diff --git a/core/modules/jsonapi/tests/src/Functional/CommentTest.php b/core/modules/jsonapi/tests/src/Functional/CommentTest.php
index 28660453180..4faf84fd3ff 100644
--- a/core/modules/jsonapi/tests/src/Functional/CommentTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/CommentTest.php
@@ -383,7 +383,7 @@ class CommentTest extends ResourceTestBase {
   /**
    * {@inheritdoc}
    */
-  public function testPatchIndividual(): void {
+  protected function doTestPatchIndividual(): void {
     // Ensure ::getModifiedEntityForPatchTesting() can pick an alternative value
     // for the 'entity_id' field.
     EntityTest::create([
@@ -391,7 +391,7 @@ class CommentTest extends ResourceTestBase {
       'type' => 'bar',
     ])->save();
 
-    parent::testPatchIndividual();
+    parent::doTestPatchIndividual();
   }
 
 }
diff --git a/core/modules/jsonapi/tests/src/Functional/FileTest.php b/core/modules/jsonapi/tests/src/Functional/FileTest.php
index 899bcbdc78f..22635e56d7e 100644
--- a/core/modules/jsonapi/tests/src/Functional/FileTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/FileTest.php
@@ -201,11 +201,16 @@ class FileTest extends ResourceTestBase {
   }
 
   /**
-   * {@inheritdoc}
+   * Tests POST/PATCH/DELETE for an individual resource.
    */
-  public function testPostIndividual(): void {
+  public function testIndividual(): void {
     // @todo https://www.drupal.org/node/1927648
-    $this->markTestSkipped();
+    // Add doTestPostIndividual().
+    $this->doTestPatchIndividual();
+    $this->entity = $this->resaveEntity($this->entity, $this->account);
+    $this->revokePermissions();
+    $this->config('jsonapi.settings')->set('read_only', TRUE)->save(TRUE);
+    $this->doTestDeleteIndividual();
   }
 
   /**
diff --git a/core/modules/jsonapi/tests/src/Functional/FileUploadTest.php b/core/modules/jsonapi/tests/src/Functional/FileUploadTest.php
index 139531bb80a..b782e6d09c3 100644
--- a/core/modules/jsonapi/tests/src/Functional/FileUploadTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/FileUploadTest.php
@@ -113,7 +113,7 @@ class FileUploadTest extends ResourceTestBase {
    *
    * @var array
    */
-  const SKIP_METHODS = ['testGetIndividual', 'testPostIndividual', 'testPatchIndividual', 'testDeleteIndividual', 'testCollection', 'testRelationships'];
+  const SKIP_METHODS = ['testGetIndividual', 'testIndividual', 'testCollection', 'testRelationships'];
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/jsonapi/tests/src/Functional/MediaTest.php b/core/modules/jsonapi/tests/src/Functional/MediaTest.php
index e733e773bc4..f74bf01c76f 100644
--- a/core/modules/jsonapi/tests/src/Functional/MediaTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/MediaTest.php
@@ -360,10 +360,10 @@ class MediaTest extends ResourceTestBase {
   /**
    * {@inheritdoc}
    */
-  public function testPostIndividual(): void {
+  protected function doTestPostIndividual(): void {
     // @todo Mimic \Drupal\Tests\rest\Functional\EntityResource\Media\MediaResourceTestBase::testPost()
     // @todo Later, use https://www.drupal.org/project/drupal/issues/2958554 to upload files rather than the REST module.
-    parent::testPostIndividual();
+    parent::doTestPostIndividual();
   }
 
   /**
diff --git a/core/modules/jsonapi/tests/src/Functional/MessageTest.php b/core/modules/jsonapi/tests/src/Functional/MessageTest.php
index ed23715b073..629aa8bfd1c 100644
--- a/core/modules/jsonapi/tests/src/Functional/MessageTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/MessageTest.php
@@ -132,7 +132,7 @@ class MessageTest extends ResourceTestBase {
   /**
    * {@inheritdoc}
    */
-  public function testPatchIndividual(): void {
+  protected function doTestPatchIndividual(): void {
     // Contact Message entities are not stored, so they cannot be modified.
     $this->expectException(RouteNotFoundException::class);
     $this->expectExceptionMessage('Route "jsonapi.contact_message--camelids.individual" does not exist.');
@@ -143,7 +143,7 @@ class MessageTest extends ResourceTestBase {
   /**
    * {@inheritdoc}
    */
-  public function testDeleteIndividual(): void {
+  protected function doTestDeleteIndividual(): void {
     // Contact Message entities are not stored, so they cannot be deleted.
     $this->expectException(RouteNotFoundException::class);
     $this->expectExceptionMessage('Route "jsonapi.contact_message--camelids.individual" does not exist.');
diff --git a/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php b/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php
index 5960ca8a895..1b84fe615e9 100644
--- a/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php
+++ b/core/modules/jsonapi/tests/src/Functional/ResourceTestBase.php
@@ -229,21 +229,7 @@ abstract class ResourceTestBase extends BrowserTestBase {
 
     $this->config('system.logging')->set('error_level', ERROR_REPORTING_HIDE)->save();
 
-    // Ensure the anonymous user role has no permissions at all.
-    $user_role = Role::load(RoleInterface::ANONYMOUS_ID);
-    foreach ($user_role->getPermissions() as $permission) {
-      $user_role->revokePermission($permission);
-    }
-    $user_role->save();
-    assert([] === $user_role->getPermissions(), 'The anonymous user role has no permissions at all.');
-
-    // Ensure the authenticated user role has no permissions at all.
-    $user_role = Role::load(RoleInterface::AUTHENTICATED_ID);
-    foreach ($user_role->getPermissions() as $permission) {
-      $user_role->revokePermission($permission);
-    }
-    $user_role->save();
-    assert([] === $user_role->getPermissions(), 'The authenticated user role has no permissions at all.');
+    $this->revokePermissions();
 
     // Create an account, which tests will use. Also ensure the @current_user
     // service this account, to ensure certain access check logic in tests works
@@ -338,12 +324,15 @@ abstract class ResourceTestBase extends BrowserTestBase {
 
     \Drupal::service('router.builder')->rebuildIfNeeded();
 
+    return $this->resaveEntity($entity, $account);
+  }
+
+  protected function resaveEntity(EntityInterface $entity, AccountInterface $account): EntityInterface {
     // Reload entity so that it has the new field.
     $reloaded_entity = $this->entityLoadUnchanged($entity->id());
     // Some entity types are not stored, hence they cannot be reloaded.
     if ($reloaded_entity !== NULL) {
       $entity = $reloaded_entity;
-
       // Set a default value on the fields.
       $entity->set('field_rest_test', ['value' => 'All the faith he had had had had no effect on the outcome of his life.']);
       $entity->set('field_jsonapi_test_entity_ref', ['user' => $account->id()]);
@@ -1973,10 +1962,25 @@ abstract class ResourceTestBase extends BrowserTestBase {
     return $related_response;
   }
 
+  /**
+   * Tests POST/PATCH/DELETE for an individual resource.
+   */
+  public function testIndividual(): void {
+    $this->doTestPostIndividual();
+    $this->entity = $this->resaveEntity($this->entity, $this->account);
+    $this->revokePermissions();
+    $this->config('jsonapi.settings')->set('read_only', TRUE)->save(TRUE);
+    $this->doTestPatchIndividual();
+    $this->entity = $this->resaveEntity($this->entity, $this->account);
+    $this->revokePermissions();
+    $this->config('jsonapi.settings')->set('read_only', TRUE)->save(TRUE);
+    $this->doTestDeleteIndividual();
+  }
+
   /**
    * Tests POSTing an individual resource, plus edge cases to ensure good DX.
    */
-  public function testPostIndividual(): void {
+  protected function doTestPostIndividual(): void {
     // @todo Remove this in https://www.drupal.org/node/2300677.
     if ($this->entity instanceof ConfigEntityInterface) {
       $this->markTestSkipped('POSTing config entities is not yet supported.');
@@ -2191,7 +2195,7 @@ abstract class ResourceTestBase extends BrowserTestBase {
   /**
    * Tests PATCHing an individual resource, plus edge cases to ensure good DX.
    */
-  public function testPatchIndividual(): void {
+  protected function doTestPatchIndividual(): void {
     // @todo Remove this in https://www.drupal.org/node/2300677.
     if ($this->entity instanceof ConfigEntityInterface) {
       $this->markTestSkipped('PATCHing config entities is not yet supported.');
@@ -2519,7 +2523,7 @@ abstract class ResourceTestBase extends BrowserTestBase {
   /**
    * Tests DELETEing an individual resource, plus edge cases to ensure good DX.
    */
-  public function testDeleteIndividual(): void {
+  protected function doTestDeleteIndividual(): void {
     // @todo Remove this in https://www.drupal.org/node/2300677.
     if ($this->entity instanceof ConfigEntityInterface) {
       $this->markTestSkipped('DELETEing config entities is not yet supported.');
@@ -3574,4 +3578,23 @@ abstract class ResourceTestBase extends BrowserTestBase {
     return $expected_document;
   }
 
+  /**
+   * Ensure the anonymous and authenticated roles have no permissions at all.
+   */
+  protected function revokePermissions(): void {
+    $user_role = Role::load(RoleInterface::ANONYMOUS_ID);
+    foreach ($user_role->getPermissions() as $permission) {
+      $user_role->revokePermission($permission);
+    }
+    $user_role->save();
+    assert([] === $user_role->getPermissions(), 'The anonymous user role has no permissions at all.');
+
+    $user_role = Role::load(RoleInterface::AUTHENTICATED_ID);
+    foreach ($user_role->getPermissions() as $permission) {
+      $user_role->revokePermission($permission);
+    }
+    $user_role->save();
+    assert([] === $user_role->getPermissions(), 'The authenticated user role has no permissions at all.');
+  }
+
 }
diff --git a/core/modules/jsonapi/tests/src/Functional/UserTest.php b/core/modules/jsonapi/tests/src/Functional/UserTest.php
index 7231798f6f9..c2d177b56a8 100644
--- a/core/modules/jsonapi/tests/src/Functional/UserTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/UserTest.php
@@ -128,10 +128,10 @@ class UserTest extends ResourceTestBase {
   /**
    * {@inheritdoc}
    */
-  public function testDeleteIndividual(): void {
+  protected function doTestDeleteIndividual(): void {
     $this->config('user.settings')->set('cancel_method', 'user_cancel_delete')->save(TRUE);
 
-    parent::testDeleteIndividual();
+    parent::doTestDeleteIndividual();
   }
 
   /**
@@ -195,6 +195,21 @@ class UserTest extends ResourceTestBase {
     ];
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function getPatchDocument() {
+    return [
+      'data' => [
+        'id' => $this->entity->uuid(),
+        'type' => 'user--user',
+        'attributes' => [
+          'name' => 'Drama llama 2',
+        ],
+      ],
+    ];
+  }
+
   /**
    * {@inheritdoc}
    */