Issue #2960054 by Sam152:...

Issue #2960054 by Sam152: content_moderation_post_update_update_cms_default_revisions fails if content_moderation was enabled but no entity types were being moderated

core/modules/content_moderation/content_moderation.post_update.php

@@ -20,6 +20,7 @@ function content_moderation_post_update_update_cms_default_revisions(&$sandbox)
   $entity_type_id = &$sandbox['entity_type_id'];
   if (!isset($entity_type_id)) {
     $sandbox['bundles'] = [];
+    $sandbox['entity_type_ids'] = [];
     /** @var \Drupal\workflows\WorkflowInterface $workflow */
     foreach (Workflow::loadMultipleByType('content_moderation') as $workflow) {
       /** @var \Drupal\content_moderation\Plugin\WorkflowType\ContentModeration $plugin */

core/modules/content_moderation/tests/src/Functional/DefaultContentModerationStateRevisionUpdateTest.php

@@ -20,7 +20,6 @@ protected function setDatabaseDumpFiles() {
     $this->databaseDumpFiles = [
       __DIR__ . '/../../../../system/tests/fixtures/update/drupal-8.4.0.bare.standard.php.gz',
       __DIR__ . '/../../fixtures/update/drupal-8.4.0-content_moderation_installed.php',
-      __DIR__ . '/../../fixtures/update/drupal-8.default-cms-entity-id-2941736.php',
     ];
   }
 
@@ -28,6 +27,11 @@ protected function setDatabaseDumpFiles() {
    * Test updating the default revision.
    */
   public function testUpdateDefaultRevision() {
+    // Include the database fixture required to test updating the default
+    // revision. This is excluded from  ::setDatabaseDumpFiles so that we can
+    // test the same post_update hook with no test content enabled.
+    require __DIR__ . '/../../fixtures/update/drupal-8.default-cms-entity-id-2941736.php';
+
     $this->runUpdates();
 
     foreach (['node', 'block_content'] as $entity_type_id) {
@@ -45,6 +49,14 @@ public function testUpdateDefaultRevision() {
     }
   }
 
+  /**
+   * Test the post_update hook when no entity types are being moderated.
+   */
+  public function testNoEntitiesUnderModeration() {
+    // If any errors occur during the post_update hook, the test case will fail.
+    $this->runUpdates();
+  }
+
   /**
    * Assert for the given entity, the default revision ID matches.
    *