated_entity, new FormattableMarkup('%entity_type: Modified translation found in the database.', ['%entity_type' => $entity_type_id]));
+    $this->assertNotNull($translated_entity, new FormattableMarkup('%entity_type: Modified translation found in the database.', ['%entity_type' => $entity_type_id]));
     $this->assertEqual($translated_entity->name->value, $name2_ro, new FormattableMarkup('%entity_type: The name of the translation has been modified.', ['%entity_type' => $entity_type_id]));
 
     $this->drupalGet('ro/' . $entity_type_id . '/manage/' . $entity->id() . '/edit');
diff --git a/core/modules/system/tests/src/Functional/Entity/EntityTranslationFormTest.php b/core/modules/system/tests/src/Functional/Entity/EntityTranslationFormTest.php
index a4472405e52..5cf93e7270d 100644
--- a/core/modules/system/tests/src/Functional/Entity/EntityTranslationFormTest.php
+++ b/core/modules/system/tests/src/Functional/Entity/EntityTranslationFormTest.php
@@ -5,6 +5,7 @@ namespace Drupal\Tests\system\Functional\Entity;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\node\Entity\Node;
 use Drupal\Tests\BrowserTestBase;
 
 /**
@@ -99,7 +100,7 @@ class EntityTranslationFormTest extends BrowserTestBase {
 
     // Check to make sure the node was created.
     $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
-    $this->assertTrue($node, 'Node found in database.');
+    $this->assertInstanceOf(Node::class, $node, 'Node found in database.');
 
     // Make body translatable.
     $field_storage = FieldStorageConfig::loadByName('node', 'body');
diff --git a/core/modules/system/tests/src/Functional/Entity/EntityViewControllerTest.php b/core/modules/system/tests/src/Functional/Entity/EntityViewControllerTest.php
index bdc63f2dbc7..b5c1db7c3fc 100644
--- a/core/modules/system/tests/src/Functional/Entity/EntityViewControllerTest.php
+++ b/core/modules/system/tests/src/Functional/Entity/EntityViewControllerTest.php
@@ -105,7 +105,7 @@ class EntityViewControllerTest extends BrowserTestBase {
     // field item HTML markup.
     $this->drupalGet('entity_test/' . $entity->id());
     $xpath = $this->xpath('//div[@data-field-item-attr="foobar"]/p[text()=:value]', [':value' => $test_value]);
-    $this->assertTrue($xpath, 'The field item attribute has been found in the rendered output of the field.');
+    $this->assertNotEmpty($xpath, 'The field item attribute has been found in the rendered output of the field.');
 
     // Enable the RDF module to ensure that two modules can add attributes to
     // the same field item.
@@ -122,7 +122,7 @@ class EntityViewControllerTest extends BrowserTestBase {
     // are rendered in the field item HTML markup.
     $this->drupalGet('entity_test/' . $entity->id());
     $xpath = $this->xpath('//div[@data-field-item-attr="foobar" and @property="schema:text"]/p[text()=:value]', [':value' => $test_value]);
-    $this->assertTrue($xpath, 'The field item attributes from both modules have been found in the rendered output of the field.');
+    $this->assertNotEmpty($xpath, 'The field item attributes from both modules have been found in the rendered output of the field.');
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Form/ElementTest.php b/core/modules/system/tests/src/Functional/Form/ElementTest.php
index 1ebd39e5351..4d256f3c03c 100644
--- a/core/modules/system/tests/src/Functional/Form/ElementTest.php
+++ b/core/modules/system/tests/src/Functional/Form/ElementTest.php
@@ -88,7 +88,7 @@ class ElementTest extends BrowserTestBase {
         ':id' => 'edit-' . $type . '-foo',
         ':class' => 'description',
       ]);
-      $this->assertTrue(count($elements), new FormattableMarkup('Custom %type option description found.', [
+      $this->assertGreaterThan(0, count($elements), new FormattableMarkup('Custom %type option description found.', [
         '%type' => $type,
       ]));
     }
@@ -188,13 +188,13 @@ class ElementTest extends BrowserTestBase {
    */
   public function testRequiredFieldsetsAndDetails() {
     $this->drupalGet('form-test/group-details');
-    $this->assertFalse($this->cssSelect('summary.form-required'));
+    $this->assertEmpty($this->cssSelect('summary.form-required'));
     $this->drupalGet('form-test/group-details/1');
-    $this->assertTrue($this->cssSelect('summary.form-required'));
+    $this->assertNotEmpty($this->cssSelect('summary.form-required'));
     $this->drupalGet('form-test/group-fieldset');
-    $this->assertFalse($this->cssSelect('span.form-required'));
+    $this->assertEmpty($this->cssSelect('span.form-required'));
     $this->drupalGet('form-test/group-fieldset/1');
-    $this->assertTrue($this->cssSelect('span.form-required'));
+    $this->assertNotEmpty($this->cssSelect('span.form-required'));
   }
 
   /**
@@ -234,7 +234,7 @@ class ElementTest extends BrowserTestBase {
    */
   public function testDetailsSummaryAttributes() {
     $this->drupalGet('form-test/group-details');
-    $this->assertTrue($this->cssSelect('summary[data-summary-attribute="test"]'));
+    $this->assertSession()->elementExists('css', 'summary[data-summary-attribute="test"]');
   }
 
 }
diff --git a/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php b/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php
index 90ded5760d2..7ea6be2fc49 100644
--- a/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php
+++ b/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php
@@ -51,7 +51,7 @@ class ElementsTableSelectTest extends BrowserTestBase {
     $this->assertSession()->pageTextNotContains('Empty text.');
 
     // Test for the absence of the Select all rows tableheader.
-    $this->assertFalse($this->xpath('//th[@class="select-all"]'));
+    $this->assertSession()->elementNotExists('xpath', '//th[@class="select-all"]');
 
     $rows = ['row1', 'row2', 'row3'];
     foreach ($rows as $row) {
@@ -132,18 +132,18 @@ class ElementsTableSelectTest extends BrowserTestBase {
   public function testAdvancedSelect() {
     // When #multiple = TRUE a Select all checkbox should be displayed by default.
     $this->drupalGet('form_test/tableselect/advanced-select/multiple-true-default');
-    $this->xpath('//th[@class="select-all"]');
+    $this->assertSession()->elementExists('xpath', '//th[@class="select-all"]');
 
     // When #js_select is set to FALSE, a "Select all" checkbox should not be displayed.
     $this->drupalGet('form_test/tableselect/advanced-select/multiple-true-no-advanced-select');
-    $this->assertFalse($this->xpath('//th[@class="select-all"]'));
+    $this->assertSession()->elementNotExists('xpath', '//th[@class="select-all"]');
 
     // A "Select all" checkbox never makes sense when #multiple = FALSE, regardless of the value of #js_select.
     $this->drupalGet('form_test/tableselect/advanced-select/multiple-false-default');
-    $this->assertFalse($this->xpath('//th[@class="select-all"]'));
+    $this->assertSession()->elementNotExists('xpath', '//th[@class="select-all"]');
 
     $this->drupalGet('form_test/tableselect/advanced-select/multiple-false-advanced-select');
-    $this->assertFalse($this->xpath('//th[@class="select-all"]'));
+    $this->assertSession()->elementNotExists('xpath', '//th[@class="select-all"]');
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Form/FormTest.php b/core/modules/system/tests/src/Functional/Form/FormTest.php
index 5458f1ef3a9..08d556dc127 100644
--- a/core/modules/system/tests/src/Functional/Form/FormTest.php
+++ b/core/modules/system/tests/src/Functional/Form/FormTest.php
@@ -134,13 +134,13 @@ class FormTest extends BrowserTestBase {
             $this->assertTrue(isset($errors[$element]), "Check empty($key) '$type' field '$element'");
             if (!empty($form_output)) {
               // Make sure the form element is marked as required.
-              $this->assertTrue(preg_match($required_marker_preg, $form_output), "Required '$type' field is marked as required");
+              $this->assertRegExp($required_marker_preg, (string) $form_output, "Required '$type' field is marked as required");
             }
           }
           else {
             if (!empty($form_output)) {
               // Make sure the form element is *not* marked as required.
-              $this->assertFalse(preg_match($required_marker_preg, $form_output), "Optional '$type' field is not marked as required");
+              $this->assertNotRegExp($required_marker_preg, (string) $form_output, "Optional '$type' field is not marked as required");
             }
             if ($type == 'select') {
               // Select elements are going to have validation errors with empty
@@ -149,7 +149,8 @@ class FormTest extends BrowserTestBase {
               $this->assertTrue((empty($errors[$element]) || strpos('field is required', (string) $errors[$element]) === FALSE), "Optional '$type' field '$element' is not treated as a required element");
             }
             else {
-              // Make sure there is *no* form error for this element.
+              // Make sure there is *no* form error for this element. We're
+              // not using assertEmpty() because the array key might not exist.
               $this->assertTrue(empty($errors[$element]), "Optional '$type' field '$element' has no errors with empty input");
             }
           }
diff --git a/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
index 0faac2821a9..a210cd37a94 100644
--- a/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
+++ b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
@@ -78,7 +78,7 @@ BROKEN;
       ->pageTextContains("The 'core' or the 'core_version_requirement' key must be present in " . $path . '/broken.info.yml');
 
     // Check that the module filter text box is available.
-    $this->assertTrue($this->xpath('//input[@name="text"]'));
+    $this->assertSession()->elementExists('xpath', '//input[@name="text"]');
   }
 
 }
diff --git a/core/modules/system/tests/src/Functional/Form/SystemConfigFormTest.php b/core/modules/system/tests/src/Functional/Form/SystemConfigFormTest.php
index e5c5e17ddb1..ca56d2e6d8a 100644
--- a/core/modules/system/tests/src/Functional/Form/SystemConfigFormTest.php
+++ b/core/modules/system/tests/src/Functional/Form/SystemConfigFormTest.php
@@ -29,7 +29,7 @@ class SystemConfigFormTest extends BrowserTestBase {
   public function testSystemConfigForm() {
     $this->drupalGet('form-test/system-config-form');
     $element = $this->xpath('//div[@id = :id]/input[contains(@class, :class)]', [':id' => 'edit-actions', ':class' => 'button--primary']);
-    $this->assertTrue($element, 'The primary action submit button was found.');
+    $this->assertNotEmpty($element, 'The primary action submit button was found.');
     $this->drupalPostForm(NULL, [], t('Save configuration'));
     $this->assertText(t('The configuration options have been saved.'));
   }
diff --git a/core/modules/system/tests/src/Functional/Mail/HtmlToTextTest.php b/core/modules/system/tests/src/Functional/Mail/HtmlToTextTest.php
index 72b1fb2dd5d..bccc4f53221 100644
--- a/core/modules/system/tests/src/Functional/Mail/HtmlToTextTest.php
+++ b/core/modules/system/tests/src/Functional/Mail/HtmlToTextTest.php
@@ -242,10 +242,7 @@ class HtmlToTextTest extends BrowserTestBase {
 EOT;
     $input = str_replace(["\r", "\n"], '', $input);
     $output = MailFormatHelper::htmlToText($input);
-    $pass = $this->assertFalse(
-      preg_match('/\][^\n]*\[/s', $output),
-      'Block-level HTML tags should force newlines'
-    );
+    $pass = $this->assertNotRegExp('/\][^\n]*\[/s', $output, 'Block-level HTML tags should force newlines');
     if (!$pass) {
       $this->verbose($this->stringToHtml($output));
     }
diff --git a/core/modules/system/tests/src/Functional/Menu/LocalTasksTest.php b/core/modules/system/tests/src/Functional/Menu/LocalTasksTest.php
index 59e9becdd5f..0e767d9fbd5 100644
--- a/core/modules/system/tests/src/Functional/Menu/LocalTasksTest.php
+++ b/core/modules/system/tests/src/Functional/Menu/LocalTasksTest.php
@@ -57,7 +57,7 @@ class LocalTasksTest extends BrowserTestBase {
     $elements = $this->xpath('//*[contains(@class, :class)]//a', [
       ':class' => $level == 0 ? 'tabs primary' : 'tabs secondary',
     ]);
-    $this->assertTrue(count($elements), 'Local tasks found.');
+    $this->assertGreaterThan(0, count($elements), 'Local tasks found.');
     foreach ($routes as $index => $route_info) {
       list($route_name, $route_parameters) = $route_info;
       $expected = Url::fromRoute($route_name, $route_parameters)->toString();
@@ -98,7 +98,7 @@ class LocalTasksTest extends BrowserTestBase {
     $elements = $this->xpath('//*[contains(@class, :class)]//a', [
       ':class' => $level == 0 ? 'tabs primary' : 'tabs secondary',
     ]);
-    $this->assertFalse(count($elements), 'Local tasks not found.');
+    $this->assertEmpty($elements, 'Local tasks not found.');
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Module/DependencyTest.php b/core/modules/system/tests/src/Functional/Module/DependencyTest.php
index 7d749f6020f..2c1530790c6 100644
--- a/core/modules/system/tests/src/Functional/Module/DependencyTest.php
+++ b/core/modules/system/tests/src/Functional/Module/DependencyTest.php
@@ -53,7 +53,7 @@ class DependencyTest extends ModuleTestBase {
 
     // Assert that the language YAML files were created.
     $storage = $this->container->get('config.storage');
-    $this->assertTrue(count($storage->listAll('language.entity.')) > 0, 'Language config entity files exist.');
+    $this->assertNotEmpty($storage->listAll('language.entity.'), 'Language config entity files exist.');
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
index 31fb1b79311..0be9688a6cb 100644
--- a/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
+++ b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
@@ -300,10 +300,10 @@ class InstallUninstallTest extends ModuleTestBase {
     $existing_updates = \Drupal::keyValue('post_update')->get('existing_updates', []);
     switch ($module) {
       case 'block':
-        $this->assertFalse(array_diff(['block_post_update_disable_blocks_with_missing_contexts'], $existing_updates));
+        $this->assertEmpty(array_diff(['block_post_update_disable_blocks_with_missing_contexts'], $existing_updates));
         break;
       case 'update_test_postupdate':
-        $this->assertFalse(array_diff(['update_test_postupdate_post_update_first', 'update_test_postupdate_post_update_second', 'update_test_postupdate_post_update_test1', 'update_test_postupdate_post_update_test0'], $existing_updates));
+        $this->assertEmpty(array_diff(['update_test_postupdate_post_update_first', 'update_test_postupdate_post_update_second', 'update_test_postupdate_post_update_test1', 'update_test_postupdate_post_update_test0'], $existing_updates));
         break;
     }
   }
@@ -321,10 +321,10 @@ class InstallUninstallTest extends ModuleTestBase {
 
     switch ($module) {
       case 'block':
-        $this->assertFalse(array_intersect(['block_post_update_disable_blocks_with_missing_contexts'], $all_update_functions), 'Asserts that no pending post update functions are available.');
+        $this->assertEmpty(array_intersect(['block_post_update_disable_blocks_with_missing_contexts'], $all_update_functions), 'Asserts that no pending post update functions are available.');
 
         $existing_updates = \Drupal::keyValue('post_update')->get('existing_updates', []);
-        $this->assertFalse(array_intersect(['block_post_update_disable_blocks_with_missing_contexts'], $existing_updates), 'Asserts that no post update functions are stored in keyvalue store.');
+        $this->assertEmpty(array_intersect(['block_post_update_disable_blocks_with_missing_contexts'], $existing_updates), 'Asserts that no post update functions are stored in keyvalue store.');
         break;
     }
   }
diff --git a/core/modules/system/tests/src/Functional/Module/ModuleTestBase.php b/core/modules/system/tests/src/Functional/Module/ModuleTestBase.php
index 88007a05b8c..1e681859b6d 100644
--- a/core/modules/system/tests/src/Functional/Module/ModuleTestBase.php
+++ b/core/modules/system/tests/src/Functional/Module/ModuleTestBase.php
@@ -44,9 +44,9 @@ abstract class ModuleTestBase extends BrowserTestBase {
     $tables = $connection->schema()->findTables($connection->prefixTables('{' . $base_table . '}') . '%');
 
     if ($count) {
-      return $this->assertTrue($tables, new FormattableMarkup('Tables matching "@base_table" found.', ['@base_table' => $base_table]));
+      return $this->assertNotEmpty($tables, new FormattableMarkup('Tables matching "@base_table" found.', ['@base_table' => $base_table]));
     }
-    return $this->assertFalse($tables, new FormattableMarkup('Tables matching "@base_table" not found.', ['@base_table' => $base_table]));
+    return $this->assertEmpty($tables, new FormattableMarkup('Tables matching "@base_table" not found.', ['@base_table' => $base_table]));
   }
 
   /**
@@ -111,7 +111,7 @@ abstract class ModuleTestBase extends BrowserTestBase {
       // schema directory.
       return;
     }
-    $this->assertTrue($all_names);
+    $this->assertNotEmpty($all_names);
 
     $module_config_dependencies = \Drupal::service('config.manager')->findConfigEntityDependents('module', [$module]);
     // Look up each default configuration object name in the active
@@ -128,7 +128,7 @@ abstract class ModuleTestBase extends BrowserTestBase {
     }
     // Verify that all configuration has been installed (which means that $names
     // is empty).
-    return $this->assertFalse($names, new FormattableMarkup('All default configuration of @module module found.', ['@module' => $module]));
+    return $this->assertEmpty($names, new FormattableMarkup('All default configuration of @module module found.', ['@module' => $module]));
   }
 
   /**
@@ -142,7 +142,7 @@ abstract class ModuleTestBase extends BrowserTestBase {
    */
   public function assertNoModuleConfig($module) {
     $names = \Drupal::configFactory()->listAll($module . '.');
-    return $this->assertFalse($names, new FormattableMarkup('No configuration found for @module module.', ['@module' => $module]));
+    return $this->assertEmpty($names, new FormattableMarkup('No configuration found for @module module.', ['@module' => $module]));
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Module/UninstallTest.php b/core/modules/system/tests/src/Functional/Module/UninstallTest.php
index c4202a4cdaf..e65fe17044e 100644
--- a/core/modules/system/tests/src/Functional/Module/UninstallTest.php
+++ b/core/modules/system/tests/src/Functional/Module/UninstallTest.php
@@ -37,7 +37,7 @@ class UninstallTest extends BrowserTestBase {
     $this->container->get('module_installer')->uninstall(['module_test']);
 
     // Are the perms defined by module_test removed?
-    $this->assertFalse(user_roles(FALSE, 'module_test perm'), 'Permissions were all removed.');
+    $this->assertEmpty(user_roles(FALSE, 'module_test perm'), 'Permissions were all removed.');
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Pager/PagerTest.php b/core/modules/system/tests/src/Functional/Pager/PagerTest.php
index 7d30b145078..4a6c9d028b8 100644
--- a/core/modules/system/tests/src/Functional/Pager/PagerTest.php
+++ b/core/modules/system/tests/src/Functional/Pager/PagerTest.php
@@ -221,7 +221,7 @@ class PagerTest extends BrowserTestBase {
    */
   protected function assertPagerItems($current_page) {
     $elements = $this->xpath('//ul[contains(@class, :class)]/li', [':class' => 'pager__items']);
-    $this->assertTrue(!empty($elements), 'Pager found.');
+    $this->assertNotEmpty($elements, 'Pager found.');
 
     // Make current page 1-based.
     $current_page++;
@@ -250,7 +250,7 @@ class PagerTest extends BrowserTestBase {
       if ($current_page == $page) {
         $this->assertClass($element, 'is-active', 'Element for current page has .is-active class.');
         $link = $element->find('css', 'a');
-        $this->assertTrue($link, 'Element for current page has link.');
+        $this->assertNotEmpty($link, 'Element for current page has link.');
         $destination = $link->getAttribute('href');
         // URL query string param is 0-indexed.
         $this->assertEqual($destination, '?page=' . ($page - 1));
@@ -259,7 +259,7 @@ class PagerTest extends BrowserTestBase {
         $this->assertNoClass($element, 'is-active', "Element for page $page has no .is-active class.");
         $this->assertClass($element, 'pager__item', "Element for page $page has .pager__item class.");
         $link = $element->find('css', 'a');
-        $this->assertTrue($link, "Link to page $page found.");
+        $this->assertNotEmpty($link, "Link to page $page found.");
         // Pager link has an attribute set in pager_test_preprocess_pager().
         $this->assertEquals('yes', $link->getAttribute('pager-test'));
         $destination = $link->getAttribute('href');
@@ -268,13 +268,13 @@ class PagerTest extends BrowserTestBase {
       unset($elements[--$page]);
     }
     // Verify that no other items remain untested.
-    $this->assertTrue(empty($elements), 'All expected items found.');
+    $this->assertEmpty($elements, 'All expected items found.');
 
     // Verify first/previous and next/last items and links.
     if (isset($first)) {
       $this->assertClass($first, 'pager__item--first', 'Element for first page has .pager__item--first class.');
       $link = $first->find('css', 'a');
-      $this->assertTrue($link, 'Link to first page found.');
+      $this->assertNotEmpty($link, 'Link to first page found.');
       $this->assertNoClass($link, 'is-active', 'Link to first page is not active.');
       $this->assertEquals('first', $link->getAttribute('pager-test'));
       $destination = $link->getAttribute('href');
@@ -283,7 +283,7 @@ class PagerTest extends BrowserTestBase {
     if (isset($previous)) {
       $this->assertClass($previous, 'pager__item--previous', 'Element for first page has .pager__item--previous class.');
       $link = $previous->find('css', 'a');
-      $this->assertTrue($link, 'Link to previous page found.');
+      $this->assertNotEmpty($link, 'Link to previous page found.');
       $this->assertNoClass($link, 'is-active', 'Link to previous page is not active.');
       $this->assertEquals('previous', $link->getAttribute('pager-test'));
       $destination = $link->getAttribute('href');
@@ -293,7 +293,7 @@ class PagerTest extends BrowserTestBase {
     if (isset($next)) {
       $this->assertClass($next, 'pager__item--next', 'Element for next page has .pager__item--next class.');
       $link = $next->find('css', 'a');
-      $this->assertTrue($link, 'Link to next page found.');
+      $this->assertNotEmpty($link, 'Link to next page found.');
       $this->assertNoClass($link, 'is-active', 'Link to next page is not active.');
       $this->assertEquals('next', $link->getAttribute('pager-test'));
       $destination = $link->getAttribute('href');
@@ -303,7 +303,7 @@ class PagerTest extends BrowserTestBase {
     if (isset($last)) {
       $link = $last->find('css', 'a');
       $this->assertClass($last, 'pager__item--last', 'Element for last page has .pager__item--last class.');
-      $this->assertTrue($link, 'Link to last page found.');
+      $this->assertNotEmpty($link, 'Link to last page found.');
       $this->assertNoClass($link, 'is-active', 'Link to last page is not active.');
       $this->assertEquals('last', $link->getAttribute('pager-test'));
       $destination = $link->getAttribute('href');
diff --git a/core/modules/system/tests/src/Functional/Session/SessionAuthenticationTest.php b/core/modules/system/tests/src/Functional/Session/SessionAuthenticationTest.php
index 702486d99e4..45b40fe4251 100644
--- a/core/modules/system/tests/src/Functional/Session/SessionAuthenticationTest.php
+++ b/core/modules/system/tests/src/Functional/Session/SessionAuthenticationTest.php
@@ -72,7 +72,7 @@ class SessionAuthenticationTest extends BrowserTestBase {
     // should no longer be logged in.
     $this->drupalGet($unprotected_url);
     $this->assertResponse(200, 'An unprotected route can be accessed without basic authentication.');
-    $this->assertFalse(json_decode($session->getPage()->getContent())->user, 'The user is no longer authenticated after visiting a page without basic authentication.');
+    $this->assertEquals(0, json_decode($session->getPage()->getContent())->user, 'The user is no longer authenticated after visiting a page without basic authentication.');
 
     // If we access the protected page again without basic authentication we
     // should get 401 Unauthorized.
diff --git a/core/modules/system/tests/src/Functional/Session/SessionHttpsTest.php b/core/modules/system/tests/src/Functional/Session/SessionHttpsTest.php
index dbdbe664cea..f5847645bc1 100644
--- a/core/modules/system/tests/src/Functional/Session/SessionHttpsTest.php
+++ b/core/modules/system/tests/src/Functional/Session/SessionHttpsTest.php
@@ -257,7 +257,7 @@ class SessionHttpsTest extends BrowserTestBase {
     $args = [
       ':sid' => Crypt::hashBase64($sid),
     ];
-    return $this->assertTrue(\Drupal::database()->query('SELECT timestamp FROM {sessions} WHERE sid = :sid', $args)->fetchField(), $assertion_text);
+    return $this->assertNotEmpty(\Drupal::database()->query('SELECT timestamp FROM {sessions} WHERE sid = :sid', $args)->fetchField(), $assertion_text);
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Session/SessionTest.php b/core/modules/system/tests/src/Functional/Session/SessionTest.php
index 7141ba45394..8092bf1209e 100644
--- a/core/modules/system/tests/src/Functional/Session/SessionTest.php
+++ b/core/modules/system/tests/src/Functional/Session/SessionTest.php
@@ -51,7 +51,7 @@ class SessionTest extends BrowserTestBase {
     // Start a new session by setting a message.
     $this->drupalGet('session-test/set-message');
     $this->assertSessionCookie(TRUE);
-    $this->assertTrue(preg_match('/HttpOnly/i', $this->drupalGetHeader('Set-Cookie', TRUE)), 'Session cookie is set as HttpOnly.');
+    $this->assertRegExp('/HttpOnly/i', $this->drupalGetHeader('Set-Cookie', TRUE), 'Session cookie is set as HttpOnly.');
 
     // Verify that the session is regenerated if a module calls exit
     // in hook_user_login().
@@ -192,16 +192,16 @@ class SessionTest extends BrowserTestBase {
     // Start a new session by setting a message.
     $this->drupalGet('session-test/set-message');
     $this->assertSessionCookie(TRUE);
-    $this->assertTrue($this->drupalGetHeader('Set-Cookie'), 'New session was started.');
+    $this->assertNotEmpty($this->drupalGetHeader('Set-Cookie'), 'New session was started.');
 
     // Display the message, during the same request the session is destroyed
     // and the session cookie is unset.
     $this->drupalGet('');
     $this->assertSessionCookie(FALSE);
     $this->assertSessionEmpty(FALSE);
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'), 'Caching was bypassed.');
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'), 'Caching was bypassed.');
     $this->assertText(t('This is a dummy message.'), 'Message was displayed.');
-    $this->assertTrue(preg_match('/SESS\w+=deleted/', $this->drupalGetHeader('Set-Cookie')), 'Session cookie was deleted.');
+    $this->assertRegExp('/SESS\w+=deleted/', $this->drupalGetHeader('Set-Cookie'), 'Session cookie was deleted.');
 
     // Verify that session was destroyed.
     $this->drupalGet('');
@@ -210,7 +210,7 @@ class SessionTest extends BrowserTestBase {
     // $this->assertSessionEmpty(TRUE);
     $this->assertNoText(t('This is a dummy message.'), 'Message was not cached.');
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT', 'Page was cached.');
-    $this->assertFalse($this->drupalGetHeader('Set-Cookie'), 'New session was not started.');
+    $this->assertNull($this->drupalGetHeader('Set-Cookie'), 'New session was not started.');
 
     // Verify that no session is created if drupal_save_session(FALSE) is called.
     $this->drupalGet('session-test/set-message-but-dont-save');
diff --git a/core/modules/system/tests/src/Functional/System/AdminTest.php b/core/modules/system/tests/src/Functional/System/AdminTest.php
index a8065195124..2face42913a 100644
--- a/core/modules/system/tests/src/Functional/System/AdminTest.php
+++ b/core/modules/system/tests/src/Functional/System/AdminTest.php
@@ -159,11 +159,11 @@ class AdminTest extends BrowserTestBase {
     $this->drupalGet('admin/compact/on');
     $this->assertResponse(200, 'A valid page is returned after turning on compact mode.');
     $this->assertUrl($frontpage_url, [], 'The user is redirected to the front page after turning on compact mode.');
-    $this->assertTrue($session->getCookie('Drupal.visitor.admin_compact_mode'), 'Compact mode turns on.');
+    $this->assertEquals('1', $session->getCookie('Drupal.visitor.admin_compact_mode'), 'Compact mode turns on.');
     $this->drupalGet('admin/compact/on');
-    $this->assertTrue($session->getCookie('Drupal.visitor.admin_compact_mode'), 'Compact mode remains on after a repeat call.');
+    $this->assertEquals('1', $session->getCookie('Drupal.visitor.admin_compact_mode'), 'Compact mode remains on after a repeat call.');
     $this->drupalGet('');
-    $this->assertTrue($session->getCookie('Drupal.visitor.admin_compact_mode'), 'Compact mode persists on new requests.');
+    $this->assertEquals('1', $session->getCookie('Drupal.visitor.admin_compact_mode'), 'Compact mode persists on new requests.');
 
     $this->drupalGet('admin/compact/off');
     $this->assertResponse(200, 'A valid page is returned after turning off compact mode.');
diff --git a/core/modules/system/tests/src/Functional/System/DateTimeTest.php b/core/modules/system/tests/src/Functional/System/DateTimeTest.php
index 0ecebb433a6..7ce8db7e064 100644
--- a/core/modules/system/tests/src/Functional/System/DateTimeTest.php
+++ b/core/modules/system/tests/src/Functional/System/DateTimeTest.php
@@ -126,7 +126,7 @@ class DateTimeTest extends BrowserTestBase {
 
     // Make sure the date does not exist in config.
     $date_format = DateFormat::load($date_format_id);
-    $this->assertFalse($date_format);
+    $this->assertNull($date_format);
 
     // Add a new date format with an existing format.
     $date_format_id = strtolower($this->randomMachineName(8));
diff --git a/core/modules/system/tests/src/Functional/System/ErrorHandlerTest.php b/core/modules/system/tests/src/Functional/System/ErrorHandlerTest.php
index 5b4a7d17486..f93468b65fd 100644
--- a/core/modules/system/tests/src/Functional/System/ErrorHandlerTest.php
+++ b/core/modules/system/tests/src/Functional/System/ErrorHandlerTest.php
@@ -141,7 +141,7 @@ class ErrorHandlerTest extends BrowserTestBase {
       ->save();
 
     $this->drupalGet('error-test/trigger-exception');
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
     $this->assertIdentical(strpos($this->drupalGetHeader('Cache-Control'), 'public'), FALSE, 'Received expected HTTP status line.');
     $this->assertSession()->statusCodeEquals(500);
     $this->assertNoErrorMessage($error_exception);
@@ -170,7 +170,7 @@ class ErrorHandlerTest extends BrowserTestBase {
    *   TRUE, if there are no messages.
    */
   protected function assertNoMessages() {
-    return $this->assertFalse($this->xpath('//div[contains(@class, "messages")]'), 'Ensures that also no messages div exists, which proves that no messages were generated by the error handler, not even an empty one.');
+    return $this->assertEmpty($this->xpath('//div[contains(@class, "messages")]'), 'Ensures that also no messages div exists, which proves that no messages were generated by the error handler, not even an empty one.');
   }
 
 }
diff --git a/core/modules/system/tests/src/Functional/Theme/TwigTransTest.php b/core/modules/system/tests/src/Functional/Theme/TwigTransTest.php
index eddd5280326..9b93eb1d93b 100644
--- a/core/modules/system/tests/src/Functional/Theme/TwigTransTest.php
+++ b/core/modules/system/tests/src/Functional/Theme/TwigTransTest.php
@@ -113,7 +113,7 @@ class TwigTransTest extends BrowserTestBase {
       $this->fail('{% trans %}{% endtrans %} did not throw an exception.');
     }
     catch (\Twig_Error_Syntax $e) {
-      $this->assertTrue(strstr($e->getMessage(), '{% trans %} tag cannot be empty'), '{% trans %}{% endtrans %} threw the expected exception.');
+      $this->assertContains('{% trans %} tag cannot be empty', $e->getMessage(), '{% trans %}{% endtrans %} threw the expected exception.');
     }
     catch (\Exception $e) {
       $this->fail('{% trans %}{% endtrans %} threw an unexpected exception.');
diff --git a/core/modules/system/tests/src/Functional/Update/EntityUpdateAddRevisionTranslationAffectedTest.php b/core/modules/system/tests/src/Functional/Update/EntityUpdateAddRevisionTranslationAffectedTest.php
index 2c5fccb048b..6e0d9985c32 100644
--- a/core/modules/system/tests/src/Functional/Update/EntityUpdateAddRevisionTranslationAffectedTest.php
+++ b/core/modules/system/tests/src/Functional/Update/EntityUpdateAddRevisionTranslationAffectedTest.php
@@ -84,7 +84,7 @@ class EntityUpdateAddRevisionTranslationAffectedTest extends UpdatePathTestBase
     // Check that the correct initial value was set when the field was
     // installed.
     $entity = \Drupal::entityTypeManager()->getStorage('entity_test_update')->load(1);
-    $this->assertTrue($entity->revision_translation_affected->value);
+    $this->assertNotEmpty($entity->revision_translation_affected->value);
   }
 
   /**
diff --git a/core/modules/system/tests/src/Functional/Update/InstallProfileSystemInstall8300Test.php b/core/modules/system/tests/src/Functional/Update/InstallProfileSystemInstall8300Test.php
index ced5847bc6d..9d3131ff9e7 100644
--- a/core/modules/system/tests/src/Functional/Update/InstallProfileSystemInstall8300Test.php
+++ b/core/modules/system/tests/src/Functional/Update/InstallProfileSystemInstall8300Test.php
@@ -37,7 +37,7 @@ class InstallProfileSystemInstall8300Test extends UpdatePathTestBase {
     // expected state before updating.
     $this->assertEqual('standard', \Drupal::installProfile());
     $this->assertEqual('standard', Settings::get('install_profile'), 'The install profile has not been written to settings.php.');
-    $this->assertFalse($this->config('core.extension')->get('profile'), 'The install profile is not present in core.extension configuration.');
+    $this->assertNull($this->config('core.extension')->get('profile'), 'The install profile is not present in core.extension configuration.');
 
     $this->runUpdates();
     // Confirm that Drupal recognizes this distribution as the current profile.
diff --git a/core/modules/system/tests/src/Functional/Update/LocalActionsAndTasksConvertedIntoBlocksUpdateTest.php b/core/modules/system/tests/src/Functional/Update/LocalActionsAndTasksConvertedIntoBlocksUpdateTest.php
index b343d7ac04b..5b4e1bbd967 100644
--- a/core/modules/system/tests/src/Functional/Update/LocalActionsAndTasksConvertedIntoBlocksUpdateTest.php
+++ b/core/modules/system/tests/src/Functional/Update/LocalActionsAndTasksConvertedIntoBlocksUpdateTest.php
@@ -80,7 +80,7 @@ class LocalActionsAndTasksConvertedIntoBlocksUpdateTest extends UpdatePathTestBa
     // Local actions are visible on the content listing page.
     $this->drupalGet('admin/content');
     $action_link = $this->cssSelect('.action-links');
-    $this->assertTrue($action_link);
+    $this->assertNotEmpty($action_link);
 
     $this->drupalGet('admin/structure/block/list/seven');
 
diff --git a/core/modules/system/tests/src/Functional/Update/RebuildScriptTest.php b/core/modules/system/tests/src/Functional/Update/RebuildScriptTest.php
index d47e9771a4a..da036ad6e62 100644
--- a/core/modules/system/tests/src/Functional/Update/RebuildScriptTest.php
+++ b/core/modules/system/tests/src/Functional/Update/RebuildScriptTest.php
@@ -26,7 +26,7 @@ class RebuildScriptTest extends BrowserTestBase {
     $cache->set('rebuild_test', TRUE);
     $this->drupalGet(Url::fromUri('base:core/rebuild.php'));
     $this->assertUrl(new Url('<front>'));
-    $this->assertTrue($cache->get('rebuild_test'));
+    $this->assertInstanceOf(\stdClass::class, $cache->get('rebuild_test'));
 
     $settings['settings']['rebuild_access'] = (object) [
       'value' => TRUE,
diff --git a/core/modules/system/tests/src/Functional/Update/SevenSecondaryLocalTasksConvertedIntoBlockUpdateTest.php b/core/modules/system/tests/src/Functional/Update/SevenSecondaryLocalTasksConvertedIntoBlockUpdateTest.php
index f0427d31a2f..a5637564b88 100644
--- a/core/modules/system/tests/src/Functional/Update/SevenSecondaryLocalTasksConvertedIntoBlockUpdateTest.php
+++ b/core/modules/system/tests/src/Functional/Update/SevenSecondaryLocalTasksConvertedIntoBlockUpdateTest.php
@@ -59,7 +59,7 @@ class SevenSecondaryLocalTasksConvertedIntoBlockUpdateTest extends UpdatePathTes
     // Local actions are visible on the content listing page.
     $this->drupalGet('admin/structure/block');
     $action_link = $this->cssSelect('#secondary-tabs-title');
-    $this->assertTrue($action_link);
+    $this->assertNotEmpty($action_link);
   }
 
 }
diff --git a/core/modules/system/tests/src/Functional/Update/UpdateScriptTest.php b/core/modules/system/tests/src/Functional/Update/UpdateScriptTest.php
index 189a1494573..3e484f231f0 100644
--- a/core/modules/system/tests/src/Functional/Update/UpdateScriptTest.php
+++ b/core/modules/system/tests/src/Functional/Update/UpdateScriptTest.php
@@ -213,7 +213,7 @@ class UpdateScriptTest extends BrowserTestBase {
    */
   public function testSuccessfulUpdateFunctionality() {
     $initial_maintenance_mode = $this->container->get('state')->get('system.maintenance_mode');
-    $this->assertFalse($initial_maintenance_mode, 'Site is not in maintenance mode.');
+    $this->assertNull($initial_maintenance_mode, 'Site is not in maintenance mode.');
     $this->runUpdates($initial_maintenance_mode);
     $final_maintenance_mode = $this->container->get('state')->get('system.maintenance_mode');
     $this->assertEqual($final_maintenance_mode, $initial_maintenance_mode, 'Maintenance mode should not have changed after database updates.');
diff --git a/core/modules/system/tests/src/Kernel/Migrate/d7/MigrateThemeSettingsTest.php b/core/modules/system/tests/src/Kernel/Migrate/d7/MigrateThemeSettingsTest.php
index ba4747c8c04..333795e767d 100644
--- a/core/modules/system/tests/src/Kernel/Migrate/d7/MigrateThemeSettingsTest.php
+++ b/core/modules/system/tests/src/Kernel/Migrate/d7/MigrateThemeSettingsTest.php
@@ -34,7 +34,7 @@ class MigrateThemeSettingsTest extends MigrateDrupal7TestBase {
     $this->assertTrue($config->get('features.comment_user_verification'));
     $this->assertTrue($config->get('features.favicon'));
     $this->assertTrue($config->get('features.node_user_picture'));
-    $this->assertFalse($config->get('features.logo'));
+    $this->assertNull($config->get('features.logo'));
     $this->assertTrue($config->get('features.name'));
     $this->assertTrue($config->get('features.slogan'));
     $this->assertSame('public://gnu.png', $config->get('logo.path'));
@@ -47,7 +47,7 @@ class MigrateThemeSettingsTest extends MigrateDrupal7TestBase {
     $this->assertTrue($config->get('features.comment_user_verification'));
     $this->assertTrue($config->get('features.favicon'));
     $this->assertTrue($config->get('features.node_user_picture'));
-    $this->assertFalse($config->get('features.logo'));
+    $this->assertNull($config->get('features.logo'));
     $this->assertTrue($config->get('features.name'));
     $this->assertTrue($config->get('features.slogan'));
     $this->assertSame('', $config->get('logo.path'));
diff --git a/core/modules/system/tests/src/Kernel/System/CronQueueTest.php b/core/modules/system/tests/src/Kernel/System/CronQueueTest.php
index 649a2c75265..81f03758980 100644
--- a/core/modules/system/tests/src/Kernel/System/CronQueueTest.php
+++ b/core/modules/system/tests/src/Kernel/System/CronQueueTest.php
@@ -105,8 +105,8 @@ class CronQueueTest extends KernelTestBase {
     $queue->createItem([]);
     $this->cron->run();
 
-    $this->assertEqual(\Drupal::state()->get('cron_queue_test_requeue_exception'), 2);
-    $this->assertFalse($queue->numberOfItems());
+    $this->assertEquals(2, \Drupal::state()->get('cron_queue_test_requeue_exception'));
+    $this->assertEquals(0, $queue->numberOfItems());
   }
 
 }
diff --git a/core/modules/taxonomy/tests/src/Functional/LoadMultipleTest.php b/core/modules/taxonomy/tests/src/Functional/LoadMultipleTest.php
index 5a05fe6363b..9dadd3391f8 100644
--- a/core/modules/taxonomy/tests/src/Functional/LoadMultipleTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/LoadMultipleTest.php
@@ -51,7 +51,7 @@ class LoadMultipleTest extends TaxonomyTestBase {
     $deleted = array_shift($terms2);
     $deleted->delete();
     $deleted_term = Term::load($deleted->id());
-    $this->assertFalse($deleted_term);
+    $this->assertNull($deleted_term);
 
     // Load terms from the vocabulary by vid.
     $terms3 = $term_storage->loadByProperties(['vid' => $vocabulary->id()]);
diff --git a/core/modules/taxonomy/tests/src/Functional/TermTest.php b/core/modules/taxonomy/tests/src/Functional/TermTest.php
index a15a44da66b..18fae67ba21 100644
--- a/core/modules/taxonomy/tests/src/Functional/TermTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/TermTest.php
@@ -367,12 +367,12 @@ class TermTest extends TaxonomyTestBase {
     $this->assertText($edit['description[0][value]'], 'The randomly generated term description is present.');
 
     // Did this page request display a 'term-listing-heading'?
-    $this->assertTrue($this->xpath('//div[contains(@class, "field--name-description")]'), 'Term page displayed the term description element.');
+    $this->assertSession()->elementExists('xpath', '//div[contains(@class, "field--name-description")]');
     // Check that it does NOT show a description when description is blank.
     $term->setDescription(NULL);
     $term->save();
     $this->drupalGet('taxonomy/term/' . $term->id());
-    $this->assertFalse($this->xpath('//div[contains(@class, "field--entity-taxonomy-term--description")]'), 'Term page did not display the term description when description was blank.');
+    $this->assertSession()->elementNotExists('xpath', '//div[contains(@class, "field--entity-taxonomy-term--description")]');
 
     // Check that the description value is processed.
     $value = $this->randomMachineName();
@@ -513,11 +513,11 @@ class TermTest extends TaxonomyTestBase {
 
     // Try to load an invalid term name.
     $terms = taxonomy_term_load_multiple_by_name('Banana');
-    $this->assertFalse($terms, 'No term loaded with an invalid name.');
+    $this->assertEmpty($terms, 'No term loaded with an invalid name.');
 
     // Try to load the term using a substring of the name.
     $terms = taxonomy_term_load_multiple_by_name(mb_substr($term->getName(), 2), 'No term loaded with a substring of the name.');
-    $this->assertFalse($terms);
+    $this->assertEmpty($terms);
 
     // Create a new term in a different vocabulary with the same name.
     $new_vocabulary = $this->createVocabulary();
@@ -542,7 +542,7 @@ class TermTest extends TaxonomyTestBase {
     // Try to load a term by name that doesn't exist in this vocabulary but
     // exists in another vocabulary.
     $terms = taxonomy_term_load_multiple_by_name($term2->getName(), $new_vocabulary->id());
-    $this->assertFalse($terms, 'Invalid term name restricted by vocabulary machine name not loaded.');
+    $this->assertEmpty($terms, 'Invalid term name restricted by vocabulary machine name not loaded.');
 
     // Try to load terms filtering by a non-existing vocabulary.
     $terms = taxonomy_term_load_multiple_by_name($term2->getName(), 'non_existing_vocabulary');
diff --git a/core/modules/taxonomy/tests/src/Functional/VocabularyUiTest.php b/core/modules/taxonomy/tests/src/Functional/VocabularyUiTest.php
index 1a738958dbf..7419930a51f 100644
--- a/core/modules/taxonomy/tests/src/Functional/VocabularyUiTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/VocabularyUiTest.php
@@ -123,7 +123,7 @@ class VocabularyUiTest extends TaxonomyTestBase {
       $vocabulary->delete();
     }
     // Confirm that no vocabularies are found in the database.
-    $this->assertFalse(Vocabulary::loadMultiple(), 'No vocabularies found.');
+    $this->assertEmpty(Vocabulary::loadMultiple(), 'No vocabularies found.');
     $this->drupalGet('admin/structure/taxonomy');
     // Check the default message for no vocabularies.
     $this->assertText(t('No vocabularies available.'));
@@ -145,7 +145,7 @@ class VocabularyUiTest extends TaxonomyTestBase {
     // Check the created vocabulary.
     $this->container->get('entity_type.manager')->getStorage('taxonomy_vocabulary')->resetCache();
     $vocabulary = Vocabulary::load($vid);
-    $this->assertTrue($vocabulary, 'Vocabulary found.');
+    $this->assertNotEmpty($vocabulary, 'Vocabulary found.');
 
     // Delete the vocabulary.
     $this->drupalGet('admin/structure/taxonomy/manage/' . $vocabulary->id());
@@ -157,7 +157,7 @@ class VocabularyUiTest extends TaxonomyTestBase {
     $this->drupalPostForm(NULL, NULL, t('Delete'));
     $this->assertRaw(t('Deleted vocabulary %name.', ['%name' => $vocabulary->label()]), 'Vocabulary deleted.');
     $this->container->get('entity_type.manager')->getStorage('taxonomy_vocabulary')->resetCache();
-    $this->assertFalse(Vocabulary::load($vid), 'Vocabulary not found.');
+    $this->assertNull(Vocabulary::load($vid), 'Vocabulary not found.');
   }
 
 }
diff --git a/core/modules/taxonomy/tests/src/Kernel/Migrate/MigrateTaxonomyTermStubTest.php b/core/modules/taxonomy/tests/src/Kernel/Migrate/MigrateTaxonomyTermStubTest.php
index 2da51e4a439..d601a4b0657 100644
--- a/core/modules/taxonomy/tests/src/Kernel/Migrate/MigrateTaxonomyTermStubTest.php
+++ b/core/modules/taxonomy/tests/src/Kernel/Migrate/MigrateTaxonomyTermStubTest.php
@@ -72,12 +72,12 @@ class MigrateTaxonomyTermStubTest extends MigrateDrupalTestBase {
     $migration = $this->getMigration('taxonomy_term_stub_test');
     $term_executable = new MigrateExecutable($migration, $this);
     $term_executable->import();
-    $this->assertTrue($migration->getIdMap()->getRowBySource(['2']), 'Stub row exists in the ID map table');
+    $this->assertNotEmpty($migration->getIdMap()->getRowBySource(['2']), 'Stub row exists in the ID map table');
 
     // Load the referenced term, which should exist as a stub.
     /** @var \Drupal\Core\Entity\ContentEntityBase $stub_entity */
     $stub_entity = Term::load(2);
-    $this->assertTrue($stub_entity, 'Stub successfully created');
+    $this->assertNotEmpty($stub_entity, 'Stub successfully created');
     if ($stub_entity) {
       $this->assertIdentical(count($stub_entity->validate()), 0, 'Stub is a valid entity');
     }
diff --git a/core/modules/toolbar/tests/src/Functional/ToolbarAdminMenuTest.php b/core/modules/toolbar/tests/src/Functional/ToolbarAdminMenuTest.php
index 7260d239579..f7e9955ecf8 100644
--- a/core/modules/toolbar/tests/src/Functional/ToolbarAdminMenuTest.php
+++ b/core/modules/toolbar/tests/src/Functional/ToolbarAdminMenuTest.php
@@ -206,7 +206,7 @@ class ToolbarAdminMenuTest extends BrowserTestBase {
 
     // Assert that the old admin menu subtree hash and the new admin menu
     // subtree hash are the same.
-    $this->assertTrue($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
+    $this->assertNotEmpty($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
     $this->assertEqual($admin_user_2_hash, $new_subtree_hash, 'The user-specific subtree menu hash has not been updated.');
   }
 
@@ -242,7 +242,7 @@ class ToolbarAdminMenuTest extends BrowserTestBase {
 
     // Assert that the old adminUser subtree hash and the new adminUser
     // subtree hash are the same.
-    $this->assertTrue($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
+    $this->assertNotEmpty($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
     $this->assertEqual($admin_user_2_hash, $new_subtree_hash, 'The user-specific subtree menu hash has not been updated.');
   }
 
@@ -283,7 +283,7 @@ class ToolbarAdminMenuTest extends BrowserTestBase {
     // Get a baseline hash for the admin menu subtrees before translating one
     // of the menu link items.
     $original_subtree_hash = $this->getSubtreesHash();
-    $this->assertTrue($original_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
+    $this->assertNotEmpty($original_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
     $this->drupalLogout();
 
     // Translate the string 'Search and metadata' in the xx language. This
@@ -323,7 +323,7 @@ class ToolbarAdminMenuTest extends BrowserTestBase {
 
     // Assert that the old admin menu subtrees hash and the new admin menu
     // subtrees hash are different.
-    $this->assertTrue($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
+    $this->assertNotEmpty($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
     $this->assertNotEqual($original_subtree_hash, $new_subtree_hash, 'The user-specific subtree menu hash has been updated.');
   }
 
@@ -362,7 +362,7 @@ class ToolbarAdminMenuTest extends BrowserTestBase {
 
     // Assert that the old admin menu subtree hash and the new admin menu
     // subtree hash are different.
-    $this->assertTrue($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
+    $this->assertNotEmpty($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
     $this->assertNotEqual($this->hash, $new_subtree_hash, 'The user-specific subtree menu hash has been updated.');
   }
 
@@ -373,7 +373,7 @@ class ToolbarAdminMenuTest extends BrowserTestBase {
     // Back to site link should exist in the markup.
     $this->drupalGet('test-page');
     $back_link = $this->cssSelect('.home-toolbar-tab');
-    $this->assertTrue($back_link);
+    $this->assertNotEmpty($back_link);
   }
 
   /**
@@ -425,7 +425,7 @@ class ToolbarAdminMenuTest extends BrowserTestBase {
 
     // Assert that the old admin menu subtree hash and the new admin menu
     // subtree hash are different.
-    $this->assertTrue($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
+    $this->assertNotEmpty($new_subtree_hash, 'A valid hash value for the admin menu subtrees was created.');
     $this->assertNotEqual($this->hash, $new_subtree_hash, 'The user-specific subtree menu hash has been updated.');
 
     // Save the new subtree hash as the original.
diff --git a/core/modules/user/tests/src/Functional/Update/UserUpdateEmailToken.php b/core/modules/user/tests/src/Functional/Update/UserUpdateEmailToken.php
index 80360c17388..4e4b9f62818 100644
--- a/core/modules/user/tests/src/Functional/Update/UserUpdateEmailToken.php
+++ b/core/modules/user/tests/src/Functional/Update/UserUpdateEmailToken.php
@@ -27,10 +27,10 @@ class UserUpdateEmailToken extends UpdatePathTestBase {
    */
   public function testEmailToken() {
     $mail = \Drupal::config('user.mail')->get('status_blocked');
-    $this->assertTrue(strpos($mail['body'], '[site:account-name]'));
+    $this->assertContains('[site:account-name]', $mail['body']);
     $this->runUpdates();
     $mail = \Drupal::config('user.mail')->get('status_blocked');
-    $this->assertFalse(strpos($mail['body'], '[site:account-name]'));
+    $this->assertNotContains('[site:account-name]', $mail['body']);
   }
 
 }
diff --git a/core/modules/user/tests/src/Functional/UserAdminListingTest.php b/core/modules/user/tests/src/Functional/UserAdminListingTest.php
index ec4375a143b..c34e0aae8c9 100644
--- a/core/modules/user/tests/src/Functional/UserAdminListingTest.php
+++ b/core/modules/user/tests/src/Functional/UserAdminListingTest.php
@@ -87,7 +87,7 @@ class UserAdminListingTest extends BrowserTestBase {
       ];
     }
 
-    $this->assertFalse(array_keys(array_diff_key($result_accounts, $accounts)), 'Ensure all accounts are listed.');
+    $this->assertEmpty(array_keys(array_diff_key($result_accounts, $accounts)), 'Ensure all accounts are listed.');
     foreach ($result_accounts as $name => $values) {
       $this->assertEqual($values['status'] == t('active'), $accounts[$name]->status->value, 'Ensure the status is displayed properly.');
     }
diff --git a/core/modules/user/tests/src/Functional/UserAdminTest.php b/core/modules/user/tests/src/Functional/UserAdminTest.php
index 991f99304d6..f0a59ed7bee 100644
--- a/core/modules/user/tests/src/Functional/UserAdminTest.php
+++ b/core/modules/user/tests/src/Functional/UserAdminTest.php
@@ -196,7 +196,7 @@ class UserAdminTest extends BrowserTestBase {
       'from' => $server_address,
       'subject' => $subject,
     ]);
-    $this->assertTrue(count($admin_mail), 'New user mail to admin is sent to configured Notification Email address');
+    $this->assertCount(1, $admin_mail, 'New user mail to admin is sent to configured Notification Email address');
     // Ensure that user notification mail is sent from the configured
     // Notification Email address.
     $user_mail = $this->drupalGetMails([
@@ -205,7 +205,7 @@ class UserAdminTest extends BrowserTestBase {
       'reply-to' => $notify_address,
       'subject' => $subject,
     ]);
-    $this->assertTrue(count($user_mail), 'New user mail to user is sent from configured Notification Email address');
+    $this->assertCount(1, $user_mail, 'New user mail to user is sent from configured Notification Email address');
   }
 
 }
diff --git a/core/modules/user/tests/src/Functional/UserCancelTest.php b/core/modules/user/tests/src/Functional/UserCancelTest.php
index 65632c03a0b..1d8e40c752b 100644
--- a/core/modules/user/tests/src/Functional/UserCancelTest.php
+++ b/core/modules/user/tests/src/Functional/UserCancelTest.php
@@ -5,6 +5,7 @@ namespace Drupal\Tests\user\Functional;
 use Drupal\comment\CommentInterface;
 use Drupal\comment\Entity\Comment;
 use Drupal\comment\Tests\CommentTestTrait;
+use Drupal\node\Entity\Node;
 use Drupal\Tests\BrowserTestBase;
 use Drupal\user\Entity\User;
 
@@ -90,7 +91,7 @@ class UserCancelTest extends BrowserTestBase {
 
     // Confirm deletion.
     $this->assertRaw(t('%name has been deleted.', ['%name' => $account->getAccountName()]), 'User deleted.');
-    $this->assertFalse(User::load($account->id()), 'User is not found in the database.');
+    $this->assertNull(User::load($account->id()), 'User is not found in the database.');
   }
 
   /**
@@ -337,7 +338,7 @@ class UserCancelTest extends BrowserTestBase {
     // Confirm account cancellation request.
     $this->drupalGet("user/" . $account->id() . "/cancel/confirm/$timestamp/" . user_pass_rehash($account, $timestamp));
     $user_storage->resetCache([$account->id()]);
-    $this->assertFalse($user_storage->load($account->id()), 'User is not found in the database.');
+    $this->assertNull($user_storage->load($account->id()), 'User is not found in the database.');
 
     // Confirm that user's content has been attributed to anonymous user.
     $anonymous_user = User::getAnonymousUser();
@@ -397,7 +398,7 @@ class UserCancelTest extends BrowserTestBase {
     // Confirm account cancellation request.
     $this->drupalGet("user/" . $account->id() . "/cancel/confirm/$timestamp/" . user_pass_rehash($account, $timestamp));
     $user_storage->resetCache([$account->id()]);
-    $this->assertFalse($user_storage->load($account->id()), 'User is not found in the database.');
+    $this->assertNull($user_storage->load($account->id()), 'User is not found in the database.');
 
     // Confirm that user's content has been attributed to anonymous user.
     $node_storage->resetCache(array_keys($nodes));
@@ -438,7 +439,7 @@ class UserCancelTest extends BrowserTestBase {
     $this->assertText(t('Your comment has been posted.'));
     $comments = \Drupal::entityTypeManager()->getStorage('comment')->loadByProperties(['subject' => $edit['subject[0][value]']]);
     $comment = reset($comments);
-    $this->assertTrue($comment->id(), 'Comment found.');
+    $this->assertNotEmpty($comment->id(), 'Comment found.');
 
     // Create a node with two revisions, the initial one belonging to the
     // cancelling user.
@@ -464,16 +465,16 @@ class UserCancelTest extends BrowserTestBase {
     // Confirm account cancellation request.
     $this->drupalGet("user/" . $account->id() . "/cancel/confirm/$timestamp/" . user_pass_rehash($account, $timestamp));
     $user_storage->resetCache([$account->id()]);
-    $this->assertFalse($user_storage->load($account->id()), 'User is not found in the database.');
+    $this->assertNull($user_storage->load($account->id()), 'User is not found in the database.');
 
     // Confirm that user's content has been deleted.
     $node_storage->resetCache([$node->id()]);
-    $this->assertFalse($node_storage->load($node->id()), 'Node of the user has been deleted.');
-    $this->assertFalse(node_revision_load($revision), 'Node revision of the user has been deleted.');
+    $this->assertNull($node_storage->load($node->id()), 'Node of the user has been deleted.');
+    $this->assertNull(node_revision_load($revision), 'Node revision of the user has been deleted.');
     $node_storage->resetCache([$revision_node->id()]);
-    $this->assertTrue($node_storage->load($revision_node->id()), "Current revision of the user's node was not deleted.");
+    $this->assertInstanceOf(Node::class, $node_storage->load($revision_node->id()), "Current revision of the user's node was not deleted.");
     \Drupal::entityTypeManager()->getStorage('comment')->resetCache([$comment->id()]);
-    $this->assertFalse(Comment::load($comment->id()), 'Comment of the user has been deleted.');
+    $this->assertNull(Comment::load($comment->id()), 'Comment of the user has been deleted.');
 
     // Confirm that the confirmation message made it through to the end user.
     $this->assertRaw(t('%name has been deleted.', ['%name' => $account->getAccountName()]), "Confirmation message displayed to user.");
@@ -501,7 +502,7 @@ class UserCancelTest extends BrowserTestBase {
     // Confirm deletion.
     $this->drupalPostForm(NULL, NULL, t('Cancel account'));
     $this->assertRaw(t('%name has been deleted.', ['%name' => $account->getAccountName()]), 'User deleted.');
-    $this->assertFalse(User::load($account->id()), 'User is not found in the database.');
+    $this->assertNull(User::load($account->id()), 'User is not found in the database.');
   }
 
   /**
@@ -529,7 +530,7 @@ class UserCancelTest extends BrowserTestBase {
     // Confirm deletion.
     $this->drupalPostForm(NULL, NULL, t('Cancel account'));
     $this->assertRaw(t('%name has been deleted.', ['%name' => $account->getAccountName()]), 'User deleted.');
-    $this->assertFalse(User::load($account->id()), 'User is not found in the database.');
+    $this->assertNull(User::load($account->id()), 'User is not found in the database.');
   }
 
   /**
diff --git a/core/modules/user/tests/src/Functional/UserPasswordResetTest.php b/core/modules/user/tests/src/Functional/UserPasswordResetTest.php
index 650c2dfd01a..f6033a8e1e5 100644
--- a/core/modules/user/tests/src/Functional/UserPasswordResetTest.php
+++ b/core/modules/user/tests/src/Functional/UserPasswordResetTest.php
@@ -92,11 +92,11 @@ class UserPasswordResetTest extends PageCacheTagsTestBase {
     // Ensure that the current url does not contain the hash and timestamp.
     $this->assertUrl(Url::fromRoute('user.reset.form', ['uid' => $this->account->id()]));
 
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Ensure the password reset URL is not cached.
     $this->drupalGet($resetURL);
-    $this->assertFalse($this->drupalGetHeader('X-Drupal-Cache'));
+    $this->assertNull($this->drupalGetHeader('X-Drupal-Cache'));
 
     // Check the one-time login page.
     $this->assertText($this->account->getAccountName(), 'One-time login page contains the correct username.');
diff --git a/core/modules/user/tests/src/Functional/UserPictureTest.php b/core/modules/user/tests/src/Functional/UserPictureTest.php
index efb785d6259..9aa5e45ae4c 100644
--- a/core/modules/user/tests/src/Functional/UserPictureTest.php
+++ b/core/modules/user/tests/src/Functional/UserPictureTest.php
@@ -91,7 +91,7 @@ class UserPictureTest extends BrowserTestBase {
     \Drupal::service('cron')->run();
 
     // Verify that the image has been deleted.
-    $this->assertFalse(File::load($file->id()), 'File was removed from the database.');
+    $this->assertNull(File::load($file->id()), 'File was removed from the database.');
     // Clear out PHP's file stat cache so we see the current value.
     clearstatcache(TRUE, $file->getFileUri());
     $this->assertFalse(is_file($file->getFileUri()), 'File was removed from the file system.');
diff --git a/core/modules/user/tests/src/Functional/UserRegistrationTest.php b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
index b72d7ec776f..760836b307e 100644
--- a/core/modules/user/tests/src/Functional/UserRegistrationTest.php
+++ b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
@@ -215,7 +215,7 @@ class UserRegistrationTest extends BrowserTestBase {
 
     $user_storage = \Drupal::entityTypeManager()->getStorage('user');
 
-    $this->assertTrue($user_storage->loadByProperties(['name' => $edit['name']]));
+    $this->assertNotEmpty($user_storage->loadByProperties(['name' => $edit['name']]));
     $this->drupalLogout();
 
     // Create a second account.
@@ -226,7 +226,7 @@ class UserRegistrationTest extends BrowserTestBase {
     $this->drupalPostForm('user/register', $edit, t('Create new account'));
     $this->assertResponse(200);
 
-    $this->assertTrue($user_storage->loadByProperties(['name' => $edit['name']]));
+    $this->assertNotEmpty($user_storage->loadByProperties(['name' => $edit['name']]));
   }
 
   public function testRegistrationDefaultValues() {
diff --git a/core/modules/user/tests/src/Functional/UserRoleAdminTest.php b/core/modules/user/tests/src/Functional/UserRoleAdminTest.php
index ff529f83feb..1596484b813 100644
--- a/core/modules/user/tests/src/Functional/UserRoleAdminTest.php
+++ b/core/modules/user/tests/src/Functional/UserRoleAdminTest.php
@@ -88,7 +88,7 @@ class UserRoleAdminTest extends BrowserTestBase {
     $this->assertRaw(t('The role %label has been deleted.', ['%label' => $role_name]));
     $this->assertNoLinkByHref("admin/people/roles/manage/{$role->id()}", 'Role edit link removed.');
     \Drupal::entityTypeManager()->getStorage('user_role')->resetCache([$role->id()]);
-    $this->assertFalse(Role::load($role->id()), 'A deleted role can no longer be loaded.');
+    $this->assertNull(Role::load($role->id()), 'A deleted role can no longer be loaded.');
 
     // Make sure that the system-defined roles can be edited via the user
     // interface.
diff --git a/core/modules/user/tests/src/Kernel/ContextProvider/CurrentUserContextTest.php b/core/modules/user/tests/src/Kernel/ContextProvider/CurrentUserContextTest.php
index be9e829e4eb..e4460cd91a7 100644
--- a/core/modules/user/tests/src/Kernel/ContextProvider/CurrentUserContextTest.php
+++ b/core/modules/user/tests/src/Kernel/ContextProvider/CurrentUserContextTest.php
@@ -46,7 +46,7 @@ class CurrentUserContextTest extends KernelTestBase {
     $this->assertArrayHasKey('@user.current_user_context:current_user', $contexts);
     $this->assertSame('entity:user', $contexts['@user.current_user_context:current_user']->getContextDefinition()->getDataType());
     $this->assertTrue($contexts['@user.current_user_context:current_user']->hasContextValue());
-    $this->assertTrue($contexts['@user.current_user_context:current_user']->getContextValue());
+    $this->assertNotNull($contexts['@user.current_user_context:current_user']->getContextValue());
 
     // Test an anonymous account.
     $anonymous = $this->prophesize(AccountInterface::class);
diff --git a/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserPictureFileTest.php b/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserPictureFileTest.php
index 1d28e2a7dc1..eb9e299d664 100644
--- a/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserPictureFileTest.php
+++ b/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserPictureFileTest.php
@@ -46,7 +46,7 @@ class MigrateUserPictureFileTest extends MigrateDrupal6TestBase {
     $this->assertIdentical('image-test.png', $file->getFilename());
     $this->assertIdentical('public://image-test.png', $file->getFileUri());
     $this->assertIdentical('8', $file->getOwnerId());
-    $this->assertFalse($files);
+    $this->assertEmpty($files);
   }
 
 }
diff --git a/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserTest.php b/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserTest.php
index 5e2c663428c..558d3d01f8b 100644
--- a/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserTest.php
+++ b/core/modules/user/tests/src/Kernel/Migrate/d6/MigrateUserTest.php
@@ -141,7 +141,7 @@ class MigrateUserTest extends MigrateDrupal6TestBase {
       }
       else {
         // Ensure the user does not have a picture.
-        $this->assertFalse($user->user_picture->target_id, sprintf('User %s does not have a picture', $user->id()));
+        $this->assertEmpty($user->user_picture->target_id, sprintf('User %s does not have a picture', $user->id()));
       }
 
       // Use the API to check if the password has been salted and re-hashed to
diff --git a/core/modules/user/tests/src/Kernel/TempStoreDatabaseTest.php b/core/modules/user/tests/src/Kernel/TempStoreDatabaseTest.php
index 51a3b9f8e75..5a41180276d 100644
--- a/core/modules/user/tests/src/Kernel/TempStoreDatabaseTest.php
+++ b/core/modules/user/tests/src/Kernel/TempStoreDatabaseTest.php
@@ -143,8 +143,8 @@ class TempStoreDatabaseTest extends KernelTestBase {
       ->condition('collection', "user.shared_tempstore.$collection")
       ->condition('name', $key)
       ->execute();
-    $this->assertFalse($stores[0]->get($key));
-    $this->assertFalse($stores[1]->get($key));
+    $this->assertEmpty($stores[0]->get($key));
+    $this->assertEmpty($stores[1]->get($key));
   }
 
 }
diff --git a/core/modules/user/tests/src/Kernel/UserMailNotifyTest.php b/core/modules/user/tests/src/Kernel/UserMailNotifyTest.php
index 22bb8e28e28..521e80833cd 100644
--- a/core/modules/user/tests/src/Kernel/UserMailNotifyTest.php
+++ b/core/modules/user/tests/src/Kernel/UserMailNotifyTest.php
@@ -90,7 +90,7 @@ class UserMailNotifyTest extends EntityKernelTestBase {
   public function testUserMailsNotSent($op) {
     $this->config('user.settings')->set('notify.' . $op, FALSE)->save();
     $return = _user_mail_notify($op, $this->createUser());
-    $this->assertFalse($return);
+    $this->assertNull($return);
     $this->assertEmpty($this->getMails());
   }
 
diff --git a/core/modules/user/tests/src/Kernel/Views/HandlerArgumentUserUidTest.php b/core/modules/user/tests/src/Kernel/Views/HandlerArgumentUserUidTest.php
index dc51ed9946e..ee29794ec02 100644
--- a/core/modules/user/tests/src/Kernel/Views/HandlerArgumentUserUidTest.php
+++ b/core/modules/user/tests/src/Kernel/Views/HandlerArgumentUserUidTest.php
@@ -48,7 +48,7 @@ class HandlerArgumentUserUidTest extends KernelTestBase {
 
     // Tests an invalid user uid.
     $view->preview(NULL, [rand(1000, 10000)]);
-    $this->assertFalse($view->getTitle());
+    $this->assertEmpty($view->getTitle());
     $view->destroy();
 
     // Tests a valid user.
diff --git a/core/modules/views/src/Tests/AssertViewsCacheTagsTrait.php b/core/modules/views/src/Tests/AssertViewsCacheTagsTrait.php
index 5355a89b50d..26c1ffe0b52 100644
--- a/core/modules/views/src/Tests/AssertViewsCacheTagsTrait.php
+++ b/core/modules/views/src/Tests/AssertViewsCacheTagsTrait.php
@@ -66,14 +66,14 @@ trait AssertViewsCacheTagsTrait {
       $view->build();
       $results_cache_item = \Drupal::cache('data')->get($cache_plugin->generateResultsKey());
       if (is_array($expected_results_cache)) {
-        $this->assertTrue($results_cache_item, 'Results cache item found.');
+        $this->assertNotEmpty($results_cache_item, 'Results cache item found.');
         if ($results_cache_item) {
           sort($expected_results_cache);
           $this->assertEqual($results_cache_item->tags, $expected_results_cache);
         }
       }
       else {
-        $this->assertFalse($results_cache_item, 'Results cache item not found.');
+        $this->assertNull($results_cache_item, 'Results cache item not found.');
       }
 
       $this->pass('Checking Views render cache item cache tags.');
@@ -83,13 +83,13 @@ trait AssertViewsCacheTagsTrait {
 
       $render_cache_item = $render_cache->get($original);
       if ($views_caching_is_enabled === TRUE) {
-        $this->assertTrue(!empty($render_cache_item), 'Render cache item found.');
+        $this->assertNotEmpty($render_cache_item, 'Render cache item found.');
         if ($render_cache_item) {
           $this->assertEqual($render_cache_item['#cache']['tags'], $expected_render_array_cache_tags);
         }
       }
       else {
-        $this->assertFalse($render_cache_item, 'Render cache item not found.');
+        $this->assertNull($render_cache_item, 'Render cache item not found.');
       }
     }
 
diff --git a/core/modules/views/tests/src/Functional/BulkFormTest.php b/core/modules/views/tests/src/Functional/BulkFormTest.php
index 033902438e7..8f49155b889 100644
--- a/core/modules/views/tests/src/Functional/BulkFormTest.php
+++ b/core/modules/views/tests/src/Functional/BulkFormTest.php
@@ -53,7 +53,7 @@ class BulkFormTest extends BrowserTestBase {
 
     // Test that the views edit header appears first.
     $first_form_element = $this->xpath('//form/div[1][@id = :id]', [':id' => 'edit-header']);
-    $this->assertTrue($first_form_element, 'The views form edit header appears first.');
+    $this->assertNotEmpty($first_form_element, 'The views form edit header appears first.');
 
     $this->assertFieldById('edit-action', NULL, 'The action select field appears.');
 
@@ -152,7 +152,7 @@ class BulkFormTest extends BrowserTestBase {
     // Make sure we don't show an action message while we are still on the
     // confirmation page.
     $errors = $this->xpath('//div[contains(@class, "messages--status")]');
-    $this->assertFalse($errors, 'No action message shown.');
+    $this->assertEmpty($errors, 'No action message shown.');
     $this->drupalPostForm(NULL, [], t('Delete'));
     $this->assertText(t('Deleted 5 content items.'));
     // Check if we got redirected to the original page.
diff --git a/core/modules/views/tests/src/Functional/GlossaryTest.php b/core/modules/views/tests/src/Functional/GlossaryTest.php
index 04cda6e32b0..2adac436b25 100644
--- a/core/modules/views/tests/src/Functional/GlossaryTest.php
+++ b/core/modules/views/tests/src/Functional/GlossaryTest.php
@@ -117,7 +117,7 @@ class GlossaryTest extends ViewTestBase {
       // Get the summary link for a certain character. Filter by label and href
       // to ensure that both of them are correct.
       $result = $this->xpath('//a[contains(@href, :href) and normalize-space(text())=:label]/..', [':href' => $href, ':label' => $label]);
-      $this->assertTrue(count($result));
+      $this->assertNotEmpty(count($result));
       // The rendered output looks like "<a href=''>X</a> | (count)" so let's
       // figure out the int.
       $result_count = explode(' ', trim(str_replace(['|', '(', ')'], '', $result[0]->getText())))[1];
diff --git a/core/modules/views/tests/src/Functional/Handler/AreaTest.php b/core/modules/views/tests/src/Functional/Handler/AreaTest.php
index 170147eab00..9a257490564 100644
--- a/core/modules/views/tests/src/Functional/Handler/AreaTest.php
+++ b/core/modules/views/tests/src/Functional/Handler/AreaTest.php
@@ -168,7 +168,7 @@ class AreaTest extends ViewTestBase {
 
     // Test that the list is token present.
     $element = $this->xpath('//ul[@class="global-tokens"]');
-    $this->assertTrue($element, 'Token list found on the options form.');
+    $this->assertNotEmpty($element, 'Token list found on the options form.');
 
     $empty_handler = &$view->empty['test_example'];
 
diff --git a/core/modules/views/tests/src/Functional/Handler/FieldWebTest.php b/core/modules/views/tests/src/Functional/Handler/FieldWebTest.php
index 7b3e747a555..25026c9a077 100644
--- a/core/modules/views/tests/src/Functional/Handler/FieldWebTest.php
+++ b/core/modules/views/tests/src/Functional/Handler/FieldWebTest.php
@@ -352,7 +352,7 @@ class FieldWebTest extends ViewTestBase {
       return $id_field->theme($row);
     });
     $elements = $this->xpathContent($output, '//a[contains(@class, :class)]', [':class' => $class]);
-    $this->assertTrue($elements);
+    $this->assertNotEmpty($elements);
     // @fixme link_class, alt, rel cannot be unset, which should be fixed.
     $id_field->options['alter']['link_class'] = '';
 
@@ -362,7 +362,7 @@ class FieldWebTest extends ViewTestBase {
       return $id_field->theme($row);
     });
     $elements = $this->xpathContent($output, '//a[contains(@title, :alt)]', [':alt' => $rel]);
-    $this->assertTrue($elements);
+    $this->assertNotEmpty($elements);
     $id_field->options['alter']['alt'] = '';
 
     // Tests the rel setting.
@@ -371,7 +371,7 @@ class FieldWebTest extends ViewTestBase {
       return $id_field->theme($row);
     });
     $elements = $this->xpathContent($output, '//a[contains(@rel, :rel)]', [':rel' => $rel]);
-    $this->assertTrue($elements);
+    $this->assertNotEmpty($elements);
     $id_field->options['alter']['rel'] = '';
 
     // Tests the target setting.
@@ -380,7 +380,7 @@ class FieldWebTest extends ViewTestBase {
       return $id_field->theme($row);
     });
     $elements = $this->xpathContent($output, '//a[contains(@target, :target)]', [':target' => $target]);
-    $this->assertTrue($elements);
+    $this->assertNotEmpty($elements);
     unset($id_field->options['alter']['target']);
   }
 
@@ -401,16 +401,16 @@ class FieldWebTest extends ViewTestBase {
     $id_field->options['label'] = $this->randomMachineName();
     $output = $view->preview();
     $output = $renderer->renderRoot($output);
-    $this->assertFalse($this->xpathContent($output, '//div[contains(@class, :class)]', [':class' => 'field-content']));
-    $this->assertFalse($this->xpathContent($output, '//div[contains(@class, :class)]', [':class' => 'field__label']));
+    $this->assertEmpty($this->xpathContent($output, '//div[contains(@class, :class)]', [':class' => 'field-content']));
+    $this->assertEmpty($this->xpathContent($output, '//div[contains(@class, :class)]', [':class' => 'field__label']));
 
     $id_field->options['element_default_classes'] = TRUE;
     $output = $view->preview();
     $output = $renderer->renderRoot($output);
     // Per default the label and the element of the field are spans.
-    $this->assertTrue($this->xpathContent($output, '//span[contains(@class, :class)]', [':class' => 'field-content']));
-    $this->assertTrue($this->xpathContent($output, '//span[contains(@class, :class)]', [':class' => 'views-label']));
-    $this->assertTrue($this->xpathContent($output, '//div[contains(@class, :class)]', [':class' => 'views-field']));
+    $this->assertNotEmpty($this->xpathContent($output, '//span[contains(@class, :class)]', [':class' => 'field-content']));
+    $this->assertNotEmpty($this->xpathContent($output, '//span[contains(@class, :class)]', [':class' => 'views-label']));
+    $this->assertNotEmpty($this->xpathContent($output, '//div[contains(@class, :class)]', [':class' => 'views-field']));
 
     // Tests the element wrapper classes/element.
     $random_class = $this->randomMachineName();
@@ -423,14 +423,14 @@ class FieldWebTest extends ViewTestBase {
       $id_field->options['element_wrapper_class'] = $random_class;
       $output = $view->preview();
       $output = $renderer->renderRoot($output);
-      $this->assertTrue($this->xpathContent($output, "//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
+      $this->assertNotEmpty($this->xpathContent($output, "//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
 
       // Set no custom css class.
       $id_field->options['element_wrapper_class'] = '';
       $output = $view->preview();
       $output = $renderer->renderRoot($output);
-      $this->assertFalse($this->xpathContent($output, "//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
-      $this->assertTrue($this->xpathContent($output, "//li[contains(@class, views-row)]/{$element_type}"));
+      $this->assertEmpty($this->xpathContent($output, "//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
+      $this->assertNotEmpty($this->xpathContent($output, "//li[contains(@class, views-row)]/{$element_type}"));
     }
 
     // Tests the label class/element.
@@ -443,14 +443,14 @@ class FieldWebTest extends ViewTestBase {
       $id_field->options['element_label_class'] = $random_class;
       $output = $view->preview();
       $output = $renderer->renderRoot($output);
-      $this->assertTrue($this->xpathContent($output, "//li[contains(@class, views-row)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
+      $this->assertNotEmpty($this->xpathContent($output, "//li[contains(@class, views-row)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
 
       // Set no custom css class.
       $id_field->options['element_label_class'] = '';
       $output = $view->preview();
       $output = $renderer->renderRoot($output);
-      $this->assertFalse($this->xpathContent($output, "//li[contains(@class, views-row)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
-      $this->assertTrue($this->xpathContent($output, "//li[contains(@class, views-row)]//{$element_type}"));
+      $this->assertEmpty($this->xpathContent($output, "//li[contains(@class, views-row)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
+      $this->assertNotEmpty($this->xpathContent($output, "//li[contains(@class, views-row)]//{$element_type}"));
     }
 
     // Tests the element classes/element.
@@ -463,14 +463,14 @@ class FieldWebTest extends ViewTestBase {
       $id_field->options['element_class'] = $random_class;
       $output = $view->preview();
       $output = $renderer->renderRoot($output);
-      $this->assertTrue($this->xpathContent($output, "//li[contains(@class, views-row)]//div[contains(@class, views-field)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
+      $this->assertNotEmpty($this->xpathContent($output, "//li[contains(@class, views-row)]//div[contains(@class, views-field)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
 
       // Set no custom css class.
       $id_field->options['element_class'] = '';
       $output = $view->preview();
       $output = $renderer->renderRoot($output);
-      $this->assertFalse($this->xpathContent($output, "//li[contains(@class, views-row)]//div[contains(@class, views-field)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
-      $this->assertTrue($this->xpathContent($output, "//li[contains(@class, views-row)]//div[contains(@class, views-field)]//{$element_type}"));
+      $this->assertEmpty($this->xpathContent($output, "//li[contains(@class, views-row)]//div[contains(@class, views-field)]//{$element_type}[contains(@class, :class)]", [':class' => $random_class]));
+      $this->assertNotEmpty($this->xpathContent($output, "//li[contains(@class, views-row)]//div[contains(@class, views-field)]//{$element_type}"));
     }
 
     // Tests the available html elements.
@@ -635,14 +635,14 @@ class FieldWebTest extends ViewTestBase {
       return $name_field->advancedRender($row);
     });
     $this->assertSubString($output, $more_text, 'Make sure a read more text is displayed if the output got trimmed');
-    $this->assertTrue($this->xpathContent($output, '//a[contains(@href, :path)]', [':path' => $more_path]), 'Make sure the read more link points to the right destination.');
+    $this->assertNotEmpty($this->xpathContent($output, '//a[contains(@href, :path)]', [':path' => $more_path]), 'Make sure the read more link points to the right destination.');
 
     $name_field->options['alter']['more_link'] = FALSE;
     $output = $renderer->executeInRenderContext(new RenderContext(), function () use ($name_field, $row) {
       return $name_field->advancedRender($row);
     });
     $this->assertNotSubString($output, $more_text, 'Make sure no read more text appears.');
-    $this->assertFalse($this->xpathContent($output, '//a[contains(@href, :path)]', [':path' => $more_path]), 'Make sure no read more link appears.');
+    $this->assertEmpty($this->xpathContent($output, '//a[contains(@href, :path)]', [':path' => $more_path]), 'Make sure no read more link appears.');
 
     // Check for the ellipses.
     $row->views_test_data_name = $this->randomMachineName(8);
diff --git a/core/modules/views/tests/src/Functional/Handler/HandlerTest.php b/core/modules/views/tests/src/Functional/Handler/HandlerTest.php
index 08ee8f7cbf2..0dcfdd03179 100644
--- a/core/modules/views/tests/src/Functional/Handler/HandlerTest.php
+++ b/core/modules/views/tests/src/Functional/Handler/HandlerTest.php
@@ -310,15 +310,15 @@ class HandlerTest extends ViewTestBase {
 
     $field->options['relationship'] = NULL;
     $field->setRelationship();
-    $this->assertFalse($field->relationship, 'Make sure that an empty relationship does not create a relationship on the field.');
+    $this->assertNull($field->relationship, 'Make sure that an empty relationship does not create a relationship on the field.');
 
     $field->options['relationship'] = $this->randomMachineName();
     $field->setRelationship();
-    $this->assertFalse($field->relationship, 'Make sure that a random relationship does not create a relationship on the field.');
+    $this->assertNull($field->relationship, 'Make sure that a random relationship does not create a relationship on the field.');
 
     $field->options['relationship'] = 'broken_relationship';
     $field->setRelationship();
-    $this->assertFalse($field->relationship, 'Make sure that a broken relationship does not create a relationship on the field.');
+    $this->assertNull($field->relationship, 'Make sure that a broken relationship does not create a relationship on the field.');
 
     $field->options['relationship'] = 'valid_relationship';
     $field->setRelationship();
diff --git a/core/modules/views/tests/src/Functional/Plugin/ArgumentDefaultTest.php b/core/modules/views/tests/src/Functional/Plugin/ArgumentDefaultTest.php
index fe6ff11510f..3fcc13a044e 100644
--- a/core/modules/views/tests/src/Functional/Plugin/ArgumentDefaultTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/ArgumentDefaultTest.php
@@ -166,9 +166,9 @@ class ArgumentDefaultTest extends ViewTestBase {
     $this->drupalPlaceBlock("views_block:test_argument_default_node-block_1", ['id' => $id]);
     $xpath = '//*[@id="block-' . $id . '"]';
     $this->drupalGet('node/' . $node1->id());
-    $this->assertTrue(strpos($this->xpath($xpath)[0]->getText(), $node1->getTitle()));
+    $this->assertContains($node1->getTitle(), $this->xpath($xpath)[0]->getText());
     $this->drupalGet('node/' . $node2->id());
-    $this->assertTrue(strpos($this->xpath($xpath)[0]->getText(), $node2->getTitle()));
+    $this->assertContains($node2->getTitle(), $this->xpath($xpath)[0]->getText());
   }
 
   /**
diff --git a/core/modules/views/tests/src/Functional/Plugin/CacheTagTest.php b/core/modules/views/tests/src/Functional/Plugin/CacheTagTest.php
index 1adba7d801b..fb4504587b1 100644
--- a/core/modules/views/tests/src/Functional/Plugin/CacheTagTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/CacheTagTest.php
@@ -129,7 +129,7 @@ class CacheTagTest extends ViewTestBase {
     // Saving the view should invalidate the tags.
     $cache_plugin = $view->display_handler->getPlugin('cache');
     $this->assertTrue($cache_plugin->cacheGet('results'), 'Results cache found.');
-    $this->assertTrue($this->getRenderCache($view), 'Output cache found.');
+    $this->assertNotEmpty($this->getRenderCache($view), 'Output cache found.');
 
     $view->storage->save();
 
@@ -143,7 +143,7 @@ class CacheTagTest extends ViewTestBase {
     // Test invalidating the nodes in this view invalidates the cache.
     $cache_plugin = $view->display_handler->getPlugin('cache');
     $this->assertTrue($cache_plugin->cacheGet('results'), 'Results cache found.');
-    $this->assertTrue($this->getRenderCache($view), 'Output cache found.');
+    $this->assertNotEmpty($this->getRenderCache($view), 'Output cache found.');
 
     $this->nodeViewBuilder->resetCache($this->pages);
 
@@ -157,7 +157,7 @@ class CacheTagTest extends ViewTestBase {
     // Test saving a node in this view invalidates the cache.
     $cache_plugin = $view->display_handler->getPlugin('cache');
     $this->assertTrue($cache_plugin->cacheGet('results'), 'Results cache found.');
-    $this->assertTrue($this->getRenderCache($view), 'Output cache found.');
+    $this->assertNotEmpty($this->getRenderCache($view), 'Output cache found.');
 
     $node = reset($this->pages);
     $node->save();
@@ -172,7 +172,7 @@ class CacheTagTest extends ViewTestBase {
     // Test saving a node not in this view invalidates the cache too.
     $cache_plugin = $view->display_handler->getPlugin('cache');
     $this->assertTrue($cache_plugin->cacheGet('results'), 'Results cache found.');
-    $this->assertTrue($this->getRenderCache($view), 'Output cache found.');
+    $this->assertNotEmpty($this->getRenderCache($view), 'Output cache found.');
 
     $this->article->save();
 
@@ -187,13 +187,13 @@ class CacheTagTest extends ViewTestBase {
     // as the user entity type will not be contained in the views cache tags.
     $cache_plugin = $view->display_handler->getPlugin('cache');
     $this->assertTrue($cache_plugin->cacheGet('results'), 'Results cache found.');
-    $this->assertTrue($this->getRenderCache($view), 'Output cache found.');
+    $this->assertNotEmpty($this->getRenderCache($view), 'Output cache found.');
 
     $this->userViewBuilder->resetCache([$this->user]);
 
     $cache_plugin = $view->display_handler->getPlugin('cache');
     $this->assertTrue($cache_plugin->cacheGet('results'), 'Results cache found after a user is invalidated.');
-    $this->assertTrue($this->getRenderCache($view), 'Output cache found after a user is invalidated.');
+    $this->assertNotEmpty($this->getRenderCache($view), 'Output cache found after a user is invalidated.');
 
     $view->destroy();
     // Invalidate the views cache tags in order to invalidate the render
@@ -205,7 +205,7 @@ class CacheTagTest extends ViewTestBase {
     // Test the cacheFlush method invalidates the cache.
     $cache_plugin = $view->display_handler->getPlugin('cache');
     $this->assertTrue($cache_plugin->cacheGet('results'), 'Results cache found.');
-    $this->assertTrue($this->getRenderCache($view), 'Output cache found.');
+    $this->assertNotEmpty($this->getRenderCache($view), 'Output cache found.');
 
     $cache_plugin->cacheFlush();
 
diff --git a/core/modules/views/tests/src/Functional/Plugin/CacheWebTest.php b/core/modules/views/tests/src/Functional/Plugin/CacheWebTest.php
index 016c0abd8c3..cf7b6a25cef 100644
--- a/core/modules/views/tests/src/Functional/Plugin/CacheWebTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/CacheWebTest.php
@@ -70,7 +70,7 @@ class CacheWebTest extends ViewTestBase {
 
     $this->drupalGet('test-display');
     $this->assertResponse(200);
-    $this->assertTrue($render_cache->get($cache_element));
+    $this->assertNotEmpty($render_cache->get($cache_element));
     $cache_tags = [
       'config:user.role.anonymous',
       'config:views.view.test_display',
@@ -81,7 +81,7 @@ class CacheWebTest extends ViewTestBase {
 
     $this->drupalGet('test-display');
     $this->assertResponse(200);
-    $this->assertTrue($render_cache->get($cache_element));
+    $this->assertNotEmpty($render_cache->get($cache_element));
     $this->assertCacheTags($cache_tags);
   }
 
diff --git a/core/modules/views/tests/src/Functional/Plugin/DisplayFeedTest.php b/core/modules/views/tests/src/Functional/Plugin/DisplayFeedTest.php
index 456450f8073..712f6c49f5a 100644
--- a/core/modules/views/tests/src/Functional/Plugin/DisplayFeedTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/DisplayFeedTest.php
@@ -92,7 +92,7 @@ class DisplayFeedTest extends ViewTestBase {
     $this->drupalPlaceBlock('views_block:test_display_feed-test');
     $this->drupalGet('<front>');
     $feed_icon = $this->cssSelect('div.view-id-test_display_feed a.feed-icon');
-    $this->assertTrue(strpos($feed_icon[0]->getAttribute('href'), 'test-feed-display.xml'), 'The feed icon was found.');
+    $this->assertContains('test-feed-display.xml', $feed_icon[0]->getAttribute('href'), 'The feed icon was found.');
 
     // Test feed display attached to page display with arguments.
     $this->drupalGet('test-feed-icon/' . $node->id());
@@ -148,7 +148,7 @@ class DisplayFeedTest extends ViewTestBase {
     $this->drupalGet('/test-attached-disabled');
     $feed_header = $this->xpath('//link[@rel="alternate"]');
     $this->assertEqual($feed_header[0]->getAttribute('type'), 'application/rss+xml', 'The feed link has the type application/rss+xml.');
-    $this->assertTrue(strpos($feed_header[0]->getAttribute('href'), 'test-attached-disabled.xml'), 'Page display contains the correct feed URL.');
+    $this->assertContains('test-attached-disabled.xml', $feed_header[0]->getAttribute('href'), 'Page display contains the correct feed URL.');
 
     // Disable the feed display.
     $view->displayHandlers->get('feed_1')->setOption('enabled', FALSE);
diff --git a/core/modules/views/tests/src/Functional/Plugin/DisplayPageWebTest.php b/core/modules/views/tests/src/Functional/Plugin/DisplayPageWebTest.php
index d361db0e4b1..afcaf31d1d4 100644
--- a/core/modules/views/tests/src/Functional/Plugin/DisplayPageWebTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/DisplayPageWebTest.php
@@ -140,7 +140,7 @@ class DisplayPageWebTest extends ViewTestBase {
 
     $view = Views::getView('test_page_display');
     $xpath = $this->cssSelect('div.view:contains("' . $view->getTitle() . '")');
-    $this->assertFalse($xpath, 'The view title was not displayed in the view markup.');
+    $this->assertEmpty($xpath, 'The view title was not displayed in the view markup.');
   }
 
   /**
diff --git a/core/modules/views/tests/src/Functional/Plugin/DisplayTest.php b/core/modules/views/tests/src/Functional/Plugin/DisplayTest.php
index 1b2adc228cf..17154476a9d 100644
--- a/core/modules/views/tests/src/Functional/Plugin/DisplayTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/DisplayTest.php
@@ -389,7 +389,7 @@ class DisplayTest extends ViewTestBase {
     ];
     $view->setHandler('default', 'filter', 'id', $item);
     $this->executeView($view);
-    $this->assertFalse(count($view->result), 'Ensure the result of the view is empty.');
+    $this->assertEmpty($view->result, 'Ensure the result of the view is empty.');
     $this->assertFalse($view->display_handler->outputIsEmpty(), 'Ensure the view output is marked as not empty, because the empty text still appears.');
     $view->destroy();
 
@@ -399,7 +399,7 @@ class DisplayTest extends ViewTestBase {
     $item['empty'] = TRUE;
     $view->setHandler('default', 'header', 'area', $item);
     $this->executeView($view);
-    $this->assertFalse(count($view->result), 'Ensure the result of the view is empty.');
+    $this->assertEmpty($view->result, 'Ensure the result of the view is empty.');
     $this->assertFalse($view->display_handler->outputIsEmpty(), 'Ensure the view output is marked as not empty, because the header text still appears.');
     $view->destroy();
 
@@ -408,7 +408,7 @@ class DisplayTest extends ViewTestBase {
     $item['empty'] = FALSE;
     $view->setHandler('default', 'header', 'area', $item);
     $this->executeView($view);
-    $this->assertFalse(count($view->result), 'Ensure the result of the view is empty.');
+    $this->assertEmpty($view->result, 'Ensure the result of the view is empty.');
     $this->assertTrue($view->display_handler->outputIsEmpty(), 'Ensure the view output is marked as empty.');
   }
 
diff --git a/core/modules/views/tests/src/Functional/Plugin/ExposedFormTest.php b/core/modules/views/tests/src/Functional/Plugin/ExposedFormTest.php
index 6240fb04121..df7c0a5ed4a 100644
--- a/core/modules/views/tests/src/Functional/Plugin/ExposedFormTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/ExposedFormTest.php
@@ -374,14 +374,14 @@ class ExposedFormTest extends ViewTestBase {
     $this->drupalGet('views_test_data_error_form_page');
     $this->assertResponse(200);
     $form = $this->cssSelect('form.views-exposed-form');
-    $this->assertTrue($form, 'The exposed form element was found.');
+    $this->assertNotEmpty($form, 'The exposed form element was found.');
     $this->assertRaw(t('Apply'), 'Ensure the exposed form is rendered before submitting the normal form.');
     $this->assertRaw('<div class="views-row">', 'Views result shown.');
 
     $this->drupalPostForm(NULL, [], t('Submit'));
     $this->assertResponse(200);
     $form = $this->cssSelect('form.views-exposed-form');
-    $this->assertTrue($form, 'The exposed form element was found.');
+    $this->assertNotEmpty($form, 'The exposed form element was found.');
     $this->assertRaw(t('Apply'), 'Ensure the exposed form is rendered after submitting the normal form.');
     $this->assertRaw('<div class="views-row">', 'Views result shown.');
   }
diff --git a/core/modules/views/tests/src/Functional/Plugin/StyleTableTest.php b/core/modules/views/tests/src/Functional/Plugin/StyleTableTest.php
index 3af722395d4..7201c933501 100644
--- a/core/modules/views/tests/src/Functional/Plugin/StyleTableTest.php
+++ b/core/modules/views/tests/src/Functional/Plugin/StyleTableTest.php
@@ -42,15 +42,15 @@ class StyleTableTest extends ViewTestBase {
     $this->drupalGet('test-table');
 
     $result = $this->xpath('//caption/child::text()');
-    $this->assertTrue(count($result), 'The caption appears on the table.');
+    $this->assertNotEmpty($result, 'The caption appears on the table.');
     $this->assertEqual(trim($result[0]->getText()), 'caption-text');
 
     $result = $this->xpath('//summary/child::text()');
-    $this->assertTrue(count($result), 'The summary appears on the table.');
+    $this->assertNotEmpty($result, 'The summary appears on the table.');
     $this->assertEqual(trim($result[0]->getText()), 'summary-text');
 
     $result = $this->xpath('//caption/details/child::text()[normalize-space()]');
-    $this->assertTrue(count($result), 'The table description appears on the table.');
+    $this->assertNotEmpty($result, 'The table description appears on the table.');
     $this->assertEqual(trim($result[0]->getText()), 'description-text');
 
     // Remove the caption and ensure the caption is not displayed anymore.
@@ -61,7 +61,7 @@ class StyleTableTest extends ViewTestBase {
 
     $this->drupalGet('test-table');
     $result = $this->xpath('//caption/child::text()');
-    $this->assertFalse(trim($result[0]->getText()), 'Ensure that the caption disappears.');
+    $this->assertEmpty(trim($result[0]->getText()), 'Ensure that the caption disappears.');
 
     // Remove the table summary.
     $display = &$view->getDisplay('default');
@@ -70,7 +70,7 @@ class StyleTableTest extends ViewTestBase {
 
     $this->drupalGet('test-table');
     $result = $this->xpath('//summary/child::text()');
-    $this->assertFalse(count($result), 'Ensure that the summary disappears.');
+    $this->assertEmpty($result, 'Ensure that the summary disappears.');
 
     // Remove the table description.
     $display = &$view->getDisplay('default');
@@ -79,7 +79,7 @@ class StyleTableTest extends ViewTestBase {
 
     $this->drupalGet('test-table');
     $result = $this->xpath('//caption/details/child::text()[normalize-space()]');
-    $this->assertFalse(count($result), 'Ensure that the description disappears.');
+    $this->assertEmpty($result, 'Ensure that the description disappears.');
   }
 
   /**
@@ -93,9 +93,9 @@ class StyleTableTest extends ViewTestBase {
     // do: "views-field-job-1" would also contain "views-field-job".
     // @see Drupal\system\Tests\Form\ElementTest::testButtonClasses().
     $result = $this->xpath('//tbody/tr/td[contains(concat(" ", @class, " "), " views-field-job ")]');
-    $this->assertTrue(count($result), 'Ensure there is a td with the class views-field-job');
+    $this->assertGreaterThan(0, count($result), 'Ensure there is a td with the class views-field-job');
     $result = $this->xpath('//tbody/tr/td[contains(concat(" ", @class, " "), " views-field-job-1 ")]');
-    $this->assertTrue(count($result), 'Ensure there is a td with the class views-field-job-1');
+    $this->assertGreaterThan(0, count($result), 'Ensure there is a td with the class views-field-job-1');
 
     // Combine the second job-column with the first one, with ', ' as separator.
     $view = View::load('test_table');
@@ -108,10 +108,10 @@ class StyleTableTest extends ViewTestBase {
     $this->drupalGet('test-table');
 
     $result = $this->xpath('//tbody/tr/td[contains(concat(" ", @class, " "), " views-field-job views-field-job-1 ")]');
-    $this->assertTrue(count($result), 'Ensure that the job column class names are joined into a single column');
+    $this->assertGreaterThan(0, count($result), 'Ensure that the job column class names are joined into a single column');
 
     $result = $this->xpath('//tbody/tr/td[contains(., "Drummer, Drummer")]');
-    $this->assertTrue(count($result), 'Ensure the job column values are joined into a single column');
+    $this->assertGreaterThan(0, count($result), 'Ensure the job column values are joined into a single column');
   }
 
   /**
@@ -135,10 +135,10 @@ class StyleTableTest extends ViewTestBase {
     $this->drupalGet('test-table');
 
     $result = $this->xpath('//tbody/tr/td[contains(., "Baby")]');
-    $this->assertTrue(count($result), 'Ensure that the baby is found.');
+    $this->assertGreaterThan(0, count($result), 'Ensure that the baby is found.');
 
     $result = $this->xpath('//tbody/tr/td[text()=0]');
-    $this->assertTrue(count($result), 'Ensure that the baby\'s age is shown');
+    $this->assertGreaterThan(0, count($result), 'Ensure that the baby\'s age is shown');
   }
 
   /**
diff --git a/core/modules/views/tests/src/Functional/ViewElementTest.php b/core/modules/views/tests/src/Functional/ViewElementTest.php
index b682df7604b..773e776be39 100644
--- a/core/modules/views/tests/src/Functional/ViewElementTest.php
+++ b/core/modules/views/tests/src/Functional/ViewElementTest.php
@@ -42,10 +42,10 @@ class ViewElementTest extends ViewTestBase {
     $this->drupalGet('views_test_data_element_form');
 
     $xpath = $this->xpath('//div[@class="views-element-container js-form-wrapper form-wrapper"]');
-    $this->assertTrue($xpath, 'The view container has been found on the form.');
+    $this->assertNotEmpty($xpath, 'The view container has been found on the form.');
 
     $xpath = $this->xpath('//div[@class="view-content"]');
-    $this->assertTrue($xpath, 'The view content has been found on the form.');
+    $this->assertNotEmpty($xpath, 'The view content has been found on the form.');
     // There should be 5 rows in the results.
     $xpath = $this->xpath('//div[@class="view-content"]/div');
     $this->assertEqual(count($xpath), 5);
@@ -87,10 +87,10 @@ class ViewElementTest extends ViewTestBase {
     $this->drupalGet('views_test_data_element_embed_form');
 
     $xpath = $this->xpath('//div[@class="views-element-container js-form-wrapper form-wrapper"]');
-    $this->assertTrue($xpath, 'The view container has been found on the form.');
+    $this->assertNotEmpty($xpath, 'The view container has been found on the form.');
 
     $xpath = $this->xpath('//div[@class="view-content"]');
-    $this->assertTrue($xpath, 'The view content has been found on the form.');
+    $this->assertNotEmpty($xpath, 'The view content has been found on the form.');
     // There should be 5 rows in the results.
     $xpath = $this->xpath('//div[@class="view-content"]/div');
     $this->assertEqual(count($xpath), 5);
diff --git a/core/modules/views/tests/src/FunctionalJavascript/Plugin/views/Handler/GroupedExposedFilterTest.php b/core/modules/views/tests/src/FunctionalJavascript/Plugin/views/Handler/GroupedExposedFilterTest.php
index e61e8eaff36..bda1fbbd7c4 100644
--- a/core/modules/views/tests/src/FunctionalJavascript/Plugin/views/Handler/GroupedExposedFilterTest.php
+++ b/core/modules/views/tests/src/FunctionalJavascript/Plugin/views/Handler/GroupedExposedFilterTest.php
@@ -90,21 +90,21 @@ class GroupedExposedFilterTest extends WebDriverTestBase {
     $weight = $page->findField('options[group_info][group_items][1][weight]');
 
     // If there are 3 items, values from -3 to 3 should be available.
-    $this->assertFalse($weight->find('named', ['option', -4]));
+    $this->assertNull($weight->find('named', ['option', -4]));
     foreach (range(-3, 3) as $value) {
-      $this->assertTrue($weight->find('named', ['option', $value]));
+      $this->assertNotEmpty($weight->find('named', ['option', $value]));
     }
-    $this->assertFalse($weight->find('named', ['option', 4]));
+    $this->assertEmpty($weight->find('named', ['option', 4]));
 
     $page->pressButton("Add another item");
     $web_assert->waitForField('options[group_info][group_items][4][title]');
 
     // A new items was added, weight options should now be -4 to 4.
-    $this->assertFalse($weight->find('named', ['option', -5]));
+    $this->assertEmpty($weight->find('named', ['option', -5]));
     foreach (range(-4, 4) as $value) {
-      $this->assertTrue($weight->find('named', ['option', $value]));
+      $this->assertNotEmpty($weight->find('named', ['option', $value]));
     }
-    $this->assertFalse($weight->find('named', ['option', 5]));
+    $this->assertEmpty($weight->find('named', ['option', 5]));
   }
 
 }
diff --git a/core/modules/views/tests/src/Kernel/Entity/LatestRevisionFilterTest.php b/core/modules/views/tests/src/Kernel/Entity/LatestRevisionFilterTest.php
index 54e95283f46..91177746aee 100644
--- a/core/modules/views/tests/src/Kernel/Entity/LatestRevisionFilterTest.php
+++ b/core/modules/views/tests/src/Kernel/Entity/LatestRevisionFilterTest.php
@@ -131,7 +131,7 @@ class LatestRevisionFilterTest extends ViewsKernelTestBase {
     $found_revision_ids = array_filter($view->result, function ($row) use ($not_expected_revision_ids) {
       return in_array($row->vid, $not_expected_revision_ids);
     });
-    $this->assertFalse($found_revision_ids);
+    $this->assertEmpty($found_revision_ids);
   }
 
 }
diff --git a/core/modules/views/tests/src/Kernel/Handler/AreaTitleTest.php b/core/modules/views/tests/src/Kernel/Handler/AreaTitleTest.php
index 8c16b63088d..b84c718cce8 100644
--- a/core/modules/views/tests/src/Kernel/Handler/AreaTitleTest.php
+++ b/core/modules/views/tests/src/Kernel/Handler/AreaTitleTest.php
@@ -29,7 +29,7 @@ class AreaTitleTest extends ViewsKernelTestBase {
     $view->setDisplay('default');
     $this->executeView($view);
     $view->render();
-    $this->assertFalse($view->getTitle(), 'The title area does not override the title if the view is not empty.');
+    $this->assertEmpty($view->getTitle(), 'The title area does not override the title if the view is not empty.');
     $view->destroy();
 
     $view->setDisplay('default');
diff --git a/core/modules/views/tests/src/Kernel/Handler/FieldCustomTest.php b/core/modules/views/tests/src/Kernel/Handler/FieldCustomTest.php
index 599052dcbf1..8f55e95d5f2 100644
--- a/core/modules/views/tests/src/Kernel/Handler/FieldCustomTest.php
+++ b/core/modules/views/tests/src/Kernel/Handler/FieldCustomTest.php
@@ -86,7 +86,7 @@ class FieldCustomTest extends ViewsKernelTestBase {
     $output = $renderer->renderRoot($preview);
 
     $expected_text = 'Amount of kittens: ' . $view->style_plugin->getField(0, 'age');
-    $this->assertTrue(strpos((string) $output, $expected_text), 'The views token has been successfully replaced.');
+    $this->assertContains($expected_text, (string) $output, 'The views token has been successfully replaced.');
   }
 
   /**
diff --git a/core/modules/views/tests/src/Kernel/Plugin/CacheTest.php b/core/modules/views/tests/src/Kernel/Plugin/CacheTest.php
index a0980a10739..c8793bc8829 100644
--- a/core/modules/views/tests/src/Kernel/Plugin/CacheTest.php
+++ b/core/modules/views/tests/src/Kernel/Plugin/CacheTest.php
@@ -341,7 +341,7 @@ class CacheTest extends ViewsKernelTestBase {
 
     // Assert there are results, empty results would mean this test case would
     // pass otherwise.
-    $this->assertTrue(count($cache->data['result']), 'Results saved in cached data.');
+    $this->assertGreaterThan(0, count($cache->data['result']), 'Results saved in cached data.');
 
     // Assert each row doesn't contain '_entity' or '_relationship_entities'
     // items.
diff --git a/core/modules/views/tests/src/Kernel/Plugin/Display/ViewsMenuLinkTest.php b/core/modules/views/tests/src/Kernel/Plugin/Display/ViewsMenuLinkTest.php
index f24e956032b..c407f111fbc 100644
--- a/core/modules/views/tests/src/Kernel/Plugin/Display/ViewsMenuLinkTest.php
+++ b/core/modules/views/tests/src/Kernel/Plugin/Display/ViewsMenuLinkTest.php
@@ -55,36 +55,36 @@ class ViewsMenuLinkTest extends ViewsKernelTestBase {
   public function testMenuLinkOverrides() {
     // Link from views module.
     $views_link = $this->menuLinkManager->getDefinition('views_view:views.test_page_display_menu.page_3');
-    $this->assertTrue($views_link['enabled'], 'Menu link is enabled.');
-    $this->assertFalse($views_link['expanded'], 'Menu link is not expanded.');
+    $this->assertTrue((bool) $views_link['enabled'], 'Menu link is enabled.');
+    $this->assertFalse((bool) $views_link['expanded'], 'Menu link is not expanded.');
     $views_link['enabled'] = 0;
     $views_link['expanded'] = 1;
     $this->menuLinkManager->updateDefinition($views_link['id'], $views_link);
     $views_link = $this->menuLinkManager->getDefinition($views_link['id']);
-    $this->assertFalse($views_link['enabled'], 'Menu link is disabled.');
-    $this->assertTrue($views_link['expanded'], 'Menu link is expanded.');
+    $this->assertFalse((bool) $views_link['enabled'], 'Menu link is disabled.');
+    $this->assertTrue((bool) $views_link['expanded'], 'Menu link is expanded.');
     $this->menuLinkManager->rebuild();
-    $this->assertFalse($views_link['enabled'], 'Menu link is disabled.');
-    $this->assertTrue($views_link['expanded'], 'Menu link is expanded.');
+    $this->assertFalse((bool) $views_link['enabled'], 'Menu link is disabled.');
+    $this->assertTrue((bool) $views_link['expanded'], 'Menu link is expanded.');
 
     // Link from user module.
     $user_link = $this->menuLinkManager->getDefinition('user.page');
-    $this->assertTrue($user_link['enabled'], 'Menu link is enabled.');
+    $this->assertTrue((bool) $user_link['enabled'], 'Menu link is enabled.');
     $user_link['enabled'] = 0;
     $views_link['expanded'] = 1;
     $this->menuLinkManager->updateDefinition($user_link['id'], $user_link);
-    $this->assertFalse($user_link['enabled'], 'Menu link is disabled.');
+    $this->assertFalse((bool) $user_link['enabled'], 'Menu link is disabled.');
     $this->menuLinkManager->rebuild();
-    $this->assertFalse($user_link['enabled'], 'Menu link is disabled.');
+    $this->assertFalse((bool) $user_link['enabled'], 'Menu link is disabled.');
 
     $this->menuLinkOverrides->reload();
 
     $views_link = $this->menuLinkManager->getDefinition('views_view:views.test_page_display_menu.page_3');
-    $this->assertFalse($views_link['enabled'], 'Menu link is disabled.');
-    $this->assertTrue($views_link['expanded'], 'Menu link is expanded.');
+    $this->assertFalse((bool) $views_link['enabled'], 'Menu link is disabled.');
+    $this->assertTrue((bool) $views_link['expanded'], 'Menu link is expanded.');
 
     $user_link = $this->menuLinkManager->getDefinition('user.page');
-    $this->assertFalse($user_link['enabled'], 'Menu link is disabled.');
+    $this->assertFalse((bool) $user_link['enabled'], 'Menu link is disabled.');
   }
 
 }
diff --git a/core/modules/views/tests/src/Kernel/Plugin/QueryTest.php b/core/modules/views/tests/src/Kernel/Plugin/QueryTest.php
index 02548b25c90..d3f4f162ebf 100644
--- a/core/modules/views/tests/src/Kernel/Plugin/QueryTest.php
+++ b/core/modules/views/tests/src/Kernel/Plugin/QueryTest.php
@@ -44,7 +44,7 @@ class QueryTest extends ViewsKernelTestBase {
     $view->setDisplay();
 
     $view->initQuery();
-    $this->assertTrue($view->query instanceof QueryTestPlugin, 'Make sure the right query plugin got instantiated.');
+    $this->assertInstanceOf(QueryTestPlugin::class, $view->query, 'Make sure the right query plugin got instantiated.');
   }
 
   public function _testQueryExecute() {
@@ -55,7 +55,7 @@ class QueryTest extends ViewsKernelTestBase {
     $view->query->setAllItems($this->dataSet());
 
     $this->executeView($view);
-    $this->assertTrue($view->result, 'Make sure the view result got filled');
+    $this->assertNotEmpty($view->result, 'Make sure the view result got filled');
   }
 
   /**
@@ -68,7 +68,7 @@ class QueryTest extends ViewsKernelTestBase {
     $view->setDisplay();
 
     $view->initQuery();
-    $this->assertFalse($view->query->getLimit(), 'Default to an empty limit.');
+    $this->assertNull($view->query->getLimit(), 'Default to an empty limit.');
     $rand_number = rand(5, 10);
     $view->query->setLimit($rand_number);
     $this->assertEqual($view->query->getLimit(), $rand_number, 'set_limit adapts the amount of items.');
diff --git a/core/modules/views/tests/src/Kernel/Plugin/RowRenderCacheTest.php b/core/modules/views/tests/src/Kernel/Plugin/RowRenderCacheTest.php
index a87ede5ffc3..3f1a2fbf5b5 100644
--- a/core/modules/views/tests/src/Kernel/Plugin/RowRenderCacheTest.php
+++ b/core/modules/views/tests/src/Kernel/Plugin/RowRenderCacheTest.php
@@ -195,7 +195,7 @@ class RowRenderCacheTest extends ViewsKernelTestBase {
           ],
         ];
         $element = $render_cache->get($cache);
-        $this->assertTrue($element);
+        $this->assertNotEmpty($element);
       }
 
       $index++;
diff --git a/core/modules/views/tests/src/Kernel/Plugin/StyleGridTest.php b/core/modules/views/tests/src/Kernel/Plugin/StyleGridTest.php
index 1ef2009d56b..f725d769e64 100644
--- a/core/modules/views/tests/src/Kernel/Plugin/StyleGridTest.php
+++ b/core/modules/views/tests/src/Kernel/Plugin/StyleGridTest.php
@@ -64,7 +64,7 @@ class StyleGridTest extends PluginKernelTestBase {
     $this->setRawContent($output);
     if (!in_array($alignment, $this->alignmentsTested)) {
       $result = $this->xpath('//div[contains(@class, "views-view-grid") and contains(@class, :alignment) and contains(@class, :columns)]', [':alignment' => $alignment, ':columns' => 'cols-' . $columns]);
-      $this->assertTrue(count($result), ucfirst($alignment) . " grid markup detected.");
+      $this->assertGreaterThan(0, count($result), ucfirst($alignment) . " grid markup detected.");
       $this->alignmentsTested[] = $alignment;
     }
     $width = '0';
@@ -82,15 +82,15 @@ class StyleGridTest extends PluginKernelTestBase {
     }
     // Ensure last column exists.
     $result = $this->xpath('//div[contains(@class, "views-col") and contains(@class, :columns) and starts-with(@style, :width)]', [':columns' => 'col-' . $columns, ':width' => 'width: ' . $width]);
-    $this->assertTrue(count($result), ucfirst($alignment) . " $columns column grid: last column exists and automatic width calculated correctly.");
+    $this->assertGreaterThan(0, count($result), ucfirst($alignment) . " $columns column grid: last column exists and automatic width calculated correctly.");
     // Ensure no extra columns were generated.
     $result = $this->xpath('//div[contains(@class, "views-col") and contains(@class, :columns)]', [':columns' => 'col-' . ($columns + 1)]);
-    $this->assertFalse(count($result), ucfirst($alignment) . " $columns column grid: no extraneous columns exist.");
+    $this->assertEmpty($result, ucfirst($alignment) . " $columns column grid: no extraneous columns exist.");
     // Ensure tokens are being replaced in custom row/column classes.
     $result = $this->xpath('//div[contains(@class, "views-col") and contains(@class, "name-John")]');
-    $this->assertTrue(count($result), ucfirst($alignment) . " $columns column grid: Token replacement verified in custom column classes.");
+    $this->assertGreaterThan(0, count($result), ucfirst($alignment) . " $columns column grid: Token replacement verified in custom column classes.");
     $result = $this->xpath('//div[contains(@class, "views-row") and contains(@class, "age-25")]');
-    $this->assertTrue(count($result), ucfirst($alignment) . " $columns column grid: Token replacement verified in custom row classes.");
+    $this->assertGreaterThan(0, count($result), ucfirst($alignment) . " $columns column grid: Token replacement verified in custom row classes.");
   }
 
 }
diff --git a/core/modules/views/tests/src/Kernel/QueryGroupByTest.php b/core/modules/views/tests/src/Kernel/QueryGroupByTest.php
index dbedd805e8a..c4805a890b4 100644
--- a/core/modules/views/tests/src/Kernel/QueryGroupByTest.php
+++ b/core/modules/views/tests/src/Kernel/QueryGroupByTest.php
@@ -187,8 +187,8 @@ class QueryGroupByTest extends ViewsKernelTestBase {
     $view = Views::getView('test_group_by_in_filters');
     $this->executeView($view);
 
-    $this->assertTrue(strpos($view->build_info['query'], 'GROUP BY'), 'Make sure that GROUP BY is in the query');
-    $this->assertTrue(strpos($view->build_info['query'], 'HAVING'), 'Make sure that HAVING is in the query');
+    $this->assertContains('GROUP BY', (string) $view->build_info['query'], 'Make sure that GROUP BY is in the query');
+    $this->assertContains('HAVING', (string) $view->build_info['query'], 'Make sure that HAVING is in the query');
   }
 
   /**
@@ -204,7 +204,7 @@ class QueryGroupByTest extends ViewsKernelTestBase {
     $view->displayHandlers->get('default')->options['fields']['name']['group_type'] = 'min';
     unset($view->displayHandlers->get('default')->options['fields']['id']['group_type']);
     $this->executeView($view);
-    $this->assertTrue(strpos($view->build_info['query'], 'GROUP BY entity_test.id'), 'GROUP BY field includes the base table name when grouping on the base field.');
+    $this->assertContains('GROUP BY entity_test.id', (string) $view->build_info['query'], 'GROUP BY field includes the base table name when grouping on the base field.');
   }
 
   /**
diff --git a/core/modules/views/tests/src/Kernel/RenderCacheIntegrationTest.php b/core/modules/views/tests/src/Kernel/RenderCacheIntegrationTest.php
index 02e90cd5020..3102bdd8d36 100644
--- a/core/modules/views/tests/src/Kernel/RenderCacheIntegrationTest.php
+++ b/core/modules/views/tests/src/Kernel/RenderCacheIntegrationTest.php
@@ -145,7 +145,7 @@ class RenderCacheIntegrationTest extends ViewsKernelTestBase {
     // @todo Static render arrays don't support different pages yet, see
     //   https://www.drupal.org/node/2500701.
     // $this->assertViewsCacheTagsFromStaticRenderArray($view, $tags_page_2, $do_assert_views_caches);
-    $this->assertTrue(strpos($build['#markup'], $random_name) !== FALSE);
+    $this->assertContains($random_name, (string) $build['#markup']);
     $view->destroy();
 
     $this->pass('Page 1');
@@ -155,7 +155,7 @@ class RenderCacheIntegrationTest extends ViewsKernelTestBase {
     $entities[1]->save();
     $build = $this->assertViewsCacheTags($view, $tags_page_1, $do_assert_views_caches, $tags_page_1);
     $this->assertViewsCacheTagsFromStaticRenderArray($view, $tags_page_1, $do_assert_views_caches);
-    $this->assertTrue(strpos($build['#markup'], $random_name) !== FALSE);
+    $this->assertContains($random_name, (string) $build['#markup']);
     $view->destroy();
 
     // Setup arguments to ensure that render caching also varies by them.
diff --git a/core/modules/views/tests/src/Kernel/ViewElementTest.php b/core/modules/views/tests/src/Kernel/ViewElementTest.php
index 2dbc31ca0a3..921fac70b16 100644
--- a/core/modules/views/tests/src/Kernel/ViewElementTest.php
+++ b/core/modules/views/tests/src/Kernel/ViewElementTest.php
@@ -33,7 +33,7 @@ class ViewElementTest extends ViewsKernelTestBase {
     $this->setRawContent($renderer->renderRoot($render));
 
     $xpath = $this->xpath('//div[@class="views-element-container"]');
-    $this->assertTrue($xpath, 'The view container has been found in the rendered output.');
+    $this->assertNotEmpty($xpath, 'The view container has been found in the rendered output.');
 
     // There should be 5 rows in the results.
     $xpath = $this->xpath('//div[@class="views-row"]');
@@ -86,7 +86,7 @@ class ViewElementTest extends ViewsKernelTestBase {
     serialize($render);
 
     $xpath = $this->xpath('//div[@class="views-element-container"]');
-    $this->assertTrue($xpath, 'The view container has been found in the rendered output.');
+    $this->assertNotEmpty($xpath, 'The view container has been found in the rendered output.');
 
     // There should be 5 rows in the results.
     $xpath = $this->xpath('//div[@class="views-row"]');
diff --git a/core/modules/views/tests/src/Kernel/ViewExecutableTest.php b/core/modules/views/tests/src/Kernel/ViewExecutableTest.php
index e59dc8defed..84d2504e25d 100644
--- a/core/modules/views/tests/src/Kernel/ViewExecutableTest.php
+++ b/core/modules/views/tests/src/Kernel/ViewExecutableTest.php
@@ -125,7 +125,7 @@ class ViewExecutableTest extends ViewsKernelTestBase {
       if ($type == 'relationship') {
         continue;
       }
-      $this->assertTrue(count($view->$type), new FormattableMarkup('Make sure a %type instance got instantiated.', ['%type' => $type]));
+      $this->assertGreaterThan(0, count($view->$type), new FormattableMarkup('Make sure a %type instance got instantiated.', ['%type' => $type]));
     }
 
     // initHandlers() should create display handlers automatically as well.
@@ -437,7 +437,7 @@ class ViewExecutableTest extends ViewsKernelTestBase {
       $match = function ($value) use ($display) {
         return strpos($value, $display->display['display_title']) !== FALSE;
       };
-      $this->assertTrue(array_filter($validate[$id], $match), new FormattableMarkup('Error message found for @id display', ['@id' => $id]));
+      $this->assertNotEmpty(array_filter($validate[$id], $match), new FormattableMarkup('Error message found for @id display', ['@id' => $id]));
       $count++;
     }
 
diff --git a/core/modules/views/tests/src/Kernel/ViewStorageTest.php b/core/modules/views/tests/src/Kernel/ViewStorageTest.php
index 917d1633eac..e764806e3d8 100644
--- a/core/modules/views/tests/src/Kernel/ViewStorageTest.php
+++ b/core/modules/views/tests/src/Kernel/ViewStorageTest.php
@@ -107,7 +107,7 @@ class ViewStorageTest extends ViewsKernelTestBase {
 
     // Make sure that loaded default views get a UUID.
     $view = Views::getView('test_view_storage');
-    $this->assertTrue($view->storage->uuid());
+    $this->assertNotEmpty($view->storage->uuid());
   }
 
   /**
diff --git a/core/modules/views_ui/tests/src/Functional/AnalyzeTest.php b/core/modules/views_ui/tests/src/Functional/AnalyzeTest.php
index ac2a8b13f22..2ad5adc5f27 100644
--- a/core/modules/views_ui/tests/src/Functional/AnalyzeTest.php
+++ b/core/modules/views_ui/tests/src/Functional/AnalyzeTest.php
@@ -2,8 +2,6 @@
 
 namespace Drupal\Tests\views_ui\Functional;
 
-use Drupal\Component\Render\FormattableMarkup;
-
 /**
  * Tests the views analyze system.
  *
@@ -44,8 +42,8 @@ class AnalyzeTest extends UITestBase {
     $this->assertSession()->titleEquals('View analysis | Drupal');
 
     foreach (['ok', 'warning', 'error'] as $type) {
-      $xpath = $this->xpath('//div[contains(@class, :class)]', [':class' => $type]);
-      $this->assertTrue(count($xpath), new FormattableMarkup('Analyse messages with @type found', ['@type' => $type]));
+      // Check that analyse messages with the expected type found.
+      $this->assertSession()->elementExists('css', 'div.' . $type);
     }
 
     // This redirects the user back to the main views edit page.
diff --git a/core/modules/views_ui/tests/src/Functional/CustomBooleanTest.php b/core/modules/views_ui/tests/src/Functional/CustomBooleanTest.php
index 5d4dcdea2f6..77d2e0b35ee 100644
--- a/core/modules/views_ui/tests/src/Functional/CustomBooleanTest.php
+++ b/core/modules/views_ui/tests/src/Functional/CustomBooleanTest.php
@@ -73,17 +73,17 @@ class CustomBooleanTest extends UITestBase {
       'plain' => [
         'true' => $custom_true,
         'false' => $custom_false,
-        'test' => 'assertTrue',
+        'test' => 'assertContains',
       ],
       'allowed tag' => [
         'true' => '<p>' . $custom_true . '</p>',
         'false' => '<p>' . $custom_false . '</p>',
-        'test' => 'assertTrue',
+        'test' => 'assertContains',
       ],
       'disallowed tag' => [
         'true' => '<script>' . $custom_true . '</script>',
         'false' => '<script>' . $custom_false . '</script>',
-        'test' => 'assertFalse',
+        'test' => 'assertNotContains',
       ],
     ];
 
@@ -102,8 +102,8 @@ class CustomBooleanTest extends UITestBase {
       $view = Views::getView('test_view');
       $output = $view->preview();
       $output = \Drupal::service('renderer')->renderRoot($output);
-      $this->{$values['test']}(strpos($output, $values['true']), new FormattableMarkup('Expected custom boolean TRUE value %value in output for %type', ['%value' => $values['true'], '%type' => $type]));
-      $this->{$values['test']}(strpos($output, $values['false']), new FormattableMarkup('Expected custom boolean FALSE value %value in output for %type', ['%value' => $values['false'], '%type' => $type]));
+      $this->{$values['test']}($values['true'], (string) $output, new FormattableMarkup('Expected custom boolean TRUE value %value in output for %type', ['%value' => $values['true'], '%type' => $type]));
+      $this->{$values['test']}($values['false'], (string) $output, new FormattableMarkup('Expected custom boolean FALSE value %value in output for %type', ['%value' => $values['false'], '%type' => $type]));
     }
   }
 
@@ -145,17 +145,17 @@ class CustomBooleanTest extends UITestBase {
       'plain' => [
         'true' => $custom_true,
         'false' => $custom_false,
-        'test' => 'assertTrue',
+        'test' => 'assertContains',
       ],
       'allowed tag' => [
         'true' => '<p>' . $custom_true . '</p>',
         'false' => '<p>' . $custom_false . '</p>',
-        'test' => 'assertTrue',
+        'test' => 'assertContains',
       ],
       'disallowed tag' => [
         'true' => '<script>' . $custom_true . '</script>',
         'false' => '<script>' . $custom_false . '</script>',
-        'test' => 'assertFalse',
+        'test' => 'assertNotContains',
       ],
     ];
 
@@ -174,8 +174,8 @@ class CustomBooleanTest extends UITestBase {
       $view = Views::getView('test_view');
       $output = $view->preview();
       $output = \Drupal::service('renderer')->renderRoot($output);
-      $this->{$values['test']}(strpos($output, $values['true']), new FormattableMarkup('Expected custom boolean TRUE value %value in output for %type', ['%value' => $values['true'], '%type' => $type]));
-      $this->{$values['test']}(strpos($output, $values['false']), new FormattableMarkup('Expected custom boolean FALSE value %value in output for %type', ['%value' => $values['false'], '%type' => $type]));
+      $this->{$values['test']}($values['true'], (string) $output, new FormattableMarkup('Expected custom boolean TRUE value %value in output for %type', ['%value' => $values['true'], '%type' => $type]));
+      $this->{$values['test']}($values['false'], (string) $output, new FormattableMarkup('Expected custom boolean FALSE value %value in output for %type', ['%value' => $values['false'], '%type' => $type]));
 
       // Assert that we are using the correct template.
       $this->assertContains('llama', (string) $output);
diff --git a/core/modules/views_ui/tests/src/Functional/DisplayCRUDTest.php b/core/modules/views_ui/tests/src/Functional/DisplayCRUDTest.php
index 23a355709a3..83e43f9987e 100644
--- a/core/modules/views_ui/tests/src/Functional/DisplayCRUDTest.php
+++ b/core/modules/views_ui/tests/src/Functional/DisplayCRUDTest.php
@@ -138,11 +138,11 @@ class DisplayCRUDTest extends UITestBase {
     $view->initDisplay();
 
     $page_2 = $view->displayHandlers->get('page_2');
-    $this->assertTrue($page_2, 'The new page display got saved.');
+    $this->assertNotEmpty($page_2, 'The new page display got saved.');
     $this->assertEqual($page_2->display['display_title'], 'Page');
     $this->assertEqual($page_2->display['display_options']['path'], $path);
     $block_1 = $view->displayHandlers->get('block_1');
-    $this->assertTrue($block_1, 'The new block display got saved.');
+    $this->assertNotEmpty($block_1, 'The new block display got saved.');
     $this->assertEqual($block_1->display['display_plugin'], 'block');
     $this->assertEqual($block_1->display['display_title'], 'Block', 'The new display title got generated as expected.');
     $this->assertFalse(isset($block_1->display['display_options']['path']));
diff --git a/core/modules/views_ui/tests/src/Functional/DisplayTest.php b/core/modules/views_ui/tests/src/Functional/DisplayTest.php
index 44d74a21859..d2b03327eb0 100644
--- a/core/modules/views_ui/tests/src/Functional/DisplayTest.php
+++ b/core/modules/views_ui/tests/src/Functional/DisplayTest.php
@@ -55,9 +55,9 @@ class DisplayTest extends UITestBase {
     $view = $this->randomView($view);
 
     $this->clickLink(t('Reorder displays'));
-    $this->assertTrue($this->xpath('//tr[@id="display-row-default"]'), 'Make sure the default display appears on the reorder listing');
-    $this->assertTrue($this->xpath('//tr[@id="display-row-page_1"]'), 'Make sure the page display appears on the reorder listing');
-    $this->assertTrue($this->xpath('//tr[@id="display-row-block_1"]'), 'Make sure the block display appears on the reorder listing');
+    $this->assertNotEmpty($this->xpath('//tr[@id="display-row-default"]'), 'Make sure the default display appears on the reorder listing');
+    $this->assertNotEmpty($this->xpath('//tr[@id="display-row-page_1"]'), 'Make sure the page display appears on the reorder listing');
+    $this->assertNotEmpty($this->xpath('//tr[@id="display-row-block_1"]'), 'Make sure the block display appears on the reorder listing');
 
     // Ensure the view displays are in the expected order in configuration.
     $expected_display_order = ['default', 'block_1', 'page_1'];
@@ -88,17 +88,17 @@ class DisplayTest extends UITestBase {
     $path_prefix = 'admin/structure/views/view/' . $view['id'] . '/edit';
 
     $this->drupalGet($path_prefix);
-    $this->assertFalse($this->xpath('//div[contains(@class, :class)]', [':class' => 'views-display-disabled']), 'Make sure the disabled display css class does not appear after initial adding of a view.');
+    $this->assertEmpty($this->xpath('//div[contains(@class, :class)]', [':class' => 'views-display-disabled']), 'Make sure the disabled display css class does not appear after initial adding of a view.');
 
     $this->assertFieldById('edit-displays-settings-settings-content-tab-content-details-top-actions-disable', NULL, 'Make sure the disable button is visible.');
     $this->assertNoFieldById('edit-displays-settings-settings-content-tab-content-details-top-actions-enable', NULL, 'Make sure the enable button is not visible.');
     $this->drupalPostForm(NULL, [], 'Disable Page');
-    $this->assertTrue($this->xpath('//div[contains(@class, :class)]', [':class' => 'views-display-disabled']), 'Make sure the disabled display css class appears once the display is marked as such.');
+    $this->assertNotEmpty($this->xpath('//div[contains(@class, :class)]', [':class' => 'views-display-disabled']), 'Make sure the disabled display css class appears once the display is marked as such.');
 
     $this->assertNoFieldById('edit-displays-settings-settings-content-tab-content-details-top-actions-disable', NULL, 'Make sure the disable button is not visible.');
     $this->assertFieldById('edit-displays-settings-settings-content-tab-content-details-top-actions-enable', NULL, 'Make sure the enable button is visible.');
     $this->drupalPostForm(NULL, [], 'Enable Page');
-    $this->assertFalse($this->xpath('//div[contains(@class, :class)]', [':class' => 'views-display-disabled']), 'Make sure the disabled display css class does not appears once the display is enabled again.');
+    $this->assertEmpty($this->xpath('//div[contains(@class, :class)]', [':class' => 'views-display-disabled']), 'Make sure the disabled display css class does not appears once the display is enabled again.');
   }
 
   /**
@@ -192,14 +192,14 @@ class DisplayTest extends UITestBase {
     // The view should initially have the enabled class on its form wrapper.
     $this->drupalGet('admin/structure/views/view/' . $id);
     $elements = $this->xpath('//div[contains(@class, :edit) and contains(@class, :status)]', [':edit' => 'views-edit-view', ':status' => 'enabled']);
-    $this->assertTrue($elements, 'The enabled class was found on the form wrapper');
+    $this->assertNotEmpty($elements, 'The enabled class was found on the form wrapper');
 
     $view = Views::getView($id);
     $view->storage->disable()->save();
 
     $this->drupalGet('admin/structure/views/view/' . $id);
     $elements = $this->xpath('//div[contains(@class, :edit) and contains(@class, :status)]', [':edit' => 'views-edit-view', ':status' => 'disabled']);
-    $this->assertTrue($elements, 'The disabled class was found on the form wrapper.');
+    $this->assertNotEmpty($elements, 'The disabled class was found on the form wrapper.');
   }
 
   /**
diff --git a/core/modules/views_ui/tests/src/Functional/PreviewTest.php b/core/modules/views_ui/tests/src/Functional/PreviewTest.php
index a082c89231c..f254097f1f3 100644
--- a/core/modules/views_ui/tests/src/Functional/PreviewTest.php
+++ b/core/modules/views_ui/tests/src/Functional/PreviewTest.php
@@ -87,7 +87,7 @@ class PreviewTest extends UITestBase {
     $this->clickLink(t('Feed'));
     $this->drupalPostForm(NULL, [], t('Update preview'));
     $result = $this->xpath('//div[@id="views-live-preview"]/pre');
-    $this->assertTrue(strpos($result[0]->getText(), '<title>' . $view['page[title]'] . '</title>'), 'The Feed RSS preview was rendered.');
+    $this->assertContains('<title>' . $view['page[title]'] . '</title>', $result[0]->getText(), 'The Feed RSS preview was rendered.');
 
     // Test the non-default UI display options.
     // Statistics only, no query.
diff --git a/core/modules/views_ui/tests/src/Functional/UITestBase.php b/core/modules/views_ui/tests/src/Functional/UITestBase.php
index db857737141..7cbb312ff6f 100644
--- a/core/modules/views_ui/tests/src/Functional/UITestBase.php
+++ b/core/modules/views_ui/tests/src/Functional/UITestBase.php
@@ -81,7 +81,7 @@ abstract class UITestBase extends ViewTestBase {
       $result = $this->drupalGet($url, $options);
       $this->assertSession()->statusCodeEquals(200);
       $this->assertEquals('application/json', $this->getSession()->getResponseHeader('Content-Type'));
-      $this->assertTrue(json_decode($result), 'Ensure that the AJAX request returned valid content.');
+      $this->assertNotEmpty(json_decode($result), 'Ensure that the AJAX request returned valid content.');
     }
 
     return parent::drupalGet($path, $options, $headers);
diff --git a/core/modules/views_ui/tests/src/FunctionalJavascript/PreviewTest.php b/core/modules/views_ui/tests/src/FunctionalJavascript/PreviewTest.php
index ae33591b102..d426bc10361 100644
--- a/core/modules/views_ui/tests/src/FunctionalJavascript/PreviewTest.php
+++ b/core/modules/views_ui/tests/src/FunctionalJavascript/PreviewTest.php
@@ -140,19 +140,19 @@ class PreviewTest extends WebDriverTestBase {
     // We expect to find 5 elements: current page == 1, links to pages 2 and
     // and 3, links to 'next >' and 'last >>' pages.
     $this->assertClass($elements[0], 'is-active', 'Element for current page has .is-active class.');
-    $this->assertTrue($elements[0]->find('css', 'a'), 'Element for current page has link.');
+    $this->assertNotEmpty($elements[0]->find('css', 'a'), 'Element for current page has link.');
 
     $this->assertClass($elements[1], 'pager__item', 'Element for page 2 has .pager__item class.');
-    $this->assertTrue($elements[1]->find('css', 'a'), 'Link to page 2 found.');
+    $this->assertNotEmpty($elements[1]->find('css', 'a'), 'Link to page 2 found.');
 
     $this->assertClass($elements[2], 'pager__item', 'Element for page 3 has .pager__item class.');
-    $this->assertTrue($elements[2]->find('css', 'a'), 'Link to page 3 found.');
+    $this->assertNotEmpty($elements[2]->find('css', 'a'), 'Link to page 3 found.');
 
     $this->assertClass($elements[3], 'pager__item--next', 'Element for next page has .pager__item--next class.');
-    $this->assertTrue($elements[3]->find('css', 'a'), 'Link to next page found.');
+    $this->assertNotEmpty($elements[3]->find('css', 'a'), 'Link to next page found.');
 
     $this->assertClass($elements[4], 'pager__item--last', 'Element for last page has .pager__item--last class.');
-    $this->assertTrue($elements[4]->find('css', 'a'), 'Link to last page found.');
+    $this->assertNotEmpty($elements[4]->find('css', 'a'), 'Link to last page found.');
 
     // Navigate to next page.
     $elements = $this->xpath('//li[contains(@class, :class)]/a', [':class' => 'pager__item--next']);
@@ -167,25 +167,25 @@ class PreviewTest extends WebDriverTestBase {
     // pages, link to page 1, current page == 2, link to page 3 and links
     // to 'next >' and 'last >>' pages.
     $this->assertClass($elements[0], 'pager__item--first', 'Element for first page has .pager__item--first class.');
-    $this->assertTrue($elements[0]->find('css', 'a'), 'Link to first page found.');
+    $this->assertNotEmpty($elements[0]->find('css', 'a'), 'Link to first page found.');
 
     $this->assertClass($elements[1], 'pager__item--previous', 'Element for previous page has .pager__item--previous class.');
-    $this->assertTrue($elements[1]->find('css', 'a'), 'Link to previous page found.');
+    $this->assertNotEmpty($elements[1]->find('css', 'a'), 'Link to previous page found.');
 
     $this->assertClass($elements[2], 'pager__item', 'Element for page 1 has .pager__item class.');
-    $this->assertTrue($elements[2]->find('css', 'a'), 'Link to page 1 found.');
+    $this->assertNotEmpty($elements[2]->find('css', 'a'), 'Link to page 1 found.');
 
     $this->assertClass($elements[3], 'is-active', 'Element for current page has .is-active class.');
-    $this->assertTrue($elements[3]->find('css', 'a'), 'Element for current page has link.');
+    $this->assertNotEmpty($elements[3]->find('css', 'a'), 'Element for current page has link.');
 
     $this->assertClass($elements[4], 'pager__item', 'Element for page 3 has .pager__item class.');
-    $this->assertTrue($elements[4]->find('css', 'a'), 'Link to page 3 found.');
+    $this->assertNotEmpty($elements[4]->find('css', 'a'), 'Link to page 3 found.');
 
     $this->assertClass($elements[5], 'pager__item--next', 'Element for next page has .pager__item--next class.');
-    $this->assertTrue($elements[5]->find('css', 'a'), 'Link to next page found.');
+    $this->assertNotEmpty($elements[5]->find('css', 'a'), 'Link to next page found.');
 
     $this->assertClass($elements[6], 'pager__item--last', 'Element for last page has .pager__item--last class.');
-    $this->assertTrue($elements[6]->find('css', 'a'), 'Link to last page found.');
+    $this->assertNotEmpty($elements[6]->find('css', 'a'), 'Link to last page found.');
 
     // Test Mini Pager.
     $this->getPreviewAJAX('test_mini_pager_ajax', 'default', 3);
@@ -200,7 +200,7 @@ class PreviewTest extends WebDriverTestBase {
     $this->assertClass($elements[0], 'is-active', 'Element for current page has .is-active class.');
 
     $this->assertClass($elements[1], 'pager__item--next', 'Element for next page has .pager__item--next class.');
-    $this->assertTrue($elements[1]->find('css', 'a'), 'Link to next page found.');
+    $this->assertNotEmpty($elements[1]->find('css', 'a'), 'Link to next page found.');
 
     // Navigate to next page.
     $elements = $this->xpath('//li[contains(@class, :class)]/a', [':class' => 'pager__item--next']);
@@ -214,13 +214,13 @@ class PreviewTest extends WebDriverTestBase {
     // We expect to find 3 elements: previous page with a link, current
     // page with no link, and next page with a link.
     $this->assertClass($elements[0], 'pager__item--previous', 'Element for previous page has .pager__item--previous class.');
-    $this->assertTrue($elements[0]->find('css', 'a'), 'Link to previous page found.');
+    $this->assertNotEmpty($elements[0]->find('css', 'a'), 'Link to previous page found.');
 
     $this->assertClass($elements[1], 'is-active', 'Element for current page has .is-active class.');
     $this->assertEmpty($elements[1]->find('css', 'a'), 'Element for current page has no link.');
 
     $this->assertClass($elements[2], 'pager__item--next', 'Element for next page has .pager__item--next class.');
-    $this->assertTrue($elements[2]->find('css', 'a'), 'Link to next page found.');
+    $this->assertNotEmpty($elements[2]->find('css', 'a'), 'Link to next page found.');
   }
 
   /**
diff --git a/core/modules/workspaces/tests/src/Functional/WorkspaceCacheContextTest.php b/core/modules/workspaces/tests/src/Functional/WorkspaceCacheContextTest.php
index 517e6b8d710..aabffbb7132 100644
--- a/core/modules/workspaces/tests/src/Functional/WorkspaceCacheContextTest.php
+++ b/core/modules/workspaces/tests/src/Functional/WorkspaceCacheContextTest.php
@@ -62,7 +62,7 @@ class WorkspaceCacheContextTest extends BrowserTestBase {
     // Test that a cache entry is created.
     $cid = implode(':', $cid_parts);
     $bin = $build['#cache']['bin'];
-    $this->assertTrue($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
+    $this->assertInstanceOf(\stdClass::class, $this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
 
     // Switch to the 'stage' workspace and check that the correct workspace
     // cache context is used.
@@ -88,7 +88,7 @@ class WorkspaceCacheContextTest extends BrowserTestBase {
     // Test that a cache entry is created.
     $cid = implode(':', $cid_parts);
     $bin = $build['#cache']['bin'];
-    $this->assertTrue($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
+    $this->assertInstanceOf(\stdClass::class, $this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
   }
 
 }
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/Core/Form/FormGroupingElementsTest.php b/core/tests/Drupal/FunctionalJavascriptTests/Core/Form/FormGroupingElementsTest.php
index 20acd677de5..9c0bbe37073 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/Core/Form/FormGroupingElementsTest.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/Core/Form/FormGroupingElementsTest.php
@@ -131,8 +131,8 @@ class FormGroupingElementsTest extends WebDriverTestBase {
     $summary = $page->find('css', '#edit-meta > summary');
 
     // Assert that both aria-expanded and aria-pressed are true.
-    $this->assertTrue($summary->getAttribute('aria-expanded'));
-    $this->assertTrue($summary->getAttribute('aria-pressed'));
+    $this->assertEquals('true', $summary->getAttribute('aria-expanded'));
+    $this->assertEquals('true', $summary->getAttribute('aria-pressed'));
   }
 
 }
diff --git a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
index 95a84babaf7..fecbb0ca4e6 100644
--- a/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -146,7 +146,7 @@ class BrowserTestBaseTest extends BrowserTestBase {
 
     // Test drupalPostForm() with no-html response.
     $values = Json::decode($this->drupalPostForm('form_test/form-state-values-clean', [], t('Submit')));
-    $this->assertTrue(1000, $values['beer']);
+    $this->assertSame(1000, $values['beer']);
 
     // Test drupalPostForm() with form by HTML id.
     $this->drupalCreateContentType(['type' => 'page']);
diff --git a/core/tests/Drupal/FunctionalTests/BrowserTestBaseUserAgentTest.php b/core/tests/Drupal/FunctionalTests/BrowserTestBaseUserAgentTest.php
index ac6d7606352..28f9c1e5675 100644
--- a/core/tests/Drupal/FunctionalTests/BrowserTestBaseUserAgentTest.php
+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseUserAgentTest.php
@@ -32,7 +32,7 @@ class BrowserTestBaseUserAgentTest extends BrowserTestBase {
     $http_path = $system_path . '/tests/http.php/user/login';
     $https_path = $system_path . '/tests/https.php/user/login';
     // Generate a valid simpletest User-Agent to pass validation.
-    $this->assertTrue(preg_match('/test\d+/', $this->databasePrefix, $matches), 'Database prefix contains test prefix.');
+    $this->assertNotFalse(preg_match('/test\d+/', $this->databasePrefix, $matches), 'Database prefix contains test prefix.');
     $this->agent = drupal_generate_test_ua($matches[0]);
 
     // Test pages only available for testing.
diff --git a/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php b/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php
index 370b548be5e..8ae5d36c6ef 100644
--- a/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php
@@ -418,7 +418,7 @@ class AttachedAssetsTest extends KernelTestBase {
     $js = $this->assetResolver->getJsAssets($assets, FALSE)[1];
     $js_render_array = \Drupal::service('asset.js.collection_renderer')->render($js);
     $rendered_js = $this->renderer->renderPlain($js_render_array);
-    $this->assertTrue(strpos($rendered_js, 'core/assets/vendor/jquery-form/jquery.form.min.js'), 'Altered library dependencies are added to the page.');
+    $this->assertContains('core/assets/vendor/jquery-form/jquery.form.min.js', (string) $rendered_js, 'Altered library dependencies are added to the page.');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php b/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
index a77adfcdc14..2b7a5ff3ae4 100644
--- a/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
@@ -37,7 +37,7 @@ class LibraryDiscoveryIntegrationTest extends KernelTestBase {
     // Activate test_theme and verify that the library 'kitten' is added using
     // hook_library_info_alter().
     $this->activateTheme('test_theme');
-    $this->assertTrue($this->libraryDiscovery->getLibraryByName('test_theme', 'kitten'));
+    $this->assertNotEmpty($this->libraryDiscovery->getLibraryByName('test_theme', 'kitten'));
 
     // Now make classy the active theme and assert that library is not added.
     $this->activateTheme('classy');
@@ -57,7 +57,7 @@ class LibraryDiscoveryIntegrationTest extends KernelTestBase {
     $this->assertAssetInLibrary('core/themes/classy/css/components/dialog.css', 'classy', 'dialog', 'css');
 
     // Confirmatory assert on core library to be removed.
-    $this->assertTrue($this->libraryDiscovery->getLibraryByName('core', 'drupal.progress'), 'Confirmatory test on "core/drupal.progress"');
+    $this->assertNotEmpty($this->libraryDiscovery->getLibraryByName('core', 'drupal.progress'), 'Confirmatory test on "core/drupal.progress"');
 
     // Activate test theme that defines libraries overrides.
     $this->activateTheme('test_theme');
diff --git a/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php b/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php
index 865205eb2e5..912fddf71a7 100644
--- a/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php
@@ -41,7 +41,7 @@ class DatabaseBackendTagTest extends KernelTestBase {
     foreach ($bins as $bin) {
       $bin = \Drupal::cache($bin);
       $bin->set('test', 'value', Cache::PERMANENT, $tags);
-      $this->assertTrue($bin->get('test'), 'Cache item was set in bin.');
+      $this->assertNotEmpty($bin->get('test'), 'Cache item was set in bin.');
     }
 
     $connection = Database::getConnection();
diff --git a/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php b/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php
index ce5b28c91c1..1cbc64b6073 100644
--- a/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php
@@ -470,7 +470,7 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
     $this->assertSame(FALSE, $backend->get('test21'), "Cache id test21 does not exist.");
 
     // Calling deleteMultiple() with an empty array should not cause an error.
-    $this->assertFalse($backend->deleteMultiple([]));
+    $this->assertNull($backend->deleteMultiple([]));
   }
 
   /**
@@ -489,7 +489,7 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
 
     $this->assertFalse($backend_a->get('test1'), 'First key has been deleted.');
     $this->assertFalse($backend_a->get('test2'), 'Second key has been deleted.');
-    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
+    $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
   }
 
   /**
@@ -522,7 +522,7 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
 
     // Calling invalidateMultiple() with an empty array should not cause an
     // error.
-    $this->assertFalse($backend->invalidateMultiple([]));
+    $this->assertNull($backend->invalidateMultiple([]));
   }
 
   /**
@@ -567,7 +567,7 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
     $bins = ['path', 'bootstrap', 'page'];
     foreach ($bins as $bin) {
       $this->getCacheBackend($bin)->set('test', $this->defaultValue, Cache::PERMANENT, $tags);
-      $this->assertTrue($this->getCacheBackend($bin)->get('test'), 'Cache item was set in bin.');
+      $this->assertNotEmpty($this->getCacheBackend($bin)->get('test'), 'Cache item was set in bin.');
     }
 
     Cache::invalidateTags(['test_tag:2']);
@@ -579,7 +579,7 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
     // Test that the cache entry with a matching tag has been invalidated.
     $this->assertFalse($this->getCacheBackend($bin)->get('test_cid_invalidate2'), 'Cache items matching tag were invalidated.');
     // Test that the cache entry with without a matching tag still exists.
-    $this->assertTrue($this->getCacheBackend($bin)->get('test_cid_invalidate1'), 'Cache items not matching tag were not invalidated.');
+    $this->assertNotEmpty($this->getCacheBackend($bin)->get('test_cid_invalidate1'), 'Cache items not matching tag were not invalidated.');
   }
 
   /**
@@ -598,9 +598,9 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
 
     $this->assertFalse($backend_a->get('test1'), 'First key has been invalidated.');
     $this->assertFalse($backend_a->get('test2'), 'Second key has been invalidated.');
-    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
-    $this->assertTrue($backend_a->get('test1', TRUE), 'First key has not been deleted.');
-    $this->assertTrue($backend_a->get('test2', TRUE), 'Second key has not been deleted.');
+    $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
+    $this->assertNotEmpty($backend_a->get('test1', TRUE), 'First key has not been deleted.');
+    $this->assertNotEmpty($backend_a->get('test2', TRUE), 'Second key has not been deleted.');
   }
 
   /**
@@ -619,7 +619,7 @@ abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
 
     $this->assertFalse($backend_a->get('test1'), 'First key has been deleted.');
     $this->assertFalse($backend_a->get('test2', TRUE), 'Second key has been deleted.');
-    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
+    $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php b/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php
index f5f8456848f..09aafb35645 100644
--- a/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php
@@ -163,21 +163,21 @@ class DbDumpTest extends KernelTestBase {
 
     // Tables that are schema-only should not have data exported.
     $pattern = preg_quote("\$connection->insert('sessions')");
-    $this->assertFalse(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'Tables defined as schema-only do not have data exported to the script.');
+    $this->assertNotRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'Tables defined as schema-only do not have data exported to the script.');
 
     // Table data is exported.
     $pattern = preg_quote("\$connection->insert('config')");
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'Table data is properly exported to the script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'Table data is properly exported to the script.');
 
     // The test data are in the dump (serialized).
     $pattern = preg_quote(serialize($this->data));
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'Generated data is found in the exported script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'Generated data is found in the exported script.');
 
     // Check that the user account name and email address was properly escaped.
     $pattern = preg_quote('"q\'uote\$dollar@example.com"');
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'The user account email address was properly escaped in the exported script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'The user account email address was properly escaped in the exported script.');
     $pattern = preg_quote('\'$dollar\'');
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'The user account name was properly escaped in the exported script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'The user account name was properly escaped in the exported script.');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php
index fb310bd32de..63e3b8fd01d 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php
@@ -220,8 +220,8 @@ class ConfigDependencyTest extends EntityKernelTestBase {
     // Test that doing a config uninstall of the node module deletes entity2
     // since it is dependent on entity1 which is dependent on the node module.
     $config_manager->uninstall('module', 'node');
-    $this->assertFalse($storage->load('entity1'), 'Entity 1 deleted');
-    $this->assertFalse($storage->load('entity2'), 'Entity 2 deleted');
+    $this->assertNull($storage->load('entity1'), 'Entity 1 deleted');
+    $this->assertNull($storage->load('entity2'), 'Entity 2 deleted');
   }
 
   /**
@@ -359,14 +359,14 @@ class ConfigDependencyTest extends EntityKernelTestBase {
     $config_manager->uninstall('module', 'node');
 
     // Test that expected actions have been performed.
-    $this->assertFalse($storage->load($entity_1->id()), 'Entity 1 deleted');
+    $this->assertNull($storage->load($entity_1->id()), 'Entity 1 deleted');
     $entity_2 = $storage->load($entity_2->id());
-    $this->assertTrue($entity_2, 'Entity 2 not deleted');
+    $this->assertNotEmpty($entity_2, 'Entity 2 not deleted');
     $this->assertEqual($entity_2->calculateDependencies()->getDependencies()['config'], [], 'Entity 2 dependencies updated to remove dependency on entity 1.');
     $entity_3 = $storage->load($entity_3->id());
-    $this->assertTrue($entity_3, 'Entity 3 not deleted');
+    $this->assertNotEmpty($entity_3, 'Entity 3 not deleted');
     $this->assertEqual($entity_3->calculateDependencies()->getDependencies()['config'], [$entity_2->getConfigDependencyName()], 'Entity 3 still depends on entity 2.');
-    $this->assertFalse($storage->load($entity_4->id()), 'Entity 4 deleted');
+    $this->assertNull($storage->load($entity_4->id()), 'Entity 4 deleted');
   }
 
   /**
@@ -473,16 +473,16 @@ class ConfigDependencyTest extends EntityKernelTestBase {
 
     // Test that expected actions have been performed.
     $entity_1 = $storage->load($entity_1->id());
-    $this->assertTrue($entity_1, 'Entity 1 not deleted');
+    $this->assertNotEmpty($entity_1, 'Entity 1 not deleted');
     $this->assertSame($entity_1->getThirdPartySettings('node'), [], 'Entity 1 third party settings updated.');
     $entity_2 = $storage->load($entity_2->id());
-    $this->assertTrue($entity_2, 'Entity 2 not deleted');
+    $this->assertNotEmpty($entity_2, 'Entity 2 not deleted');
     $this->assertSame($entity_2->getThirdPartySettings('node'), [], 'Entity 2 third party settings updated.');
     $this->assertSame($entity_2->calculateDependencies()->getDependencies()['config'], [$entity_1->getConfigDependencyName()], 'Entity 2 still depends on entity 1.');
     $entity_3 = $storage->load($entity_3->id());
-    $this->assertTrue($entity_3, 'Entity 3 not deleted');
+    $this->assertNotEmpty($entity_3, 'Entity 3 not deleted');
     $this->assertSame($entity_3->calculateDependencies()->getDependencies()['config'], [$entity_2->getConfigDependencyName()], 'Entity 3 still depends on entity 2.');
-    $this->assertFalse($storage->load($entity_4->id()), 'Entity 4 deleted');
+    $this->assertNull($storage->load($entity_4->id()), 'Entity 4 deleted');
   }
 
   /**
@@ -522,8 +522,8 @@ class ConfigDependencyTest extends EntityKernelTestBase {
     // Test that doing a delete of entity1 deletes entity2 since it is dependent
     // on entity1.
     $entity1->delete();
-    $this->assertFalse($storage->load('entity1'), 'Entity 1 deleted');
-    $this->assertFalse($storage->load('entity2'), 'Entity 2 deleted');
+    $this->assertNull($storage->load('entity1'), 'Entity 1 deleted');
+    $this->assertNull($storage->load('entity2'), 'Entity 2 deleted');
 
     // Set a more complicated test where dependencies will be fixed.
     \Drupal::state()->set('config_test.fix_dependencies', [$entity1->getConfigDependencyName()]);
@@ -576,12 +576,12 @@ class ConfigDependencyTest extends EntityKernelTestBase {
     $entity1->delete();
 
     // Test that expected actions have been performed.
-    $this->assertFalse($storage->load('entity1'), 'Entity 1 deleted');
+    $this->assertNull($storage->load('entity1'), 'Entity 1 deleted');
     $entity2 = $storage->load('entity2');
-    $this->assertTrue($entity2, 'Entity 2 not deleted');
+    $this->assertNotEmpty($entity2, 'Entity 2 not deleted');
     $this->assertEqual($entity2->calculateDependencies()->getDependencies()['config'], [], 'Entity 2 dependencies updated to remove dependency on Entity1.');
     $entity3 = $storage->load('entity3');
-    $this->assertTrue($entity3, 'Entity 3 not deleted');
+    $this->assertNotEmpty($entity3, 'Entity 3 not deleted');
     $this->assertEqual($entity3->calculateDependencies()->getDependencies()['config'], [$entity2->getConfigDependencyName()], 'Entity 3 still depends on Entity 2.');
   }
 
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php
index 822ad07d301..818be6ecca4 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php
@@ -56,7 +56,7 @@ class ConfigFileContentTest extends KernelTestBase {
 
     // Verify a configuration object is returned.
     $this->assertEqual($config->getName(), $name);
-    $this->assertTrue($config, 'Config object created.');
+    $this->assertNotEmpty($config, 'Config object created.');
 
     // Verify the configuration object is empty.
     $this->assertEqual($config->get(), [], 'New config object is empty.');
@@ -93,12 +93,12 @@ class ConfigFileContentTest extends KernelTestBase {
 
     // Verify the database entry exists.
     $data = $storage->read($name);
-    $this->assertTrue($data);
+    $this->assertNotEmpty($data);
 
     // Read top level value.
     $config = $this->config($name);
     $this->assertEqual($config->getName(), $name);
-    $this->assertTrue($config, 'Config object created.');
+    $this->assertNotEmpty($config, 'Config object created.');
     $this->assertEqual($config->get($key), 'bar', 'Top level configuration value found.');
 
     // Read nested value.
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php
index 9bb2cd3a5cc..a976edb1cb8 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php
@@ -118,7 +118,7 @@ class ConfigImporterTest extends KernelTestBase {
       $expected = static::FAIL_MESSAGE . PHP_EOL . 'Site UUID in source storage does not match the target storage.';
       $this->assertEquals($expected, $actual_message);
       foreach ($expected_error_log as $log_row) {
-        $this->assertTrue(preg_match("/$log_row/", $actual_message));
+        $this->assertRegExp("/$log_row/", $actual_message);
       }
     }
   }
@@ -376,7 +376,7 @@ class ConfigImporterTest extends KernelTestBase {
 
     // The deletee was deleted in
     // \Drupal\config_test\Entity\ConfigTest::postSave().
-    $this->assertFalse($entity_storage->load('deletee'));
+    $this->assertNull($entity_storage->load('deletee'));
 
     $other = $entity_storage->load('other');
     $this->assertEqual($other->id(), 'other');
@@ -432,8 +432,8 @@ class ConfigImporterTest extends KernelTestBase {
     // Both entities are deleted. ConfigTest::postSave() causes updates of the
     // deleter entity to delete the deletee entity. Since the deleter depends on
     // the deletee, removing the deletee causes the deleter to be removed.
-    $this->assertFalse($entity_storage->load('deleter'));
-    $this->assertFalse($entity_storage->load('deletee'));
+    $this->assertNull($entity_storage->load('deleter'));
+    $this->assertNull($entity_storage->load('deletee'));
     $logs = $this->configImporter->getErrors();
     $this->assertEqual(count($logs), 0);
   }
@@ -471,8 +471,8 @@ class ConfigImporterTest extends KernelTestBase {
     $this->configImporter->reset()->import();
 
     $entity_storage = \Drupal::entityTypeManager()->getStorage('config_test');
-    $this->assertFalse($entity_storage->load('deleter'));
-    $this->assertFalse($entity_storage->load('deletee'));
+    $this->assertNull($entity_storage->load('deleter'));
+    $this->assertNull($entity_storage->load('deletee'));
     // The deletee entity does not exist as the delete worked and although the
     // delete occurred in \Drupal\config_test\Entity\ConfigTest::postDelete()
     // this does not matter.
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php
index c5cee572036..785b9f959dc 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php
@@ -225,7 +225,7 @@ class ConfigInstallTest extends KernelTestBase {
     $this->installModules(['config_other_module_config_test']);
     $this->installModules(['config_install_dependency_test']);
     $entity = \Drupal::entityTypeManager()->getStorage('config_test')->load('other_module_test_with_dependency');
-    $this->assertTrue($entity, 'The config_test.dynamic.other_module_test_with_dependency configuration has been created during install.');
+    $this->assertNotEmpty($entity, 'The config_test.dynamic.other_module_test_with_dependency configuration has been created during install.');
     // Ensure that dependencies can be added during module installation by
     // hooks.
     $this->assertSame('config_install_dependency_test', $entity->getDependencies()['module'][0]);
diff --git a/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php b/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
index 0a649497f9f..b004b63b35b 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
@@ -58,7 +58,7 @@ class QueryTest extends DatabaseTestBase {
       ->countQuery()
       ->execute()
       ->fetchField();
-    $this->assertFalse($result, 'SQL injection attempt did not result in a row being inserted in the database table.');
+    $this->assertEquals(0, $result, 'SQL injection attempt did not result in a row being inserted in the database table.');
   }
 
   /**
@@ -95,7 +95,7 @@ class QueryTest extends DatabaseTestBase {
       ->countQuery()
       ->execute()
       ->fetchField();
-    $this->assertFalse($result, 'SQL injection attempt did not result in a row being inserted in the database table.');
+    $this->assertEquals(0, $result, 'SQL injection attempt did not result in a row being inserted in the database table.');
 
     // Attempt SQLi via union query with no unsafe characters.
     $this->enableModules(['user']);
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
index 4bc6b39e89b..6956af2e819 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
@@ -203,7 +203,7 @@ class ContentEntityChangedTest extends EntityKernelTestBase {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_de, '=', 'en')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'There\'s no original entity stored having the changed time of the German translation.'
     );
@@ -219,7 +219,7 @@ class ContentEntityChangedTest extends EntityKernelTestBase {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_de)->condition('default_langcode', '1')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'There\'s no entity stored using the default language having the changed time of the German translation.'
     );
@@ -243,7 +243,7 @@ class ContentEntityChangedTest extends EntityKernelTestBase {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_en, '=', 'de')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'There\'s no German translation stored having the changed time of the original language.'
     );
@@ -275,7 +275,7 @@ class ContentEntityChangedTest extends EntityKernelTestBase {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_en, '>')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'Entity query can access changed time regardless of translation.'
     );
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php
index fbbd3a68d56..d2c95cfe8c8 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\KernelTests\Core\Entity;
 
 use Drupal\Component\Render\FormattableMarkup;
+use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityStorageException;
 use Drupal\Core\Entity\RevisionLogInterface;
@@ -619,12 +620,12 @@ class EntityFieldTest extends EntityKernelTestBase {
   public function testDataTypes() {
     $types = \Drupal::typedDataManager()->getDefinitions();
     foreach (entity_test_entity_types() as $entity_type) {
-      $this->assertTrue($types['entity:' . $entity_type]['class'], 'Entity data type registered.');
+      $this->assertNotEmpty($types['entity:' . $entity_type]['class'], 'Entity data type registered.');
     }
     // Check bundle types are provided as well.
     entity_test_create_bundle('bundle');
     $types = \Drupal::typedDataManager()->getDefinitions();
-    $this->assertTrue($types['entity:entity_test:bundle']['class'], 'Entity bundle data type registered.');
+    $this->assertNotEmpty($types['entity:entity_test:bundle']['class'], 'Entity bundle data type registered.');
   }
 
   /**
@@ -937,12 +938,12 @@ class EntityFieldTest extends EntityKernelTestBase {
     $this->assertSame($entity_id, $entity->id());
     $storage->save($entity);
     $entity = $storage->loadUnchanged($entity->id());
-    $this->assertTrue($entity);
+    $this->assertInstanceOf(ContentEntityInterface::class, $entity);
 
     // Check that an explicitly-assigned ID is preserved on update.
     $storage->save($entity);
     $entity = $storage->loadUnchanged($entity->id());
-    $this->assertTrue($entity);
+    $this->assertInstanceOf(ContentEntityInterface::class, $entity);
 
     // Check that an ID cannot be explicitly assigned on update.
     $this->expectException(EntityStorageException::class);
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php
index a6819f01905..21ac9915c44 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php
@@ -528,7 +528,7 @@ class EntityQueryTest extends EntityKernelTestBase {
       ->exists("$field_name.color")
       ->count()
       ->execute();
-    $this->assertFalse($count);
+    $this->assertEquals(0, $count);
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
index aa2a999f2db..24c256ee1c6 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
@@ -52,7 +52,7 @@ class EntityTranslationTest extends EntityLanguageTestBase {
       ]);
 
     $this->assertEqual($entity->language()->getId(), LanguageInterface::LANGCODE_NOT_SPECIFIED, new FormattableMarkup('%entity_type: Entity language not specified.', ['%entity_type' => $entity_type]));
-    $this->assertFalse($entity->getTranslationLanguages(FALSE), new FormattableMarkup('%entity_type: No translations are available', ['%entity_type' => $entity_type]));
+    $this->assertEmpty($entity->getTranslationLanguages(FALSE), new FormattableMarkup('%entity_type: No translations are available', ['%entity_type' => $entity_type]));
 
     // Set the value in default language.
     $entity->set($this->fieldName, [0 => ['value' => 'default value']]);
@@ -77,7 +77,7 @@ class EntityTranslationTest extends EntityLanguageTestBase {
     $entity->{$langcode_key}->value = $default_langcode;
     $entity->{$this->fieldName} = [];
     $this->assertEqual($entity->language(), \Drupal::languageManager()->getLanguage($this->langcodes[0]), new FormattableMarkup('%entity_type: Entity language retrieved.', ['%entity_type' => $entity_type]));
-    $this->assertFalse($entity->getTranslationLanguages(FALSE), new FormattableMarkup('%entity_type: No translations are available', ['%entity_type' => $entity_type]));
+    $this->assertEmpty($entity->getTranslationLanguages(FALSE), new FormattableMarkup('%entity_type: No translations are available', ['%entity_type' => $entity_type]));
 
     // Set the value in default language.
     $entity->set($this->fieldName, [0 => ['value' => 'default value']]);
@@ -336,7 +336,7 @@ class EntityTranslationTest extends EntityLanguageTestBase {
 
     $entity->save();
     $hooks = $this->getHooksInfo();
-    $this->assertFalse($hooks, 'No entity translation hooks are fired when creating an entity.');
+    $this->assertEmpty($hooks, 'No entity translation hooks are fired when creating an entity.');
 
     // Verify that we obtain the entity object itself when we attempt to
     // retrieve a translation referring to it.
@@ -508,7 +508,7 @@ class EntityTranslationTest extends EntityLanguageTestBase {
     $this->assertTrue(isset($hooks[$entity_type . '_translation_create']), 'The entity-type-specific entity translation creation hook is run when adding and removing a translation without storing it.');
     unset($hooks[$entity_type . '_translation_create']);
 
-    $this->assertFalse($hooks, 'No other hooks beyond the entity translation creation hooks are run when adding and removing a translation without storing it.');
+    $this->assertEmpty($hooks, 'No other hooks beyond the entity translation creation hooks are run when adding and removing a translation without storing it.');
 
     // Check that hooks are fired only when actually storing data.
     $entity = $this->reloadEntity($entity);
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php
index abf8905fdf9..9c49dbdfcf4 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php
@@ -55,7 +55,7 @@ class EntityUUIDTest extends EntityKernelTestBase {
       ->getStorage($entity_type)
       ->create(['name' => $this->randomMachineName()]);
     $uuid = $entity->uuid();
-    $this->assertTrue($uuid);
+    $this->assertNotEmpty($uuid);
 
     // Verify that the new UUID is different.
     $this->assertNotEqual($custom_entity->uuid(), $uuid);
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityViewBuilderTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityViewBuilderTest.php
index 4172772be78..90cc0ea0183 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityViewBuilderTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityViewBuilderTest.php
@@ -65,7 +65,7 @@ class EntityViewBuilderTest extends EntityKernelTestBase {
 
     // Test that a cache entry is created.
     $renderer->renderRoot($build);
-    $this->assertTrue($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
 
     // Re-save the entity and check that the cache entry has been deleted.
     $cache->set('kittens', 'Kitten data', Cache::PERMANENT, $build['#cache']['tags']);
@@ -77,7 +77,7 @@ class EntityViewBuilderTest extends EntityKernelTestBase {
     // delete the entity to check the cache entry is deleted.
     unset($build['#printed']);
     $renderer->renderRoot($build);
-    $this->assertTrue($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
     $entity_test->delete();
     $this->assertFalse($this->container->get('cache.' . $bin)->get($cid), 'The entity render cache has been cleared when the entity was deleted.');
 
@@ -121,7 +121,7 @@ class EntityViewBuilderTest extends EntityKernelTestBase {
     $renderer->renderRoot($build);
 
     // Test that a cache entry was created for the referenced entity.
-    $this->assertTrue($this->container->get('cache.' . $bin_reference)->get($cid_reference), 'The entity render element for the referenced entity has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.' . $bin_reference)->get($cid_reference), 'The entity render element for the referenced entity has been cached.');
 
     // Create another entity that references the first one.
     $entity_test = $this->createTestEntity('entity_test');
@@ -140,7 +140,7 @@ class EntityViewBuilderTest extends EntityKernelTestBase {
     $renderer->renderRoot($build);
 
     // Test that a cache entry is created.
-    $this->assertTrue($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.' . $bin)->get($cid), 'The entity render element has been cached.');
 
     // Save the entity and verify that both cache entries have been deleted.
     $entity_test_reference->save();
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/ValidReferenceConstraintValidatorTest.php b/core/tests/Drupal/KernelTests/Core/Entity/ValidReferenceConstraintValidatorTest.php
index 3ac600285e3..97b8215330d 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/ValidReferenceConstraintValidatorTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/ValidReferenceConstraintValidatorTest.php
@@ -61,18 +61,18 @@ class ValidReferenceConstraintValidatorTest extends EntityKernelTestBase {
 
     $typed_data = $this->typedData->create($definition, ['target_id' => $entity->id()]);
     $violations = $typed_data->validate();
-    $this->assertFalse($violations->count(), 'Validation passed for correct value.');
+    $this->assertEquals(0, $violations->count(), 'Validation passed for correct value.');
 
     // NULL is also considered a valid reference.
     $typed_data = $this->typedData->create($definition, ['target_id' => NULL]);
     $violations = $typed_data->validate();
-    $this->assertFalse($violations->count(), 'Validation passed for correct value.');
+    $this->assertEquals(0, $violations->count(), 'Validation passed for correct value.');
 
     $typed_data = $this->typedData->create($definition, ['target_id' => $entity->id()]);
     // Delete the referenced entity.
     $entity->delete();
     $violations = $typed_data->validate();
-    $this->assertTrue($violations->count(), 'Validation failed for incorrect value.');
+    $this->assertGreaterThan(0, $violations->count(), 'Validation failed for incorrect value.');
 
     // Make sure the information provided by a violation is correct.
     $violation = $violations[0];
diff --git a/core/tests/Drupal/KernelTests/Core/File/FileCopyTest.php b/core/tests/Drupal/KernelTests/Core/File/FileCopyTest.php
index d124cfd4956..532ecb63899 100644
--- a/core/tests/Drupal/KernelTests/Core/File/FileCopyTest.php
+++ b/core/tests/Drupal/KernelTests/Core/File/FileCopyTest.php
@@ -25,7 +25,7 @@ class FileCopyTest extends FileTestBase {
     // Copying to a new name.
     $desired_filepath = 'public://' . $this->randomMachineName();
     $new_filepath = \Drupal::service('file_system')->copy($uri, $desired_filepath, FileSystemInterface::EXISTS_ERROR);
-    $this->assertTrue($new_filepath, 'Copy was successful.');
+    $this->assertNotFalse($new_filepath, 'Copy was successful.');
     $this->assertEqual($new_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($uri), 'Original file remains.');
     $this->assertTrue(file_exists($new_filepath), 'New file exists.');
@@ -33,9 +33,9 @@ class FileCopyTest extends FileTestBase {
 
     // Copying with rename.
     $desired_filepath = 'public://' . $this->randomMachineName();
-    $this->assertTrue(file_put_contents($desired_filepath, ' '), 'Created a file so a rename will have to happen.');
+    $this->assertNotFalse(file_put_contents($desired_filepath, ' '), 'Created a file so a rename will have to happen.');
     $newer_filepath = \Drupal::service('file_system')->copy($uri, $desired_filepath, FileSystemInterface::EXISTS_RENAME);
-    $this->assertTrue($newer_filepath, 'Copy was successful.');
+    $this->assertNotFalse($newer_filepath, 'Copy was successful.');
     $this->assertNotEqual($newer_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($uri), 'Original file remains.');
     $this->assertTrue(file_exists($newer_filepath), 'New file exists.');
@@ -68,7 +68,7 @@ class FileCopyTest extends FileTestBase {
     /** @var \Drupal\Core\File\FileSystemInterface $file_system */
     $file_system = \Drupal::service('file_system');
     $new_filepath = $file_system->copy($uri, $uri, FileSystemInterface::EXISTS_RENAME);
-    $this->assertTrue($new_filepath, 'Copying onto itself with renaming works.');
+    $this->assertNotFalse($new_filepath, 'Copying onto itself with renaming works.');
     $this->assertNotEqual($new_filepath, $uri, 'Copied file has a new name.');
     $this->assertTrue(file_exists($uri), 'Original file exists after copying onto itself.');
     $this->assertTrue(file_exists($new_filepath), 'Copied file exists after copying onto itself.');
@@ -87,7 +87,7 @@ class FileCopyTest extends FileTestBase {
 
     // Copy the file into same directory with renaming works.
     $new_filepath = $file_system->copy($uri, $file_system->dirname($uri), FileSystemInterface::EXISTS_RENAME);
-    $this->assertTrue($new_filepath, 'Copying into same directory works.');
+    $this->assertNotFalse($new_filepath, 'Copying into same directory works.');
     $this->assertNotEqual($new_filepath, $uri, 'Copied file has a new name.');
     $this->assertTrue(file_exists($uri), 'Original file exists after copying onto itself.');
     $this->assertTrue(file_exists($new_filepath), 'Copied file exists after copying onto itself.');
diff --git a/core/tests/Drupal/KernelTests/Core/File/FileMoveTest.php b/core/tests/Drupal/KernelTests/Core/File/FileMoveTest.php
index 226903c55ec..fcee3b09fd3 100644
--- a/core/tests/Drupal/KernelTests/Core/File/FileMoveTest.php
+++ b/core/tests/Drupal/KernelTests/Core/File/FileMoveTest.php
@@ -27,7 +27,7 @@ class FileMoveTest extends FileTestBase {
     /** @var \Drupal\Core\File\FileSystemInterface $file_system */
     $file_system = \Drupal::service('file_system');
     $new_filepath = $file_system->move($uri, $desired_filepath, FileSystemInterface::EXISTS_ERROR);
-    $this->assertTrue($new_filepath, 'Move was successful.');
+    $this->assertNotFalse($new_filepath, 'Move was successful.');
     $this->assertEqual($new_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($new_filepath), 'File exists at the new location.');
     $this->assertFalse(file_exists($uri), 'No file remains at the old location.');
@@ -36,9 +36,9 @@ class FileMoveTest extends FileTestBase {
     // Moving with rename.
     $desired_filepath = 'public://' . $this->randomMachineName();
     $this->assertTrue(file_exists($new_filepath), 'File exists before moving.');
-    $this->assertTrue(file_put_contents($desired_filepath, ' '), 'Created a file so a rename will have to happen.');
+    $this->assertNotFalse(file_put_contents($desired_filepath, ' '), 'Created a file so a rename will have to happen.');
     $newer_filepath = $file_system->move($new_filepath, $desired_filepath, FileSystemInterface::EXISTS_RENAME);
-    $this->assertTrue($newer_filepath, 'Move was successful.');
+    $this->assertNotFalse($newer_filepath, 'Move was successful.');
     $this->assertNotEqual($newer_filepath, $desired_filepath, 'Returned expected filepath.');
     $this->assertTrue(file_exists($newer_filepath), 'File exists at the new location.');
     $this->assertFalse(file_exists($new_filepath), 'No file remains at the old location.');
@@ -74,7 +74,7 @@ class FileMoveTest extends FileTestBase {
 
     // Move the file onto itself with renaming will result in a new filename.
     $new_filepath = $file_system->move($uri, $uri, FileSystemInterface::EXISTS_RENAME);
-    $this->assertTrue($new_filepath, 'Moving onto itself with renaming works.');
+    $this->assertNotFalse($new_filepath, 'Moving onto itself with renaming works.');
     $this->assertFalse(file_exists($uri), 'Original file has been removed.');
     $this->assertTrue(file_exists($new_filepath), 'File exists after moving onto itself.');
   }
diff --git a/core/tests/Drupal/KernelTests/Core/File/FileSaveDataTest.php b/core/tests/Drupal/KernelTests/Core/File/FileSaveDataTest.php
index 74c2fa6f8a5..5424834ac47 100644
--- a/core/tests/Drupal/KernelTests/Core/File/FileSaveDataTest.php
+++ b/core/tests/Drupal/KernelTests/Core/File/FileSaveDataTest.php
@@ -24,7 +24,7 @@ class FileSaveDataTest extends FileTestBase {
 
     // Provide a filename.
     $filepath = $file_system->saveData($contents, 'public://asdf.txt', FileSystemInterface::EXISTS_REPLACE);
-    $this->assertTrue($filepath, 'Unnamed file saved correctly.');
+    $this->assertNotFalse($filepath, 'Unnamed file saved correctly.');
     $this->assertEqual('asdf.txt', \Drupal::service('file_system')->basename($filepath), 'File was named correctly.');
     $this->assertEqual($contents, file_get_contents($filepath), 'Contents of the file are correct.');
     $this->assertFilePermissions($filepath, 0777);
diff --git a/core/tests/Drupal/KernelTests/Core/File/ReadOnlyStreamWrapperTest.php b/core/tests/Drupal/KernelTests/Core/File/ReadOnlyStreamWrapperTest.php
index d313cd6a4f5..a57c0c7dac2 100644
--- a/core/tests/Drupal/KernelTests/Core/File/ReadOnlyStreamWrapperTest.php
+++ b/core/tests/Drupal/KernelTests/Core/File/ReadOnlyStreamWrapperTest.php
@@ -52,15 +52,15 @@ class ReadOnlyStreamWrapperTest extends FileTestBase {
     $this->assertFalse($handle, 'Unable to open a file for reading and writing with the read-only stream wrapper.');
     // Attempt to open a file in binary read mode
     $handle = fopen($uri, 'rb');
-    $this->assertTrue($handle, 'Able to open a file for reading in binary mode with the read-only stream wrapper.');
+    $this->assertNotFalse($handle, 'Able to open a file for reading in binary mode with the read-only stream wrapper.');
     $this->assertTrue(fclose($handle), 'Able to close file opened in binary mode using the read_only stream wrapper.');
     // Attempt to open a file in text read mode
     $handle = fopen($uri, 'rt');
-    $this->assertTrue($handle, 'Able to open a file for reading in text mode with the read-only stream wrapper.');
+    $this->assertNotFalse($handle, 'Able to open a file for reading in text mode with the read-only stream wrapper.');
     $this->assertTrue(fclose($handle), 'Able to close file opened in text mode using the read_only stream wrapper.');
     // Attempt to open a file in read mode
     $handle = fopen($uri, 'r');
-    $this->assertTrue($handle, 'Able to open a file for reading with the read-only stream wrapper.');
+    $this->assertNotFalse($handle, 'Able to open a file for reading with the read-only stream wrapper.');
     // Attempt to change file permissions
     $this->assertFalse(@chmod($uri, 0777), 'Unable to change file permissions when using read-only stream wrapper.');
     // Attempt to acquire an exclusive lock for writing
@@ -72,7 +72,7 @@ class ReadOnlyStreamWrapperTest extends FileTestBase {
     // Attempt to truncate the file
     $this->assertFalse(@ftruncate($handle, 0), 'Unable to truncate using the read-only stream wrapper.');
     // Attempt to write to the file
-    $this->assertFalse(@fwrite($handle, $this->randomMachineName()), 'Unable to write to file using the read-only stream wrapper.');
+    $this->assertEquals(0, @fwrite($handle, $this->randomMachineName()), 'Unable to write to file using the read-only stream wrapper.');
     // Attempt to flush output to the file
     $this->assertFalse(@fflush($handle), 'Unable to flush output to file using the read-only stream wrapper.');
     // Attempt to close the stream.  (Suppress errors, as fclose triggers fflush.)
diff --git a/core/tests/Drupal/KernelTests/Core/File/StreamWrapperTest.php b/core/tests/Drupal/KernelTests/Core/File/StreamWrapperTest.php
index 2a0cd9bfd43..ee438e58161 100644
--- a/core/tests/Drupal/KernelTests/Core/File/StreamWrapperTest.php
+++ b/core/tests/Drupal/KernelTests/Core/File/StreamWrapperTest.php
@@ -85,8 +85,8 @@ class StreamWrapperTest extends FileTestBase {
     $this->assertEqual($stream_wrapper_manager::getTarget('public://foo/bar.txt'), 'foo/bar.txt', 'Got a valid stream target from public://foo/bar.txt.');
     $this->assertEqual($stream_wrapper_manager::getTarget('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=='), 'image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==', t('Got a valid stream target from a data URI.'));
     $this->assertFalse($stream_wrapper_manager::getTarget('foo/bar.txt'), 'foo/bar.txt is not a valid stream.');
-    $this->assertFalse($stream_wrapper_manager::getTarget('public://'), 'public:// has no target.');
-    $this->assertFalse($stream_wrapper_manager::getTarget('data:'), 'data: has no target.');
+    $this->assertSame($stream_wrapper_manager::getTarget('public://'), '');
+    $this->assertSame($stream_wrapper_manager::getTarget('data:'), '');
 
     // Test file_build_uri() and
     // Drupal\Core\StreamWrapper\LocalStream::getDirectoryPath().
@@ -102,9 +102,9 @@ class StreamWrapperTest extends FileTestBase {
     // TemporaryStream::getExternalUrl() uses Url::fromRoute(), which needs
     // route information to work.
     $this->container->get('router.builder')->rebuild();
-    $this->assertTrue(strpos(file_create_url('temporary://test.txt'), 'system/temporary?file=test.txt'), 'Temporary external URL correctly built.');
-    $this->assertTrue(strpos(file_create_url('public://test.txt'), Settings::get('file_public_path') . '/test.txt'), 'Public external URL correctly built.');
-    $this->assertTrue(strpos(file_create_url('private://test.txt'), 'system/files/test.txt'), 'Private external URL correctly built.');
+    $this->assertContains('system/temporary?file=test.txt', file_create_url('temporary://test.txt'), 'Temporary external URL correctly built.');
+    $this->assertContains(Settings::get('file_public_path') . '/test.txt', file_create_url('public://test.txt'), 'Public external URL correctly built.');
+    $this->assertContains('system/files/test.txt', file_create_url('private://test.txt'), 'Private external URL correctly built.');
   }
 
   /**
@@ -116,7 +116,7 @@ class StreamWrapperTest extends FileTestBase {
 
     // Open for rw and place pointer at beginning of file so select will return.
     $handle = fopen($filename, 'c+');
-    $this->assertTrue($handle, 'Able to open a file for appending, reading and writing.');
+    $this->assertNotFalse($handle, 'Able to open a file for appending, reading and writing.');
 
     // Attempt to change options on the file stream: should all fail.
     $this->assertFalse(@stream_set_blocking($handle, 0), 'Unable to set to non blocking using a local stream wrapper.');
diff --git a/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php b/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php
index f6fb4f8713a..cbd0b8fe55a 100644
--- a/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php
@@ -60,7 +60,7 @@ class FormCacheTest extends KernelTestBase {
     $cached_form_state = new FormState();
     $cached_form = \Drupal::formBuilder()->getCache($this->formBuildId, $cached_form_state);
     $this->assertEqual($this->form['#property'], $cached_form['#property']);
-    $this->assertTrue(!empty($cached_form['#cache_token']), 'Form has a cache token');
+    $this->assertNotEmpty($cached_form['#cache_token'], 'Form has a cache token');
     $this->assertEqual($this->formState->get('example'), $cached_form_state->get('example'));
 
     // Test that the form cache isn't loaded when the session/token has changed.
@@ -69,16 +69,16 @@ class FormCacheTest extends KernelTestBase {
     \Drupal::state()->set('system.private_key', 'invalid');
     $cached_form_state = new FormState();
     $cached_form = \Drupal::formBuilder()->getCache($this->formBuildId, $cached_form_state);
-    $this->assertFalse($cached_form, 'No form returned from cache');
+    $this->assertNull($cached_form, 'No form returned from cache');
     $cached_form_state_example = $cached_form_state->get('example');
-    $this->assertTrue(empty($cached_form_state_example));
+    $this->assertEmpty($cached_form_state_example);
 
     // Test that loading the cache with a different form_id fails.
     $wrong_form_build_id = $this->randomMachineName(9);
     $cached_form_state = new FormState();
-    $this->assertFalse(\Drupal::formBuilder()->getCache($wrong_form_build_id, $cached_form_state), 'No form returned from cache');
+    $this->assertNull(\Drupal::formBuilder()->getCache($wrong_form_build_id, $cached_form_state), 'No form returned from cache');
     $cached_form_state_example = $cached_form_state->get('example');
-    $this->assertTrue(empty($cached_form_state_example), 'Cached form state was not loaded');
+    $this->assertEmpty($cached_form_state_example, 'Cached form state was not loaded');
   }
 
   /**
@@ -111,7 +111,7 @@ class FormCacheTest extends KernelTestBase {
     \Drupal::formBuilder()->setCache($this->formBuildId, $this->form, $this->formState);
 
     $cached_form_state = new FormState();
-    $this->assertFalse(\Drupal::formBuilder()->getCache($this->formBuildId, $cached_form_state), 'Expired form not returned from cache');
+    $this->assertNull(\Drupal::formBuilder()->getCache($this->formBuildId, $cached_form_state), 'Expired form not returned from cache');
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/Core/KeyValueStore/DatabaseStorageExpirableTest.php b/core/tests/Drupal/KernelTests/Core/KeyValueStore/DatabaseStorageExpirableTest.php
index 85c0f5acd45..30f21d335f6 100644
--- a/core/tests/Drupal/KernelTests/Core/KeyValueStore/DatabaseStorageExpirableTest.php
+++ b/core/tests/Drupal/KernelTests/Core/KeyValueStore/DatabaseStorageExpirableTest.php
@@ -46,13 +46,13 @@ class DatabaseStorageExpirableTest extends StorageTestBase {
     $stores[0]->setWithExpire('foo', $this->objects[0], rand(500, 100000));
     $this->assertIdenticalObject($this->objects[0], $stores[0]->get('foo'));
     // Verify that the other collection is not affected.
-    $this->assertFalse($stores[1]->get('foo'));
+    $this->assertNull($stores[1]->get('foo'));
 
     // Verify that an item can be updated with setWithExpire().
     $stores[0]->setWithExpire('foo', $this->objects[1], rand(500, 100000));
     $this->assertIdenticalObject($this->objects[1], $stores[0]->get('foo'));
     // Verify that the other collection is still not affected.
-    $this->assertFalse($stores[1]->get('foo'));
+    $this->assertNull($stores[1]->get('foo'));
 
     // Verify that the expirable data key is unique.
     $stores[1]->setWithExpire('foo', $this->objects[2], rand(500, 100000));
@@ -72,7 +72,7 @@ class DatabaseStorageExpirableTest extends StorageTestBase {
 
     // Verify that the other collection was not affected.
     $this->assertIdenticalObject($stores[1]->get('foo'), $this->objects[2]);
-    $this->assertFalse($stores[1]->get('bar'));
+    $this->assertNull($stores[1]->get('bar'));
 
     // Verify that all items in a collection can be retrieved.
     // Ensure that an item with the same name exists in the other collection.
@@ -89,9 +89,9 @@ class DatabaseStorageExpirableTest extends StorageTestBase {
 
     // Verify that multiple items can be deleted.
     $stores[0]->deleteMultiple(array_keys($values));
-    $this->assertFalse($stores[0]->get('foo'));
-    $this->assertFalse($stores[0]->get('bar'));
-    $this->assertFalse($stores[0]->getMultiple(['foo', 'bar']));
+    $this->assertNull($stores[0]->get('foo'));
+    $this->assertNull($stores[0]->get('bar'));
+    $this->assertEmpty($stores[0]->getMultiple(['foo', 'bar']));
     // Verify that the item in the other collection still exists.
     $this->assertIdenticalObject($this->objects[5], $stores[1]->get('foo'));
 
@@ -103,7 +103,7 @@ class DatabaseStorageExpirableTest extends StorageTestBase {
       $this->assertEqual(!$i, $stores[0]->setWithExpireIfNotExists($key, $this->objects[$i], rand(500, 100000)));
       $this->assertIdenticalObject($this->objects[0], $stores[0]->get($key));
       // Verify that the other collection is not affected.
-      $this->assertFalse($stores[1]->get($key));
+      $this->assertNull($stores[1]->get($key));
     }
 
     // Remove the item and try to set it again.
@@ -112,7 +112,7 @@ class DatabaseStorageExpirableTest extends StorageTestBase {
     // This time it should succeed.
     $this->assertIdenticalObject($this->objects[1], $stores[0]->get($key));
     // Verify that the other collection is still not affected.
-    $this->assertFalse($stores[1]->get($key));
+    $this->assertNull($stores[1]->get($key));
 
   }
 
@@ -129,7 +129,7 @@ class DatabaseStorageExpirableTest extends StorageTestBase {
 
     // Only the non-expired item should be returned.
     $this->assertFalse($stores[0]->has('yesterday'));
-    $this->assertFalse($stores[0]->get('yesterday'));
+    $this->assertNull($stores[0]->get('yesterday'));
     $this->assertTrue($stores[0]->has('troubles'));
     $this->assertIdentical($stores[0]->get('troubles'), 'here to stay');
     $this->assertIdentical(count($stores[0]->getMultiple(['yesterday', 'troubles'])), 1);
diff --git a/core/tests/Drupal/KernelTests/Core/KeyValueStore/KeyValueContentEntityStorageTest.php b/core/tests/Drupal/KernelTests/Core/KeyValueStore/KeyValueContentEntityStorageTest.php
index b9feca82faf..3c38e73667e 100644
--- a/core/tests/Drupal/KernelTests/Core/KeyValueStore/KeyValueContentEntityStorageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/KeyValueStore/KeyValueContentEntityStorageTest.php
@@ -44,14 +44,14 @@ class KeyValueContentEntityStorageTest extends KernelTestBase {
     $empty = EntityTestLabel::create();
     $this->assertIdentical($empty->id->value, NULL);
     $this->assertIdentical($empty->name->value, NULL);
-    $this->assertTrue($empty->uuid->value);
+    $this->assertNotEmpty($empty->uuid->value);
     $this->assertIdentical($empty->langcode->value, $default_langcode);
 
     // Verify ConfigEntity properties/methods on the newly created empty entity.
     $this->assertIdentical($empty->isNew(), TRUE);
     $this->assertIdentical($empty->bundle(), 'entity_test_label');
     $this->assertIdentical($empty->id(), NULL);
-    $this->assertTrue($empty->uuid());
+    $this->assertNotEmpty($empty->uuid());
     $this->assertIdentical($empty->label(), NULL);
 
     // Verify Entity properties/methods on the newly created empty entity.
@@ -93,7 +93,7 @@ class KeyValueContentEntityStorageTest extends KernelTestBase {
       'name' => $this->randomString(),
     ]);
     $this->assertIdentical($entity_test->id->value, $expected['id']);
-    $this->assertTrue($entity_test->uuid->value);
+    $this->assertNotEmpty($entity_test->uuid->value);
     $this->assertNotEqual($entity_test->uuid->value, $empty->uuid->value);
     $this->assertIdentical($entity_test->name->value, $expected['name']);
     $this->assertIdentical($entity_test->langcode->value, $default_langcode);
@@ -101,7 +101,7 @@ class KeyValueContentEntityStorageTest extends KernelTestBase {
     // Verify methods on the newly created entity.
     $this->assertIdentical($entity_test->isNew(), TRUE);
     $this->assertIdentical($entity_test->id(), $expected['id']);
-    $this->assertTrue($entity_test->uuid());
+    $this->assertNotEmpty($entity_test->uuid());
     $expected['uuid'] = $entity_test->uuid();
     $this->assertIdentical($entity_test->label(), $expected['name']);
 
diff --git a/core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php b/core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php
index 48af84d54a3..c7ba82478e7 100644
--- a/core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/KeyValueStore/StorageTestBase.php
@@ -57,13 +57,13 @@ abstract class StorageTestBase extends KernelTestBase {
     $this->assertIdenticalObject($this->objects[0], $stores[0]->get('foo'));
     // Verify that the other collection is not affected.
     $this->assertFalse($stores[1]->has('foo'));
-    $this->assertFalse($stores[1]->get('foo'));
+    $this->assertNull($stores[1]->get('foo'));
 
     // Verify that an item can be updated.
     $stores[0]->set('foo', $this->objects[1]);
     $this->assertIdenticalObject($this->objects[1], $stores[0]->get('foo'));
     // Verify that the other collection is still not affected.
-    $this->assertFalse($stores[1]->get('foo'));
+    $this->assertNull($stores[1]->get('foo'));
 
     // Verify that a collection/name pair is unique.
     $stores[1]->set('foo', $this->objects[2]);
@@ -73,13 +73,13 @@ abstract class StorageTestBase extends KernelTestBase {
     // Verify that an item can be deleted.
     $stores[0]->delete('foo');
     $this->assertFalse($stores[0]->has('foo'));
-    $this->assertFalse($stores[0]->get('foo'));
+    $this->assertNull($stores[0]->get('foo'));
 
     // Verify that the other collection is not affected.
     $this->assertTrue($stores[1]->has('foo'));
     $this->assertIdenticalObject($this->objects[2], $stores[1]->get('foo'));
     $stores[1]->delete('foo');
-    $this->assertFalse($stores[1]->get('foo'));
+    $this->assertNull($stores[1]->get('foo'));
 
     // Verify that multiple items can be stored.
     $values = [
@@ -95,8 +95,8 @@ abstract class StorageTestBase extends KernelTestBase {
     }
 
     // Verify that the other collection was not affected.
-    $this->assertFalse($stores[1]->get('foo'));
-    $this->assertFalse($stores[1]->get('bar'));
+    $this->assertNull($stores[1]->get('foo'));
+    $this->assertNull($stores[1]->get('bar'));
 
     // Verify that all items in a collection can be retrieved.
     // Ensure that an item with the same name exists in the other collection.
@@ -113,9 +113,9 @@ abstract class StorageTestBase extends KernelTestBase {
 
     // Verify that multiple items can be deleted.
     $stores[0]->deleteMultiple(array_keys($values));
-    $this->assertFalse($stores[0]->get('foo'));
-    $this->assertFalse($stores[0]->get('bar'));
-    $this->assertFalse($stores[0]->getMultiple(['foo', 'bar']));
+    $this->assertNull($stores[0]->get('foo'));
+    $this->assertNull($stores[0]->get('bar'));
+    $this->assertEmpty($stores[0]->getMultiple(['foo', 'bar']));
     // Verify that deleting no items does not cause an error.
     $stores[0]->deleteMultiple([]);
     // Verify that the item in the other collection still exists.
@@ -165,7 +165,7 @@ abstract class StorageTestBase extends KernelTestBase {
       $this->assertEqual(!$i, $stores[0]->setIfNotExists($key, $this->objects[$i]));
       $this->assertIdenticalObject($this->objects[0], $stores[0]->get($key));
       // Verify that the other collection is not affected.
-      $this->assertFalse($stores[1]->get($key));
+      $this->assertNull($stores[1]->get($key));
     }
 
     // Remove the item and try to set it again.
@@ -174,7 +174,7 @@ abstract class StorageTestBase extends KernelTestBase {
     // This time it should succeed.
     $this->assertIdenticalObject($this->objects[1], $stores[0]->get($key));
     // Verify that the other collection is still not affected.
-    $this->assertFalse($stores[1]->get($key));
+    $this->assertNull($stores[1]->get($key));
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Menu/MenuTreeStorageTest.php b/core/tests/Drupal/KernelTests/Core/Menu/MenuTreeStorageTest.php
index ad3f04d0ab4..a3d701f5c0c 100644
--- a/core/tests/Drupal/KernelTests/Core/Menu/MenuTreeStorageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Menu/MenuTreeStorageTest.php
@@ -353,7 +353,7 @@ class MenuTreeStorageTest extends KernelTestBase {
         $this->fail($message);
       }
       catch (\InvalidArgumentException $e) {
-        $this->assertTrue(preg_match('/^An invalid property name, .+ was specified. Allowed property names are:/', $e->getMessage()), 'Found expected exception message.');
+        $this->assertRegExp('/^An invalid property name, .+ was specified. Allowed property names are:/', $e->getMessage(), 'Found expected exception message.');
         $this->pass($message);
       }
     }
diff --git a/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php b/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
index 906e74bb6a1..dba7909b065 100644
--- a/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
@@ -190,7 +190,7 @@ class RenderElementTypesTest extends KernelTestBase {
     foreach ($elements as $element) {
       $xml = new \SimpleXMLElement(\Drupal::service('renderer')->renderRoot($element['value']));
       $result = $xml->xpath($element['expected']);
-      $this->assertTrue($result, '"' . $element['name'] . '" input rendered correctly by drupal_render().');
+      $this->assertNotEmpty($result, '"' . $element['name'] . '" input rendered correctly by drupal_render().');
     }
   }
 
@@ -221,7 +221,7 @@ class RenderElementTypesTest extends KernelTestBase {
     foreach ($elements as $element) {
       $xml = new \SimpleXMLElement(\Drupal::service('renderer')->renderRoot($element['value']));
       $result = $xml->xpath($element['expected']);
-      $this->assertTrue($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
+      $this->assertNotEmpty($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
     }
 
     // Set admin compact mode on for additional tests.
@@ -237,7 +237,7 @@ class RenderElementTypesTest extends KernelTestBase {
 
     $xml = new \SimpleXMLElement(\Drupal::service('renderer')->renderRoot($element['value']));
     $result = $xml->xpath($element['expected']);
-    $this->assertTrue($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
+    $this->assertNotEmpty($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Routing/RouteProviderTest.php b/core/tests/Drupal/KernelTests/Core/Routing/RouteProviderTest.php
index 57a8aa06dc2..7ab002d9c06 100644
--- a/core/tests/Drupal/KernelTests/Core/Routing/RouteProviderTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Routing/RouteProviderTest.php
@@ -523,10 +523,10 @@ class RouteProviderTest extends KernelTestBase {
     $request = Request::create($path, 'GET');
 
     $routes = $provider->getRoutesByPattern($path);
-    $this->assertFalse(count($routes), 'No path found with this pattern.');
+    $this->assertEmpty($routes, 'No path found with this pattern.');
 
     $collection = $provider->getRouteCollectionForRequest($request);
-    $this->assertTrue(count($collection) == 0, 'Empty route collection found with this pattern.');
+    $this->assertEmpty($collection, 'Empty route collection found with this pattern.');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php b/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php
index 929bfbec7d8..c9e3cfe6479 100644
--- a/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php
+++ b/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php
@@ -134,8 +134,8 @@ class TempStoreDatabaseTest extends KernelTestBase {
       ->condition('collection', "tempstore.shared.$collection")
       ->condition('name', $key)
       ->execute();
-    $this->assertFalse($stores[0]->get($key));
-    $this->assertFalse($stores[1]->get($key));
+    $this->assertNull($stores[0]->get($key));
+    $this->assertNull($stores[1]->get($key));
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/RegistryTest.php b/core/tests/Drupal/KernelTests/Core/Theme/RegistryTest.php
index d0649ba1107..41f028336bf 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/RegistryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/RegistryTest.php
@@ -40,10 +40,10 @@ class RegistryTest extends KernelTestBase {
     $lock_backend = \Drupal::lock();
     $registry = new ThemeRegistry($cid, $cache, $lock_backend, ['theme_registry'], $this->container->get('module_handler')->isLoaded());
 
-    $this->assertTrue(\Drupal::cache()->get($cid), 'Cache entry was created.');
+    $this->assertNotEmpty(\Drupal::cache()->get($cid), 'Cache entry was created.');
 
     // Trigger a cache miss for an offset.
-    $this->assertTrue($registry->get('theme_test_template_test'), 'Offset was returned correctly from the theme registry.');
+    $this->assertNotEmpty($registry->get('theme_test_template_test'), 'Offset was returned correctly from the theme registry.');
     // This will cause the ThemeRegistry class to write an updated version of
     // the cache entry when it is destroyed, usually at the end of the request.
     // Before that happens, manually delete the cache entry we created earlier
@@ -53,14 +53,14 @@ class RegistryTest extends KernelTestBase {
     // Destroy the class so that it triggers a cache write for the offset.
     $registry->destruct();
 
-    $this->assertTrue(\Drupal::cache()->get($cid), 'Cache entry was created.');
+    $this->assertNotEmpty(\Drupal::cache()->get($cid), 'Cache entry was created.');
 
     // Create a new instance of the class. Confirm that both the offset
     // requested previously, and one that has not yet been requested are both
     // available.
     $registry = new ThemeRegistry($cid, $cache, $lock_backend, ['theme_registry'], $this->container->get('module_handler')->isLoaded());
-    $this->assertTrue($registry->get('theme_test_template_test'), 'Offset was returned correctly from the theme registry');
-    $this->assertTrue($registry->get('theme_test_template_test_2'), 'Offset was returned correctly from the theme registry');
+    $this->assertNotEmpty($registry->get('theme_test_template_test'), 'Offset was returned correctly from the theme registry');
+    $this->assertNotEmpty($registry->get('theme_test_template_test_2'), 'Offset was returned correctly from the theme registry');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php b/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
index d625c2d9f68..c8dd0337a80 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
@@ -41,13 +41,13 @@ class ThemeInstallerTest extends KernelTestBase {
    * Verifies that no themes are installed by default.
    */
   public function testEmpty() {
-    $this->assertFalse($this->extensionConfig()->get('theme'));
+    $this->assertEmpty($this->extensionConfig()->get('theme'));
 
-    $this->assertFalse(array_keys($this->themeHandler()->listInfo()));
-    $this->assertFalse(array_keys(\Drupal::service('theme_handler')->listInfo()));
+    $this->assertEmpty(array_keys($this->themeHandler()->listInfo()));
+    $this->assertEmpty(array_keys(\Drupal::service('theme_handler')->listInfo()));
 
     // Rebuilding available themes should always yield results though.
-    $this->assertTrue($this->themeHandler()->rebuildThemeData()['stark'], 'ThemeHandler::rebuildThemeData() yields all available themes.');
+    $this->assertNotEmpty($this->themeHandler()->rebuildThemeData()['stark'], 'ThemeHandler::rebuildThemeData() yields all available themes.');
 
     // theme_get_setting() should return global default theme settings.
     $this->assertIdentical(theme_get_setting('features.favicon'), TRUE);
@@ -84,7 +84,7 @@ class ThemeInstallerTest extends KernelTestBase {
     $base_name = 'test_basetheme';
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
 
     $this->themeInstaller()->install([$name]);
 
@@ -106,7 +106,7 @@ class ThemeInstallerTest extends KernelTestBase {
     $name = 'non_existing_theme';
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
 
     try {
       $message = 'ThemeInstaller::install() throws UnknownExtensionException upon installing a non-existing theme.';
@@ -118,7 +118,7 @@ class ThemeInstallerTest extends KernelTestBase {
     }
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
   }
 
   /**
@@ -243,7 +243,7 @@ class ThemeInstallerTest extends KernelTestBase {
     $name = 'non_existing_theme';
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
 
     try {
       $message = 'ThemeInstaller::uninstall() throws UnknownExtensionException upon uninstalling a non-existing theme.';
@@ -255,7 +255,7 @@ class ThemeInstallerTest extends KernelTestBase {
     }
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
   }
 
   /**
@@ -265,20 +265,20 @@ class ThemeInstallerTest extends KernelTestBase {
     $name = 'test_basetheme';
 
     $this->themeInstaller()->install([$name]);
-    $this->assertTrue($this->config("$name.settings")->get());
+    $this->assertNotEmpty($this->config("$name.settings")->get());
 
     $this->themeInstaller()->uninstall([$name]);
 
-    $this->assertFalse(array_keys($this->themeHandler()->listInfo()));
+    $this->assertEmpty(array_keys($this->themeHandler()->listInfo()));
 
-    $this->assertFalse($this->config("$name.settings")->get());
+    $this->assertEmpty($this->config("$name.settings")->get());
 
     // Ensure that the uninstalled theme can be installed again.
     $this->themeInstaller()->install([$name]);
     $themes = $this->themeHandler()->listInfo();
     $this->assertTrue(isset($themes[$name]));
     $this->assertEqual($themes[$name]->getName(), $name);
-    $this->assertTrue($this->config("$name.settings")->get());
+    $this->assertNotEmpty($this->config("$name.settings")->get());
   }
 
   /**
diff --git a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php
index 0785472243c..92b1b9ebd7b 100644
--- a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php
+++ b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit6/TestCompatibilityTrait.php
@@ -18,6 +18,7 @@ trait TestCompatibilityTrait {
       parent::assertTrue($actual, $message);
     }
     else {
+      @trigger_error('Support for asserting against non-boolean values in ::assertTrue is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Use a different assert method, for example, ::assertNotEmpty(). See https://www.drupal.org/node/3082086', E_USER_DEPRECATED);
       parent::assertNotEmpty($actual, $message);
     }
   }
@@ -33,6 +34,7 @@ trait TestCompatibilityTrait {
       parent::assertFalse($actual, $message);
     }
     else {
+      @trigger_error('Support for asserting against non-boolean values in ::assertFalse is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Use a different assert method, for example, ::assertEmpty(). See https://www.drupal.org/node/3082086', E_USER_DEPRECATED);
       parent::assertEmpty($actual, $message);
     }
   }
diff --git a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit7/TestCompatibilityTrait.php b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit7/TestCompatibilityTrait.php
index a80dfbbf790..3d10e151a93 100644
--- a/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit7/TestCompatibilityTrait.php
+++ b/core/tests/Drupal/TestTools/PhpUnitCompatibility/PhpUnit7/TestCompatibilityTrait.php
@@ -18,6 +18,7 @@ trait TestCompatibilityTrait {
       parent::assertTrue($actual, $message);
     }
     else {
+      @trigger_error('Support for asserting against non-boolean values in ::assertTrue is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Use a different assert method, for example, ::assertNotEmpty(). See https://www.drupal.org/node/3082086', E_USER_DEPRECATED);
       parent::assertNotEmpty($actual, $message);
     }
   }
@@ -33,6 +34,7 @@ trait TestCompatibilityTrait {
       parent::assertFalse($actual, $message);
     }
     else {
+      @trigger_error('Support for asserting against non-boolean values in ::assertFalse is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Use a different assert method, for example, ::assertEmpty(). See https://www.drupal.org/node/3082086', E_USER_DEPRECATED);
       parent::assertEmpty($actual, $message);
     }
   }
diff --git a/core/tests/Drupal/Tests/Core/Assert/KernelAssertLegacyTraitTest.php b/core/tests/Drupal/Tests/Core/Assert/KernelAssertLegacyTraitTest.php
new file mode 100644
index 00000000000..497bd342317
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Assert/KernelAssertLegacyTraitTest.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Drupal\Tests\Core\Assert;
+
+use Drupal\KernelTests\AssertLegacyTrait;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\KernelTests\AssertLegacyTrait
+ * @group Assert
+ * @group legacy
+ */
+class KernelAssertLegacyTraitTest extends UnitTestCase {
+
+  use AssertLegacyTrait;
+
+  /**
+   * @expectedDeprecation Support for asserting against non-boolean values in ::assertTrue is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Use a different assert method, for example, ::assertNotEmpty(). See https://www.drupal.org/node/3082086
+   */
+  public function testAssertTrue() {
+    $this->assertTrue(1);
+  }
+
+  /**
+   * @expectedDeprecation Support for asserting against non-boolean values in ::assertFalse is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Use a different assert method, for example, ::assertEmpty(). See https://www.drupal.org/node/3082086
+   */
+  public function testAssertFalse() {
+    $this->assertFalse(0);
+  }
+
+}