diff --git a/core/modules/action/tests/src/Functional/ConfigurationTest.php b/core/modules/action/tests/src/Functional/ConfigurationTest.php
index 051ba5032b7..8844cb0979b 100644
--- a/core/modules/action/tests/src/Functional/ConfigurationTest.php
+++ b/core/modules/action/tests/src/Functional/ConfigurationTest.php
@@ -6,8 +6,7 @@ use Drupal\system\Entity\Action;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests complex actions configuration by adding, editing, and deleting a
- * complex action.
+ * Tests complex actions configuration.
  *
  * @group action
  */
diff --git a/core/modules/block/tests/src/Functional/BlockHiddenRegionTest.php b/core/modules/block/tests/src/Functional/BlockHiddenRegionTest.php
index 06cbe8b2370..7f5906be7d7 100644
--- a/core/modules/block/tests/src/Functional/BlockHiddenRegionTest.php
+++ b/core/modules/block/tests/src/Functional/BlockHiddenRegionTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\block\Functional;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests that a newly installed theme does not inherit blocks to its hidden
- * regions.
+ * Tests that blocks are not added to hidden regions on theme installation.
  *
  * @group block
  */
diff --git a/core/modules/block/tests/src/Functional/BlockInvalidRegionTest.php b/core/modules/block/tests/src/Functional/BlockInvalidRegionTest.php
index f11dc77fd37..9a0052b07a2 100644
--- a/core/modules/block/tests/src/Functional/BlockInvalidRegionTest.php
+++ b/core/modules/block/tests/src/Functional/BlockInvalidRegionTest.php
@@ -6,8 +6,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\block\Entity\Block;
 
 /**
- * Tests that an active block assigned to a non-existing region triggers the
- * warning message and is disabled.
+ * Tests that blocks assigned to invalid regions are disabled with a warning.
  *
  * @group block
  */
diff --git a/core/modules/block/tests/src/Functional/BlockLanguageTest.php b/core/modules/block/tests/src/Functional/BlockLanguageTest.php
index 7020fd5df9c..95c2b3fa4df 100644
--- a/core/modules/block/tests/src/Functional/BlockLanguageTest.php
+++ b/core/modules/block/tests/src/Functional/BlockLanguageTest.php
@@ -6,8 +6,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\block\Entity\Block;
 
 /**
- * Tests if a block can be configured to be only visible on a particular
- * language.
+ * Tests per-language block configuration.
  *
  * @group block
  */
diff --git a/core/modules/comment/tests/src/Functional/CommentTitleTest.php b/core/modules/comment/tests/src/Functional/CommentTitleTest.php
index 69d65cf4851..5f94a88e9a2 100644
--- a/core/modules/comment/tests/src/Functional/CommentTitleTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentTitleTest.php
@@ -3,8 +3,7 @@
 namespace Drupal\Tests\comment\Functional;
 
 /**
- * Tests to ensure that appropriate and accessible markup is created for comment
- * titles.
+ * Tests that appropriate and accessible markup is created for comment titles.
  *
  * @group comment
  */
diff --git a/core/modules/comment/tests/src/Functional/CommentTokenReplaceTest.php b/core/modules/comment/tests/src/Functional/CommentTokenReplaceTest.php
index 4fffc6e042d..40a6484ebb7 100644
--- a/core/modules/comment/tests/src/Functional/CommentTokenReplaceTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentTokenReplaceTest.php
@@ -13,8 +13,7 @@ use Drupal\taxonomy\Entity\Vocabulary;
 use Drupal\user\Entity\User;
 
 /**
- * Generates text using placeholders for dummy content to check comment token
- * replacement.
+ * Tests comment token replacement.
  *
  * @group comment
  */
diff --git a/core/modules/comment/tests/src/Kernel/CommentDefaultFormatterCacheTagsTest.php b/core/modules/comment/tests/src/Kernel/CommentDefaultFormatterCacheTagsTest.php
index 4df8d4cd51f..a0dd05c23a8 100644
--- a/core/modules/comment/tests/src/Kernel/CommentDefaultFormatterCacheTagsTest.php
+++ b/core/modules/comment/tests/src/Kernel/CommentDefaultFormatterCacheTagsTest.php
@@ -12,8 +12,7 @@ use Drupal\comment\Entity\Comment;
 use Drupal\entity_test\Entity\EntityTest;
 
 /**
- * Tests the bubbling up of comment cache tags when using the Comment list
- * formatter on an entity.
+ * Tests comment cache tag bubbling up when using the Comment list formatter.
  *
  * @group comment
  */
diff --git a/core/modules/config/tests/src/Functional/ConfigInstallProfileOverrideTest.php b/core/modules/config/tests/src/Functional/ConfigInstallProfileOverrideTest.php
index e022d5f126d..4a5ca18c7a2 100644
--- a/core/modules/config/tests/src/Functional/ConfigInstallProfileOverrideTest.php
+++ b/core/modules/config/tests/src/Functional/ConfigInstallProfileOverrideTest.php
@@ -12,8 +12,10 @@ use Drupal\tour\Entity\Tour;
 use Drupal\user\Entity\Role;
 
 /**
- * Tests installation and removal of configuration objects in install, disable
- * and uninstall functionality.
+ * Tests that configuration objects are correct after various operations.
+ *
+ * The installation and removal of configuration objects in install, disable
+ * and uninstall functionality is tested.
  *
  * @group config
  */
diff --git a/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php b/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php
index fc27b7d9bd8..314c3d50dbb 100644
--- a/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php
+++ b/core/modules/config/tests/src/Functional/ConfigInstallWebTest.php
@@ -11,8 +11,10 @@ use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests installation and removal of configuration objects in install, disable
- * and uninstall functionality.
+ * Tests configuration objects before and after module install and uninstall.
+ *
+ * The installation and removal of configuration objects in install, disable
+ * and uninstall functionality is tested.
  *
  * @group config
  */
diff --git a/core/modules/contextual/tests/src/Functional/ContextualDynamicContextTest.php b/core/modules/contextual/tests/src/Functional/ContextualDynamicContextTest.php
index f1fb389b0d8..b04f716a56b 100644
--- a/core/modules/contextual/tests/src/Functional/ContextualDynamicContextTest.php
+++ b/core/modules/contextual/tests/src/Functional/ContextualDynamicContextTest.php
@@ -10,8 +10,7 @@ use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests if contextual links are showing on the front page depending on
- * permissions.
+ * Tests contextual link display on the front page based on permissions.
  *
  * @group contextual
  */
diff --git a/core/modules/dblog/tests/src/Functional/DbLogTest.php b/core/modules/dblog/tests/src/Functional/DbLogTest.php
index 173c17795ae..9f16b406fb5 100644
--- a/core/modules/dblog/tests/src/Functional/DbLogTest.php
+++ b/core/modules/dblog/tests/src/Functional/DbLogTest.php
@@ -14,8 +14,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\system\Functional\Menu\AssertBreadcrumbTrait;
 
 /**
- * Generate events and verify dblog entries; verify user access to log reports
- * based on permissions.
+ * Verifies log entries and user access based on permissions.
  *
  * @group dblog
  */
diff --git a/core/modules/dblog/tests/src/Functional/DbLogViewsTest.php b/core/modules/dblog/tests/src/Functional/DbLogViewsTest.php
index 284b3bab9b9..d6794a01c49 100644
--- a/core/modules/dblog/tests/src/Functional/DbLogViewsTest.php
+++ b/core/modules/dblog/tests/src/Functional/DbLogViewsTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\dblog\Functional;
 use Drupal\views\Views;
 
 /**
- * Generate events and verify dblog entries; verify user access to log reports
- * based on permissions. Using the dblog UI generated by a View.
+ * Verifies user access to log reports based on permissions.
  *
  * @see Drupal\dblog\Tests\DbLogTest
  *
diff --git a/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php b/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php
index b7dbac9c98c..0ab8be68cac 100644
--- a/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php
+++ b/core/modules/field/tests/src/Functional/FieldImportDeleteUninstallUiTest.php
@@ -7,8 +7,7 @@ use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 
 /**
- * Delete field storages and fields during config synchronization and uninstall
- * module that provides the field type through the UI.
+ * Tests deleting field storage when a module in uninstalled through the UI.
  *
  * @group field
  * @see \Drupal\field\ConfigImporterFieldPurger
diff --git a/core/modules/field/tests/src/Kernel/FieldDataCountTest.php b/core/modules/field/tests/src/Kernel/FieldDataCountTest.php
index 4b067276c3d..f521d6236ba 100644
--- a/core/modules/field/tests/src/Kernel/FieldDataCountTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldDataCountTest.php
@@ -10,8 +10,7 @@ use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 
 /**
- * Tests counting field data records and the hasData() method on
- * FieldStorageConfig entity.
+ * Tests the count of field data records.
  *
  * @group field
  * @see \Drupal\Core\Entity\FieldableEntityStorageInterface::countFieldData()
diff --git a/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php b/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php
index 48e553cd32c..9e2e27bac4c 100644
--- a/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldImportDeleteUninstallTest.php
@@ -7,8 +7,7 @@ use Drupal\field\Entity\FieldConfig;
 use Drupal\field\Entity\FieldStorageConfig;
 
 /**
- * Delete field storages and fields during config synchronization and uninstall
- * module that provides the field type.
+ * Tests field storages and fields deletion during config synchronization.
  *
  * @group field
  * @see \Drupal\field\ConfigImporterFieldPurger
diff --git a/core/modules/file/tests/src/Functional/FileFieldValidateTest.php b/core/modules/file/tests/src/Functional/FileFieldValidateTest.php
index 005bc1badbb..292d24abc07 100644
--- a/core/modules/file/tests/src/Functional/FileFieldValidateTest.php
+++ b/core/modules/file/tests/src/Functional/FileFieldValidateTest.php
@@ -8,8 +8,10 @@ use Drupal\field\Entity\FieldConfig;
 use Drupal\file\Entity\File;
 
 /**
- * Tests validation functions such as file type, max file size, max size per
- * node, and required.
+ * Tests file field validation functions.
+ *
+ * Values validated include the file type, max file size, max size per node,
+ * and whether the field is required.
  *
  * @group file
  */
diff --git a/core/modules/file/tests/src/Functional/FileManagedTestBase.php b/core/modules/file/tests/src/Functional/FileManagedTestBase.php
index 689dd3b7b1e..61a0f5b76ba 100644
--- a/core/modules/file/tests/src/Functional/FileManagedTestBase.php
+++ b/core/modules/file/tests/src/Functional/FileManagedTestBase.php
@@ -8,8 +8,7 @@ use Drupal\file\FileInterface;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Base class for file tests that use the file_test module to test uploads and
- * hooks.
+ * Provides a base class for testing files with the file_test module.
  */
 abstract class FileManagedTestBase extends BrowserTestBase {
 
diff --git a/core/modules/file/tests/src/Functional/FileTokenReplaceTest.php b/core/modules/file/tests/src/Functional/FileTokenReplaceTest.php
index 041b0fe20ed..86fe0ed5d17 100644
--- a/core/modules/file/tests/src/Functional/FileTokenReplaceTest.php
+++ b/core/modules/file/tests/src/Functional/FileTokenReplaceTest.php
@@ -8,8 +8,7 @@ use Drupal\Core\Render\BubbleableMetadata;
 use Drupal\file\Entity\File;
 
 /**
- * Generates text using placeholders for dummy content to check file token
- * replacement.
+ * Tests file token replacement.
  *
  * @group file
  */
diff --git a/core/modules/file/tests/src/FunctionalJavascript/FileFieldValidateTest.php b/core/modules/file/tests/src/FunctionalJavascript/FileFieldValidateTest.php
index 6c667ecd126..1d50b3bfd7a 100644
--- a/core/modules/file/tests/src/FunctionalJavascript/FileFieldValidateTest.php
+++ b/core/modules/file/tests/src/FunctionalJavascript/FileFieldValidateTest.php
@@ -7,8 +7,10 @@ use Drupal\Tests\file\Functional\FileFieldCreationTrait;
 use Drupal\Tests\TestFileCreationTrait;
 
 /**
- * Tests validation functions such as file type, max file size, max size per
- * node, and required.
+ * Tests file field validation functions.
+ *
+ * Values validated include the file type, max file size, max size per node,
+ * and whether the field is required.
  *
  * @group file
  */
diff --git a/core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php b/core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php
index 4441fd333f9..d2ad5dab969 100644
--- a/core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php
+++ b/core/modules/file/tests/src/Kernel/FileManagedUnitTestBase.php
@@ -9,8 +9,7 @@ use Drupal\KernelTests\KernelTestBase;
 use Drupal\user\Entity\User;
 
 /**
- * Base class for file unit tests that use the file_test module to test uploads and
- * hooks.
+ * Provides a base class for testing file uploads and hook invocations.
  */
 abstract class FileManagedUnitTestBase extends KernelTestBase {
 
diff --git a/core/modules/filter/tests/src/Functional/FilterSecurityTest.php b/core/modules/filter/tests/src/Functional/FilterSecurityTest.php
index 0e200f16c6f..ebe5a787747 100644
--- a/core/modules/filter/tests/src/Functional/FilterSecurityTest.php
+++ b/core/modules/filter/tests/src/Functional/FilterSecurityTest.php
@@ -8,9 +8,7 @@ use Drupal\filter\Plugin\FilterInterface;
 use Drupal\user\RoleInterface;
 
 /**
- * Tests the behavior of check_markup() when a filter or text format vanishes,
- * or when check_markup() is called in such a way that it is instructed to skip
- * all filters of the "FilterInterface::TYPE_HTML_RESTRICTOR" type.
+ * Tests HTML filtering with missing or skipped filters or text formats.
  *
  * @group filter
  */
diff --git a/core/modules/language/tests/src/Functional/LanguageListModuleInstallTest.php b/core/modules/language/tests/src/Functional/LanguageListModuleInstallTest.php
index 9a7e9ddabec..2b3fcf49e3a 100644
--- a/core/modules/language/tests/src/Functional/LanguageListModuleInstallTest.php
+++ b/core/modules/language/tests/src/Functional/LanguageListModuleInstallTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\language\Functional;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests enabling Language if a module exists that calls
- * LanguageManager::getLanguages() during installation.
+ * Tests that the language list is not empty when language is installed.
  *
  * @group language
  */
diff --git a/core/modules/language/tests/src/Kernel/Condition/LanguageConditionTest.php b/core/modules/language/tests/src/Kernel/Condition/LanguageConditionTest.php
index d664fd5b435..2175a3a9ee0 100644
--- a/core/modules/language/tests/src/Kernel/Condition/LanguageConditionTest.php
+++ b/core/modules/language/tests/src/Kernel/Condition/LanguageConditionTest.php
@@ -6,8 +6,7 @@ use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Tests that the language condition, provided by the language module, is
- * working properly.
+ * Tests the language condition plugin.
  *
  * @group language
  */
diff --git a/core/modules/language/tests/src/Kernel/LanguageDependencyInjectionTest.php b/core/modules/language/tests/src/Kernel/LanguageDependencyInjectionTest.php
index dff6af4c2b3..954614d3a5d 100644
--- a/core/modules/language/tests/src/Kernel/LanguageDependencyInjectionTest.php
+++ b/core/modules/language/tests/src/Kernel/LanguageDependencyInjectionTest.php
@@ -6,8 +6,7 @@ use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\language\Exception\DeleteDefaultLanguageException;
 
 /**
- * Compares the default language from $GLOBALS against the dependency injected
- * language object.
+ * Tests that a language object can be injected.
  *
  * @group language
  */
diff --git a/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateLanguageContentSettingsTest.php b/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateLanguageContentSettingsTest.php
index 394e18e591c..9a3d46335c3 100644
--- a/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateLanguageContentSettingsTest.php
+++ b/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateLanguageContentSettingsTest.php
@@ -6,7 +6,9 @@ use Drupal\language\Entity\ContentLanguageSettings;
 use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
 
 /**
- * Tests migration of language content setting variables,
+ * Tests the migration of language-related settings.
+ *
+ * Settings tested include language content setting variables,
  * language_content_type_$type, i18n_node_options_* and i18n_lock_node_*.
  *
  * @group migrate_drupal_6
diff --git a/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateLanguageContentSettingsTest.php b/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateLanguageContentSettingsTest.php
index b86378c2d57..ed65ee448ad 100644
--- a/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateLanguageContentSettingsTest.php
+++ b/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateLanguageContentSettingsTest.php
@@ -6,7 +6,9 @@ use Drupal\language\Entity\ContentLanguageSettings;
 use Drupal\Tests\migrate_drupal\Kernel\d7\MigrateDrupal7TestBase;
 
 /**
- * Tests migration of language content setting variables,
+ * Tests the migration of language-related settings.
+ *
+ * Settings tested include the language content setting variables,
  * language_content_type_$type, i18n_node_options_* and i18n_lock_node_*.
  *
  * @group migrate_drupal_7
diff --git a/core/modules/layout_builder/tests/modules/layout_builder_element_test/src/EventSubscriber/TestPrepareLayout.php b/core/modules/layout_builder/tests/modules/layout_builder_element_test/src/EventSubscriber/TestPrepareLayout.php
index 0d9c1afd502..7162b967153 100644
--- a/core/modules/layout_builder/tests/modules/layout_builder_element_test/src/EventSubscriber/TestPrepareLayout.php
+++ b/core/modules/layout_builder/tests/modules/layout_builder_element_test/src/EventSubscriber/TestPrepareLayout.php
@@ -12,8 +12,7 @@ use Drupal\layout_builder\SectionComponent;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 
 /**
- * An event subscriber to test altering section storage via the
- * \Drupal\layout_builder\Event\PrepareLayoutEvent.
+ * Provides an event subscriber for testing section storage alteration.
  *
  * @see \Drupal\layout_builder\Event\PrepareLayoutEvent
  * @see \Drupal\layout_builder\Element\LayoutBuilder::prepareLayout()
diff --git a/core/modules/locale/tests/src/Functional/LocaleContentTest.php b/core/modules/locale/tests/src/Functional/LocaleContentTest.php
index ce06b9d2a3f..2a06080046d 100644
--- a/core/modules/locale/tests/src/Functional/LocaleContentTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleContentTest.php
@@ -7,8 +7,7 @@ use Drupal\Core\Language\LanguageInterface;
 use Drupal\node\NodeInterface;
 
 /**
- * Tests you can enable multilingual support on content types and configure a
- * language for a node.
+ * Tests multilingual support for content types and individual nodes.
  *
  * @group locale
  */
diff --git a/core/modules/locale/tests/src/Functional/LocaleTranslationUiTest.php b/core/modules/locale/tests/src/Functional/LocaleTranslationUiTest.php
index cdedb12cd35..cbca227ad7f 100644
--- a/core/modules/locale/tests/src/Functional/LocaleTranslationUiTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleTranslationUiTest.php
@@ -9,8 +9,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Core\Language\LanguageInterface;
 
 /**
- * Adds a new locale and translates its name. Checks the validation of
- * translation strings and search results.
+ * Tests the validation of translation strings and search results.
  *
  * @group locale
  */
diff --git a/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php b/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php
index 27b49b27ee8..bc128897293 100644
--- a/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php
+++ b/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php
@@ -15,8 +15,9 @@ use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\Routing\Route;
 
 /**
- * Ensures that rendered menu links bubble the necessary bubbleable metadata
- * for outbound path/route processing.
+ * Ensures that rendered menu links bubble the necessary bubbleable metadata.
+ *
+ * This for outbound path/route processing.
  *
  * @group menu_link_content
  */
diff --git a/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php b/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php
index 96411404b56..f6000557d3c 100644
--- a/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php
+++ b/core/modules/menu_ui/tests/src/Functional/MenuUiTest.php
@@ -15,8 +15,10 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\menu_ui\Traits\MenuUiTrait;
 
 /**
- * Add a custom menu, add menu links to the custom menu and Tools menu, check
- * their data, and delete them using the UI.
+ * Tests the menu UI.
+ *
+ * This test adds a custom menu, adds menu links to the custom menu and the
+ * Tools menu, checks their data, and deletes them using the UI.
  *
  * @group menu_ui
  */
diff --git a/core/modules/migrate/tests/src/Unit/MigrateSourceTest.php b/core/modules/migrate/tests/src/Unit/MigrateSourceTest.php
index 8f5d2e627d1..2afddd72d4e 100644
--- a/core/modules/migrate/tests/src/Unit/MigrateSourceTest.php
+++ b/core/modules/migrate/tests/src/Unit/MigrateSourceTest.php
@@ -500,8 +500,10 @@ class StubSourcePlugin extends SourcePluginBase {
 }
 
 /**
- * Stubbed source plugin with a generator as iterator. Also it overwrites the
- * $skipCount, $cacheCounts and $trackChanges properties.
+ * Defines a stubbed source plugin with a generator as iterator.
+ *
+ * This stub overwrites the $skipCount, $cacheCounts, and $trackChanges
+ * properties.
  */
 class StubSourceGeneratorPlugin extends StubSourcePlugin {
 
diff --git a/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php b/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php
index 31fee1ccd26..50e5e62eb11 100644
--- a/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php
+++ b/core/modules/node/tests/src/Functional/NodeAccessRebuildNodeGrantsTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\node\Functional;
 use Drupal\node\Entity\NodeType;
 
 /**
- * Ensures that node access rebuild functions work correctly even
- * when other modules implements hook_node_grants().
+ * Tests node access rebuild functions with multiple node access modules.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Functional/NodePostSettingsTest.php b/core/modules/node/tests/src/Functional/NodePostSettingsTest.php
index 6610cc67e69..ba22129b36a 100644
--- a/core/modules/node/tests/src/Functional/NodePostSettingsTest.php
+++ b/core/modules/node/tests/src/Functional/NodePostSettingsTest.php
@@ -3,8 +3,7 @@
 namespace Drupal\Tests\node\Functional;
 
 /**
- * Tests that the post information (submitted by Username on date) text displays
- * appropriately.
+ * Tests the node setting for displaying author and date information.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Functional/NodeRevisionsAllTest.php b/core/modules/node/tests/src/Functional/NodeRevisionsAllTest.php
index a9687f63e7b..b496cf6beb6 100644
--- a/core/modules/node/tests/src/Functional/NodeRevisionsAllTest.php
+++ b/core/modules/node/tests/src/Functional/NodeRevisionsAllTest.php
@@ -6,8 +6,7 @@ use Drupal\Core\Database\Database;
 use Drupal\node\NodeInterface;
 
 /**
- * Create a node with revisions and test viewing, saving, reverting, and
- * deleting revisions for user with access to all.
+ * Tests global node CRUD operation permissions.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Functional/NodeRevisionsTest.php b/core/modules/node/tests/src/Functional/NodeRevisionsTest.php
index d6ce481ad1b..d9df596421a 100644
--- a/core/modules/node/tests/src/Functional/NodeRevisionsTest.php
+++ b/core/modules/node/tests/src/Functional/NodeRevisionsTest.php
@@ -11,8 +11,7 @@ use Drupal\node\Entity\Node;
 use Drupal\node\NodeInterface;
 
 /**
- * Create a node with revisions and test viewing, saving, reverting, and
- * deleting revisions for users with access for this content type.
+ * Tests per-content-type node CRUD operation permissions.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Functional/NodeTitleXSSTest.php b/core/modules/node/tests/src/Functional/NodeTitleXSSTest.php
index dcbac6a1ef0..87d36e2c490 100644
--- a/core/modules/node/tests/src/Functional/NodeTitleXSSTest.php
+++ b/core/modules/node/tests/src/Functional/NodeTitleXSSTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\node\Functional;
 use Drupal\Component\Utility\Html;
 
 /**
- * Create a node with dangerous tags in its title and test that they are
- * escaped.
+ * Tests that dangerous tags in the node title are escaped.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareCombinationTest.php b/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareCombinationTest.php
index f8a2e5f0e2b..a3202cfc5b8 100644
--- a/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareCombinationTest.php
+++ b/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareCombinationTest.php
@@ -11,8 +11,7 @@ use Drupal\user\Entity\User;
 use Drupal\field\Entity\FieldStorageConfig;
 
 /**
- * Tests node access functionality with multiple languages and two node access
- * modules.
+ * Tests node access with multiple languages and two node access modules.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareTest.php b/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareTest.php
index c3fc89d2f28..c4afd4d319a 100644
--- a/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareTest.php
+++ b/core/modules/node/tests/src/Kernel/NodeAccessLanguageAwareTest.php
@@ -10,8 +10,7 @@ use Drupal\user\Entity\User;
 use Drupal\field\Entity\FieldStorageConfig;
 
 /**
- * Tests node_access and select queries with node_access tag functionality with
- * multiple languages with node_access_test_language which is language-aware.
+ * Tests multilingual node access with a language-aware module.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Kernel/NodeAccessLanguageTest.php b/core/modules/node/tests/src/Kernel/NodeAccessLanguageTest.php
index 7e9f8873006..29a2e96a58e 100644
--- a/core/modules/node/tests/src/Kernel/NodeAccessLanguageTest.php
+++ b/core/modules/node/tests/src/Kernel/NodeAccessLanguageTest.php
@@ -9,8 +9,7 @@ use Drupal\node\Entity\NodeType;
 use Drupal\user\Entity\User;
 
 /**
- * Tests node_access and select queries with node_access tag functionality with
- * multiple languages with a test node access module that is not language-aware.
+ * Tests multilingual node access with a module that is not language-aware.
  *
  * @group node
  */
diff --git a/core/modules/node/tests/src/Kernel/NodeTokenReplaceTest.php b/core/modules/node/tests/src/Kernel/NodeTokenReplaceTest.php
index 4f10dce7244..a18faf871e8 100644
--- a/core/modules/node/tests/src/Kernel/NodeTokenReplaceTest.php
+++ b/core/modules/node/tests/src/Kernel/NodeTokenReplaceTest.php
@@ -9,8 +9,7 @@ use Drupal\node\Entity\NodeType;
 use Drupal\Tests\system\Kernel\Token\TokenReplaceKernelTestBase;
 
 /**
- * Generates text using placeholders for dummy content to check node token
- * replacement.
+ * Tests node token replacement.
  *
  * @group node
  */
diff --git a/core/modules/path/tests/src/Functional/PathAliasTest.php b/core/modules/path/tests/src/Functional/PathAliasTest.php
index b55a8a4b6b4..79523459afa 100644
--- a/core/modules/path/tests/src/Functional/PathAliasTest.php
+++ b/core/modules/path/tests/src/Functional/PathAliasTest.php
@@ -7,8 +7,7 @@ use Drupal\Core\Database\Database;
 use Drupal\Core\Url;
 
 /**
- * Add, edit, delete, and change alias and verify its consistency in the
- * database.
+ * Tests modifying path aliases from the UI.
  *
  * @group path
  */
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
index 49db1df5de8..6fd4da3e873 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -24,6 +24,8 @@ use GuzzleHttp\RequestOptions;
 use Psr\Http\Message\ResponseInterface;
 
 /**
+ * Defines a base class for testing all entity resources.
+ *
  * Even though there is the generic EntityResource, it's necessary for every
  * entity type to have its own test, because they each have different fields,
  * validation constraints, et cetera. It's not because the generic case works,
diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php
index 322223ec8ec..98ca2ac7d0c 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeIso8601NormalizerTest.php
@@ -256,6 +256,8 @@ class DateTimeIso8601NormalizerTest extends UnitTestCase {
 }
 
 /**
+ * Provides a test class for testing DrupalDateTime.
+ *
  * Note: Prophecy does not support magic methods. By subclassing and specifying
  * an explicit method, Prophecy works.
  * @see https://github.com/phpspec/prophecy/issues/338
diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeNormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeNormalizerTest.php
index fe503e01a2a..0d270d5e89f 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeNormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/DateTimeNormalizerTest.php
@@ -178,6 +178,8 @@ class DateTimeNormalizerTest extends UnitTestCase {
 
 
 /**
+ * Provides a test class for testing DrupalDateTime.
+ *
  * Note: Prophecy does not support magic methods. By subclassing and specifying
  * an explicit method, Prophecy works.
  * @see https://github.com/phpspec/prophecy/issues/338
diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/TimestampNormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/TimestampNormalizerTest.php
index b1851ab9e1d..750d9d2997a 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/TimestampNormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/TimestampNormalizerTest.php
@@ -133,6 +133,8 @@ class TimestampNormalizerTest extends UnitTestCase {
 }
 
 /**
+ * Provides a test class for testing DrupalDateTime.
+ *
  * Note: Prophecy does not support magic methods. By subclassing and specifying
  * an explicit method, Prophecy works.
  * @see https://github.com/phpspec/prophecy/issues/338
diff --git a/core/modules/statistics/tests/src/Functional/StatisticsTokenReplaceTest.php b/core/modules/statistics/tests/src/Functional/StatisticsTokenReplaceTest.php
index 879f16cc90b..4b81e983f86 100644
--- a/core/modules/statistics/tests/src/Functional/StatisticsTokenReplaceTest.php
+++ b/core/modules/statistics/tests/src/Functional/StatisticsTokenReplaceTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\statistics\Functional;
 use Drupal\Component\Render\FormattableMarkup;
 
 /**
- * Generates text using placeholders for dummy content to check statistics token
- * replacement.
+ * Tests statistics token replacement.
  *
  * @group statistics
  */
diff --git a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php
index 41a9b6d92ab..2e774f31fc2 100644
--- a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php
+++ b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php
@@ -7,8 +7,7 @@ use Drupal\ajax_forms_test\Callbacks;
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- * Form builder: Builds a form that has each FAPI elements triggering a simple
- * Ajax callback.
+ * Builds a form where each Form API element triggers a simple Ajax callback.
  *
  * @internal
  */
diff --git a/core/modules/system/tests/modules/module_install_class_loader_test1/src/EventSubscriber.php b/core/modules/system/tests/modules/module_install_class_loader_test1/src/EventSubscriber.php
index e9e851799f4..5b467532bc4 100644
--- a/core/modules/system/tests/modules/module_install_class_loader_test1/src/EventSubscriber.php
+++ b/core/modules/system/tests/modules/module_install_class_loader_test1/src/EventSubscriber.php
@@ -5,8 +5,10 @@ namespace Drupal\module_install_class_loader_test1;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 
 /**
- * An event subscriber that does different things depending on whether classes
- * exist.
+ * Defines an event subscriber that conditionally unsets the event list.
+ *
+ * @see Drupal\module_install_class_loader_test2\EventSubscriber
+ * @see Drupal\Tests\system\Functional\Module\ClassLoaderTest::testMultipleModules()
  */
 class EventSubscriber implements EventSubscriberInterface {
 
diff --git a/core/modules/system/tests/modules/plugin_test/src/Plugin/plugin_test/mock_block/TypedDataStringBlock.php b/core/modules/system/tests/modules/plugin_test/src/Plugin/plugin_test/mock_block/TypedDataStringBlock.php
index 5658cbf4240..8ddf230930a 100644
--- a/core/modules/system/tests/modules/plugin_test/src/Plugin/plugin_test/mock_block/TypedDataStringBlock.php
+++ b/core/modules/system/tests/modules/plugin_test/src/Plugin/plugin_test/mock_block/TypedDataStringBlock.php
@@ -7,10 +7,10 @@ use Drupal\Core\Plugin\ContextAwarePluginTrait;
 use Drupal\Core\Plugin\PluginBase;
 
 /**
- * Implementation of a String TypedData contextual block plugin used by Plugin
- * API context test.
+ * Implements a String TypedData contextual block plugin.
  *
  * @see \Drupal\plugin_test\Plugin\MockBlockManager
+ * @see \Drupal\KernelTests\Core\Plugin\PluginTestBase
  */
 class TypedDataStringBlock extends PluginBase implements ContextAwarePluginInterface {
 
diff --git a/core/modules/system/tests/src/Functional/Entity/EntityRevisionsTest.php b/core/modules/system/tests/src/Functional/Entity/EntityRevisionsTest.php
index dc355f05a8f..099ae376767 100644
--- a/core/modules/system/tests/src/Functional/Entity/EntityRevisionsTest.php
+++ b/core/modules/system/tests/src/Functional/Entity/EntityRevisionsTest.php
@@ -10,8 +10,7 @@ use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Create a entity with revisions and test viewing, saving, reverting, and
- * deleting revisions.
+ * Tests modifying an entity with revisions.
  *
  * @group Entity
  */
diff --git a/core/modules/system/tests/src/Functional/FileTransfer/FileTransferTest.php b/core/modules/system/tests/src/Functional/FileTransfer/FileTransferTest.php
index 7d6bd2c9d44..9ddd26d9bc2 100644
--- a/core/modules/system/tests/src/Functional/FileTransfer/FileTransferTest.php
+++ b/core/modules/system/tests/src/Functional/FileTransfer/FileTransferTest.php
@@ -7,8 +7,7 @@ use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests that the jail is respected and that protocols using recursive file move
- * operations work.
+ * Tests recursive file copy operations with the file transfer jail.
  *
  * @group FileTransfer
  */
diff --git a/core/modules/system/tests/src/Functional/Form/CheckboxTest.php b/core/modules/system/tests/src/Functional/Form/CheckboxTest.php
index d5aebdb7f48..ed11505859b 100644
--- a/core/modules/system/tests/src/Functional/Form/CheckboxTest.php
+++ b/core/modules/system/tests/src/Functional/Form/CheckboxTest.php
@@ -6,8 +6,9 @@ use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests form API checkbox handling of various combinations of #default_value
- * and #return_value.
+ * Tests the form API checkbox element.
+ *
+ * Various combinations of #default_value and #return_value are used.
  *
  * @group Form
  */
diff --git a/core/modules/system/tests/src/Functional/Form/LanguageSelectElementTest.php b/core/modules/system/tests/src/Functional/Form/LanguageSelectElementTest.php
index 6622ce607c6..26fe1df96ad 100644
--- a/core/modules/system/tests/src/Functional/Form/LanguageSelectElementTest.php
+++ b/core/modules/system/tests/src/Functional/Form/LanguageSelectElementTest.php
@@ -8,8 +8,7 @@ use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests that the language select form element prints and submits the right
- * options.
+ * Tests the language selection form element.
  *
  * @group Form
  */
diff --git a/core/modules/system/tests/src/Functional/Form/StateValuesCleanAdvancedTest.php b/core/modules/system/tests/src/Functional/Form/StateValuesCleanAdvancedTest.php
index b6aea0ead69..90e24029f2e 100644
--- a/core/modules/system/tests/src/Functional/Form/StateValuesCleanAdvancedTest.php
+++ b/core/modules/system/tests/src/Functional/Form/StateValuesCleanAdvancedTest.php
@@ -6,9 +6,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\TestFileCreationTrait;
 
 /**
- * Tests proper removal of submitted form values using
- * \Drupal\Core\Form\FormState::cleanValues() when having forms with elements
- * containing buttons like "managed_file".
+ * Tests the removal of internal Form API elements from submitted form values.
  *
  * @group Form
  */
diff --git a/core/modules/system/tests/src/Functional/Form/StateValuesCleanTest.php b/core/modules/system/tests/src/Functional/Form/StateValuesCleanTest.php
index 473f98ee5ff..4a2fc2a6a09 100644
--- a/core/modules/system/tests/src/Functional/Form/StateValuesCleanTest.php
+++ b/core/modules/system/tests/src/Functional/Form/StateValuesCleanTest.php
@@ -7,8 +7,9 @@ use Drupal\Component\Render\FormattableMarkup;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests proper removal of submitted form values using
- * \Drupal\Core\Form\FormState::cleanValues().
+ * Tests the proper removal of submitted form values.
+ *
+ * @see \Drupal\Core\Form\FormState::cleanValues()
  *
  * @group Form
  */
diff --git a/core/modules/system/tests/src/Functional/Form/StorageTest.php b/core/modules/system/tests/src/Functional/Form/StorageTest.php
index 385ca20392a..9db4723caa4 100644
--- a/core/modules/system/tests/src/Functional/Form/StorageTest.php
+++ b/core/modules/system/tests/src/Functional/Form/StorageTest.php
@@ -7,8 +7,7 @@ use Drupal\Core\EventSubscriber\MainContentViewSubscriber;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests a multistep form using form storage and makes sure validation and
- * caching works right.
+ * Tests a multistep form using form storage.
  *
  * The tested form puts data into the storage during the initial form
  * construction. These tests verify that there are no duplicate form
diff --git a/core/modules/system/tests/src/Functional/System/DateTimeTest.php b/core/modules/system/tests/src/Functional/System/DateTimeTest.php
index 8a587973be6..5ba37320533 100644
--- a/core/modules/system/tests/src/Functional/System/DateTimeTest.php
+++ b/core/modules/system/tests/src/Functional/System/DateTimeTest.php
@@ -7,8 +7,7 @@ use Drupal\Core\Url;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Configure date and time settings. Test date formatting and time zone
- * handling, including daylight saving time.
+ * Test date formatting and time zone handling, including daylight saving time.
  *
  * @group system
  */
diff --git a/core/modules/system/tests/src/Functional/System/ThemeTest.php b/core/modules/system/tests/src/Functional/System/ThemeTest.php
index d512d9320a4..3ae9a3beec7 100644
--- a/core/modules/system/tests/src/Functional/System/ThemeTest.php
+++ b/core/modules/system/tests/src/Functional/System/ThemeTest.php
@@ -9,8 +9,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\TestFileCreationTrait;
 
 /**
- * Tests the theme interface functionality by enabling and switching themes, and
- * using an administration theme.
+ * Tests the theme administration user interface.
  *
  * @group system
  */
diff --git a/core/modules/system/tests/src/Functional/Theme/EntityFilteringThemeTest.php b/core/modules/system/tests/src/Functional/Theme/EntityFilteringThemeTest.php
index e5330bab36b..0e84329a540 100644
--- a/core/modules/system/tests/src/Functional/Theme/EntityFilteringThemeTest.php
+++ b/core/modules/system/tests/src/Functional/Theme/EntityFilteringThemeTest.php
@@ -13,8 +13,7 @@ use Drupal\taxonomy\Entity\Term;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests themed output for each entity type in all available themes to ensure
- * entity labels are filtered for XSS.
+ * Tests XSS filtering for themed output for each entity type in all themes.
  *
  * @group Theme
  */
diff --git a/core/modules/system/tests/src/Functional/Theme/ThemeEarlyInitializationTest.php b/core/modules/system/tests/src/Functional/Theme/ThemeEarlyInitializationTest.php
index a01778dd317..4dab6c2ded1 100644
--- a/core/modules/system/tests/src/Functional/Theme/ThemeEarlyInitializationTest.php
+++ b/core/modules/system/tests/src/Functional/Theme/ThemeEarlyInitializationTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\system\Functional\Theme;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests that the theme system can be correctly initialized early in the page
- * request.
+ * Tests theme system initialization early in the page request.
  *
  * @group Theme
  */
diff --git a/core/modules/system/tests/src/Functional/UpdateSystem/DependencyHookInvocationTest.php b/core/modules/system/tests/src/Functional/UpdateSystem/DependencyHookInvocationTest.php
index d263380924b..561ff795af2 100644
--- a/core/modules/system/tests/src/Functional/UpdateSystem/DependencyHookInvocationTest.php
+++ b/core/modules/system/tests/src/Functional/UpdateSystem/DependencyHookInvocationTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\system\Functional\UpdateSystem;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests that the hook invocation for determining update dependencies works
- * correctly.
+ * Tests the hook invocation for determining update dependencies.
  *
  * @group Update
  */
diff --git a/core/modules/system/tests/src/Functional/UpdateSystem/InvalidUpdateHookTest.php b/core/modules/system/tests/src/Functional/UpdateSystem/InvalidUpdateHookTest.php
index 8412ab1f0e5..0d79aa906d9 100644
--- a/core/modules/system/tests/src/Functional/UpdateSystem/InvalidUpdateHookTest.php
+++ b/core/modules/system/tests/src/Functional/UpdateSystem/InvalidUpdateHookTest.php
@@ -7,8 +7,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\RequirementsPageTrait;
 
 /**
- * Tests that a module implementing hook_update_8000() causes an error to be
- * displayed on update.
+ * Tests that hook_update_8000() is disallowed.
  *
  * @group Update
  */
diff --git a/core/modules/system/tests/src/Functional/UpdateSystem/UpdatesWith7xTest.php b/core/modules/system/tests/src/Functional/UpdateSystem/UpdatesWith7xTest.php
index e12b5868731..2364e99bdd8 100644
--- a/core/modules/system/tests/src/Functional/UpdateSystem/UpdatesWith7xTest.php
+++ b/core/modules/system/tests/src/Functional/UpdateSystem/UpdatesWith7xTest.php
@@ -7,8 +7,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\RequirementsPageTrait;
 
 /**
- * Tests that the minimum schema version is correct even if only 7.x update
- * hooks are retained .
+ * Tests the minimum schema version when only 7.x update hooks are retained.
  *
  * @group Update
  */
diff --git a/core/modules/system/tests/src/Kernel/Common/UrlTest.php b/core/modules/system/tests/src/Kernel/Common/UrlTest.php
index 6ed9d626e3f..22791a7a853 100644
--- a/core/modules/system/tests/src/Kernel/Common/UrlTest.php
+++ b/core/modules/system/tests/src/Kernel/Common/UrlTest.php
@@ -12,11 +12,10 @@ use Drupal\Core\Url;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Confirm that \Drupal\Core\Url,
- * \Drupal\Component\Utility\UrlHelper::filterQueryParameters(),
- * \Drupal\Component\Utility\UrlHelper::buildQuery(), and
- * \Drupal\Core\Utility\LinkGeneratorInterface::generate()
- * work correctly with various input.
+ * Tests the Url object.
+ *
+ * @covers \Drupal\Component\Utility\UrlHelper::filterQueryParameters()
+ * @covers \Drupal\Core\Utility\LinkGeneratorInterface::generate()
  *
  * @group Common
  */
diff --git a/core/modules/system/tests/src/Kernel/Token/TokenReplaceKernelTest.php b/core/modules/system/tests/src/Kernel/Token/TokenReplaceKernelTest.php
index 06fa062ddd5..2ecff8dcbe6 100644
--- a/core/modules/system/tests/src/Kernel/Token/TokenReplaceKernelTest.php
+++ b/core/modules/system/tests/src/Kernel/Token/TokenReplaceKernelTest.php
@@ -10,8 +10,7 @@ use Drupal\Core\Render\BubbleableMetadata;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
- * Generates text using placeholders for dummy content to check token
- * replacement.
+ * Tests token replacement.
  *
  * @group system
  */
diff --git a/core/modules/taxonomy/tests/src/Functional/RssTest.php b/core/modules/taxonomy/tests/src/Functional/RssTest.php
index 6558da83183..9b434d12928 100644
--- a/core/modules/taxonomy/tests/src/Functional/RssTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/RssTest.php
@@ -6,8 +6,7 @@ use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\views\Views;
 
 /**
- * Ensure that data added as terms appears in RSS feeds if "RSS Category" format
- * is selected.
+ * Tests the taxonomy RSS display.
  *
  * @group taxonomy
  */
diff --git a/core/modules/taxonomy/tests/src/Functional/TokenReplaceTest.php b/core/modules/taxonomy/tests/src/Functional/TokenReplaceTest.php
index 383853ab28c..87e2811af9d 100644
--- a/core/modules/taxonomy/tests/src/Functional/TokenReplaceTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/TokenReplaceTest.php
@@ -6,8 +6,7 @@ use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\Core\Render\BubbleableMetadata;
 
 /**
- * Generates text using placeholders for dummy content to check taxonomy token
- * replacement.
+ * Tests taxonomy token replacement.
  *
  * @group taxonomy
  */
diff --git a/core/modules/update/tests/src/Functional/UpdateContribTest.php b/core/modules/update/tests/src/Functional/UpdateContribTest.php
index 20a0d5eda32..294074c592e 100644
--- a/core/modules/update/tests/src/Functional/UpdateContribTest.php
+++ b/core/modules/update/tests/src/Functional/UpdateContribTest.php
@@ -6,8 +6,7 @@ use Drupal\Core\Utility\ProjectInfo;
 use Drupal\update\UpdateManagerInterface;
 
 /**
- * Tests how the Update Manager module handles contributed modules and themes in
- * a series of functional tests using mock XML data.
+ * Tests how the Update Manager handles contributed modules and themes.
  *
  * @group update
  */
diff --git a/core/modules/update/tests/src/Functional/UpdateSemverCoreTest.php b/core/modules/update/tests/src/Functional/UpdateSemverCoreTest.php
index d740425fbd6..829b68dd7b3 100644
--- a/core/modules/update/tests/src/Functional/UpdateSemverCoreTest.php
+++ b/core/modules/update/tests/src/Functional/UpdateSemverCoreTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\update\Functional;
 use Drupal\Core\Url;
 
 /**
- * Tests the Update Manager module through a series of functional tests using
- * mock XML data.
+ * Tests the semantic version handling in the Update Manager.
  *
  * @group update
  */
diff --git a/core/modules/user/tests/src/Functional/UserLanguageCreationTest.php b/core/modules/user/tests/src/Functional/UserLanguageCreationTest.php
index 94d86b492a7..4f3478542ae 100644
--- a/core/modules/user/tests/src/Functional/UserLanguageCreationTest.php
+++ b/core/modules/user/tests/src/Functional/UserLanguageCreationTest.php
@@ -6,8 +6,7 @@ use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests whether proper language is stored for new users and access to language
- * selector.
+ * Tests preferred language configuration and language selector access.
  *
  * @group user
  */
diff --git a/core/modules/user/tests/src/Functional/UserPermissionsTest.php b/core/modules/user/tests/src/Functional/UserPermissionsTest.php
index 1c5be8689d0..c79c470d8c8 100644
--- a/core/modules/user/tests/src/Functional/UserPermissionsTest.php
+++ b/core/modules/user/tests/src/Functional/UserPermissionsTest.php
@@ -7,8 +7,7 @@ use Drupal\user\RoleInterface;
 use Drupal\user\Entity\Role;
 
 /**
- * Verify that role permissions can be added and removed via the permissions
- * pages.
+ * Verifies role permissions can be added and removed via the permissions page.
  *
  * @group user
  */
diff --git a/core/modules/user/tests/src/Functional/UserSearchTest.php b/core/modules/user/tests/src/Functional/UserSearchTest.php
index 973dc260266..5c013cdbfd1 100644
--- a/core/modules/user/tests/src/Functional/UserSearchTest.php
+++ b/core/modules/user/tests/src/Functional/UserSearchTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\user\Functional;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests the user search page and verifies that sensitive information is hidden
- * from unauthorized users.
+ * Verifies that sensitive information is hidden from unauthorized users.
  *
  * @group user
  */
diff --git a/core/modules/user/tests/src/Functional/UserTokenReplaceTest.php b/core/modules/user/tests/src/Functional/UserTokenReplaceTest.php
index 2649f7a8f0b..2857268a253 100644
--- a/core/modules/user/tests/src/Functional/UserTokenReplaceTest.php
+++ b/core/modules/user/tests/src/Functional/UserTokenReplaceTest.php
@@ -9,8 +9,7 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\user\Entity\User;
 
 /**
- * Generates text using placeholders for dummy content to check user token
- * replacement.
+ * Tests the replacement of user tokens.
  *
  * @group user
  */
diff --git a/core/modules/user/tests/src/Kernel/UserAccountFormFieldsTest.php b/core/modules/user/tests/src/Kernel/UserAccountFormFieldsTest.php
index 1aabea79a8a..dbc61853452 100644
--- a/core/modules/user/tests/src/Kernel/UserAccountFormFieldsTest.php
+++ b/core/modules/user/tests/src/Kernel/UserAccountFormFieldsTest.php
@@ -6,8 +6,7 @@ use Drupal\Core\Form\FormState;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Verifies that the field order in user account forms is compatible with
- * password managers of web browsers.
+ * Verifies the field order in user account forms.
  *
  * @group user
  */
diff --git a/core/modules/user/tests/src/Kernel/UserActionConfigSchemaTest.php b/core/modules/user/tests/src/Kernel/UserActionConfigSchemaTest.php
index 527db24aa41..8767c92e159 100644
--- a/core/modules/user/tests/src/Kernel/UserActionConfigSchemaTest.php
+++ b/core/modules/user/tests/src/Kernel/UserActionConfigSchemaTest.php
@@ -7,8 +7,7 @@ use Drupal\KernelTests\KernelTestBase;
 use Drupal\user\Entity\Role;
 
 /**
- * Ensures the user action for adding and removing roles have valid config
- * schema.
+ * Tests that the config schema is valid when roles are added or removed.
  *
  * @group user
  */
diff --git a/core/modules/user/tests/src/Traits/UserCreationTrait.php b/core/modules/user/tests/src/Traits/UserCreationTrait.php
index 92a3101e181..683ba355c8a 100644
--- a/core/modules/user/tests/src/Traits/UserCreationTrait.php
+++ b/core/modules/user/tests/src/Traits/UserCreationTrait.php
@@ -13,8 +13,7 @@ use Drupal\user\Entity\User;
 use Drupal\user\RoleInterface;
 
 /**
- * Provides methods to create additional test users and switch the currently
- * logged in one.
+ * Provides test methods for user creation and authentication.
  *
  * This trait is meant to be used only by test classes.
  */
diff --git a/core/modules/views/tests/src/Functional/Wizard/ItemsPerPageTest.php b/core/modules/views/tests/src/Functional/Wizard/ItemsPerPageTest.php
index da9ac54e063..61da043cf2d 100644
--- a/core/modules/views/tests/src/Functional/Wizard/ItemsPerPageTest.php
+++ b/core/modules/views/tests/src/Functional/Wizard/ItemsPerPageTest.php
@@ -3,8 +3,7 @@
 namespace Drupal\Tests\views\Functional\Wizard;
 
 /**
- * Tests the ability of the views wizard to specify the number of items per
- * page.
+ * Tests that the views wizard can specify the number of items per page.
  *
  * @group views
  */
diff --git a/core/modules/views/tests/src/Kernel/Handler/FilterBooleanOperatorStringTest.php b/core/modules/views/tests/src/Kernel/Handler/FilterBooleanOperatorStringTest.php
index 88c3de207aa..66bac02a642 100644
--- a/core/modules/views/tests/src/Kernel/Handler/FilterBooleanOperatorStringTest.php
+++ b/core/modules/views/tests/src/Kernel/Handler/FilterBooleanOperatorStringTest.php
@@ -6,8 +6,7 @@ use Drupal\Tests\views\Kernel\ViewsKernelTestBase;
 use Drupal\views\Views;
 
 /**
- * Tests the core Drupal\views\Plugin\views\filter\BooleanOperatorString
- * handler.
+ * Tests core's BooleanOperatorString views filter handler.
  *
  * @group views
  * @see \Drupal\views\Plugin\views\filter\BooleanOperatorString
diff --git a/core/profiles/testing/modules/drupal_system_listing_compatible_test/tests/src/Kernel/SystemListingCrossProfileCompatibleTest.php b/core/profiles/testing/modules/drupal_system_listing_compatible_test/tests/src/Kernel/SystemListingCrossProfileCompatibleTest.php
index d3a9f0d7e8a..cc4ec230e12 100644
--- a/core/profiles/testing/modules/drupal_system_listing_compatible_test/tests/src/Kernel/SystemListingCrossProfileCompatibleTest.php
+++ b/core/profiles/testing/modules/drupal_system_listing_compatible_test/tests/src/Kernel/SystemListingCrossProfileCompatibleTest.php
@@ -5,8 +5,7 @@ namespace Drupal\Tests\drupal_system_listing_compatible_test\Kernel;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Verifies that tests in installation profile modules are found and may use
- * another profile for running tests.
+ * Verifies that tests in installation profile modules are found.
  *
  * @group drupal_system_listing_compatible_test
  */
diff --git a/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MultiFormTest.php b/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MultiFormTest.php
index 83c26e96e1a..d436179b414 100644
--- a/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MultiFormTest.php
+++ b/core/tests/Drupal/FunctionalJavascriptTests/Ajax/MultiFormTest.php
@@ -8,8 +8,7 @@ use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
 
 /**
- * Tests that AJAX-enabled forms work when multiple instances of the same form
- * are on a page.
+ * Tests AJAX-enabled forms when multiple instances of the form are on a page.
  *
  * @group Ajax
  */
diff --git a/core/tests/Drupal/FunctionalTests/FolderTest.php b/core/tests/Drupal/FunctionalTests/FolderTest.php
index a8196ebd925..923849e561c 100644
--- a/core/tests/Drupal/FunctionalTests/FolderTest.php
+++ b/core/tests/Drupal/FunctionalTests/FolderTest.php
@@ -5,8 +5,8 @@ namespace Drupal\FunctionalTests;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * This test will check BrowserTestBase's treatment of hook_install during
- * setUp.
+ * Tests BrowserTestBase's treatment of hook_install() during setup.
+ *
  * Image module is used for test.
  *
  * @group browsertestbase
diff --git a/core/tests/Drupal/FunctionalTests/Installer/InstallerExistingDatabaseSettingsTest.php b/core/tests/Drupal/FunctionalTests/Installer/InstallerExistingDatabaseSettingsTest.php
index ee6caea944f..53a615b57cd 100644
--- a/core/tests/Drupal/FunctionalTests/Installer/InstallerExistingDatabaseSettingsTest.php
+++ b/core/tests/Drupal/FunctionalTests/Installer/InstallerExistingDatabaseSettingsTest.php
@@ -5,8 +5,7 @@ namespace Drupal\FunctionalTests\Installer;
 use Drupal\Core\Database\Database;
 
 /**
- * Tests the installer with an existing settings file with database connection
- * info.
+ * Tests installation with database information in an existing settings file.
  *
  * @group Installer
  */
diff --git a/core/tests/Drupal/FunctionalTests/Installer/InstallerSiteConfigProfileTest.php b/core/tests/Drupal/FunctionalTests/Installer/InstallerSiteConfigProfileTest.php
index 097d8451891..c09bf838e4e 100644
--- a/core/tests/Drupal/FunctionalTests/Installer/InstallerSiteConfigProfileTest.php
+++ b/core/tests/Drupal/FunctionalTests/Installer/InstallerSiteConfigProfileTest.php
@@ -3,8 +3,7 @@
 namespace Drupal\FunctionalTests\Installer;
 
 /**
- * Verifies that the installer defaults to the existing site email address and
- * timezone, if they were provided by the install profile.
+ * Verifies that the installer uses the profile's site configuration.
  *
  * @group Installer
  */
diff --git a/core/tests/Drupal/FunctionalTests/MailCaptureTest.php b/core/tests/Drupal/FunctionalTests/MailCaptureTest.php
index d4bc642e714..67f0099704f 100644
--- a/core/tests/Drupal/FunctionalTests/MailCaptureTest.php
+++ b/core/tests/Drupal/FunctionalTests/MailCaptureTest.php
@@ -7,8 +7,10 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Core\Test\AssertMailTrait;
 
 /**
- * Tests the email capturing logic, the assertMail assertion and the
- * drupalGetMails function.
+ * Tests the collection of emails during testing.
+ *
+ * The test mail collector, test.mail.collector, intercepts any email sent
+ * during a test so it does not leave the test server.
  *
  * @group browsertestbase
  */
diff --git a/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php b/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php
index f595cfcab5e..77e70784ee3 100644
--- a/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php
@@ -6,8 +6,7 @@ use Drupal\Component\Utility\Bytes;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Parse a predefined amount of bytes and compare the output with the expected
- * value.
+ * Tests format_size().
  *
  * @group Common
  */
diff --git a/core/tests/Drupal/KernelTests/Core/Common/XssUnitTest.php b/core/tests/Drupal/KernelTests/Core/Common/XssUnitTest.php
index ff7fba57ffa..38edb98d36a 100644
--- a/core/tests/Drupal/KernelTests/Core/Common/XssUnitTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Common/XssUnitTest.php
@@ -6,8 +6,11 @@ use Drupal\Component\Utility\UrlHelper;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Confirm that \Drupal\Component\Utility\Xss::filter() and check_url() work
- * correctly, including invalid multi-byte sequences.
+ * Tests XSS filtering.
+ *
+ * @see \Drupal\Component\Utility\Xss::filter()
+ * @see \Drupal\Component\Utility\UrlHelper::filterBadProtocol
+ * @see \Drupal\Component\Utility\UrlHelper::stripDangerousProtocols
  *
  * @group Common
  */
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStorageTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStorageTest.php
index 91887ecc59e..325d5cd66a5 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStorageTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigEntityStorageTest.php
@@ -6,8 +6,7 @@ use Drupal\Core\Config\ConfigDuplicateUUIDException;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Tests sync and importing config entities with IDs and UUIDs that match
- * existing config.
+ * Tests configuration entity storage.
  *
  * @group config
  */
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigOverridesPriorityTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigOverridesPriorityTest.php
index 7ad4487796e..b5ca02e9561 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigOverridesPriorityTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigOverridesPriorityTest.php
@@ -6,8 +6,13 @@ use Drupal\Core\Language\Language;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Tests that language, module and settings.php are applied in the correct
- * order.
+ * Tests that config overrides are applied in the correct order.
+ *
+ * Overrides should be applied in the following order, from lowest priority
+ * to highest:
+ * - Language overrides.
+ * - Module overrides.
+ * - settings.php overrides.
  *
  * @group config
  */
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityCrudHookTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityCrudHookTest.php
index 3cd38553131..ff9c257fb42 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityCrudHookTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityCrudHookTest.php
@@ -16,6 +16,8 @@ use Drupal\user\Entity\User;
 use Drupal\file\Entity\File;
 
 /**
+ * Tests entity CRUD via hooks.
+ *
  * Tests the invocation of hooks when creating, inserting, loading, updating or
  * deleting an entity.
  *
diff --git a/core/tests/Drupal/KernelTests/Core/File/FileTestBase.php b/core/tests/Drupal/KernelTests/Core/File/FileTestBase.php
index fe523eecf07..ac0376d6962 100644
--- a/core/tests/Drupal/KernelTests/Core/File/FileTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/File/FileTestBase.php
@@ -6,8 +6,7 @@ use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Base class for file tests that adds some additional file specific
- * assertions and helper functions.
+ * Provides file-specific assertions and helper functions.
  */
 abstract class FileTestBase extends KernelTestBase {
 
diff --git a/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php b/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php
index 9d89caa87ab..fe8d614c88a 100644
--- a/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Form/FormCacheTest.php
@@ -9,8 +9,10 @@ use Drupal\Core\Site\Settings;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Tests \Drupal::formBuilder()->setCache() and
- * \Drupal::formBuilder()->getCache().
+ * Tests FormBuilder caching.
+ *
+ * @covers \Drupal\Core\Form\FormBuilder::getCache
+ * @covers \Drupal\Core\Form\FormBuilder::setCache
  *
  * @group Form
  */
diff --git a/core/tests/Drupal/KernelTests/Core/Plugin/Condition/RequestPathTest.php b/core/tests/Drupal/KernelTests/Core/Plugin/Condition/RequestPathTest.php
index be6ec023eeb..efbbd9113ef 100644
--- a/core/tests/Drupal/KernelTests/Core/Plugin/Condition/RequestPathTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Plugin/Condition/RequestPathTest.php
@@ -9,8 +9,7 @@ use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\RequestStack;
 
 /**
- * Tests that the Request Path Condition, provided by the system module, is
- * working properly.
+ * Tests system.module's request path condition.
  *
  * @group Plugin
  */
diff --git a/core/tests/Drupal/KernelTests/Core/Plugin/Discovery/CustomDirectoryAnnotatedClassDiscoveryTest.php b/core/tests/Drupal/KernelTests/Core/Plugin/Discovery/CustomDirectoryAnnotatedClassDiscoveryTest.php
index 48f987decce..c65f0e14f0e 100644
--- a/core/tests/Drupal/KernelTests/Core/Plugin/Discovery/CustomDirectoryAnnotatedClassDiscoveryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Plugin/Discovery/CustomDirectoryAnnotatedClassDiscoveryTest.php
@@ -6,8 +6,7 @@ use Drupal\Core\Plugin\Discovery\AnnotatedClassDiscovery;
 use Drupal\Core\StringTranslation\TranslatableMarkup;
 
 /**
- * Tests that plugins in a custom directory are correctly discovered using
- * annotated classes.
+ * Tests discovery of annotated plugins in a custom directory.
  *
  * @group Plugin
  */
diff --git a/core/tests/Drupal/KernelTests/Core/TypedData/ComplexDataConstraintValidatorTest.php b/core/tests/Drupal/KernelTests/Core/TypedData/ComplexDataConstraintValidatorTest.php
index 94b1b33aa93..0d9d06d7971 100644
--- a/core/tests/Drupal/KernelTests/Core/TypedData/ComplexDataConstraintValidatorTest.php
+++ b/core/tests/Drupal/KernelTests/Core/TypedData/ComplexDataConstraintValidatorTest.php
@@ -7,8 +7,7 @@ use Drupal\Core\TypedData\MapDataDefinition;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * Tests ComplexData validation constraint with both valid and invalid values
- * for a key.
+ * Tests ComplexData validation with both valid and invalid values.
  *
  * @group Validation
  */