diff --git a/core/modules/migrate_drupal/tests/src/Traits/CreateTestContentEntitiesTrait.php b/core/modules/migrate_drupal/tests/src/Traits/CreateTestContentEntitiesTrait.php
index 81e2064..551e721 100644
--- a/core/modules/migrate_drupal/tests/src/Traits/CreateTestContentEntitiesTrait.php
+++ b/core/modules/migrate_drupal/tests/src/Traits/CreateTestContentEntitiesTrait.php
@@ -60,11 +60,11 @@ protected function installEntitySchemas() {
    * Create several pieces of generic content.
    */
   protected function createContent() {
-    $entityTypeManager = \Drupal::entityTypeManager();
+    $entity_type_manager = \Drupal::entityTypeManager();
 
     // Create an aggregator feed.
-    if ($entityTypeManager->hasDefinition('aggregator_feed')) {
-      $feed = Feed::create([
+    if ($entity_type_manager->hasDefinition('aggregator_feed')) {
+      $feed = $entity_type_manager->getStorage('aggregator_feed')->create([
         'title' => 'feed',
         'url' => 'http://www.example.com',
       ]);
@@ -72,8 +72,8 @@ protected function createContent() {
     }
 
     // Create an aggregator feed item.
-    if ($entityTypeManager->hasDefinition('aggregator_item')) {
-      $item = Item::create([
+    if ($feed->id() && $entity_type_manager->hasDefinition('aggregator_item')) {
+      $item = $entity_type_manager->getStorage('aggregator_item')->create([
         'title' => 'feed item',
         'fid' => $feed->id(),
         'link' => 'http://www.example.com',
@@ -82,8 +82,8 @@ protected function createContent() {
     }
 
     // Create a block content.
-    if ($entityTypeManager->hasDefinition('block_content')) {
-      $block = BlockContent::create([
+    if ($entity_type_manager->hasDefinition('block_content')) {
+      $block = $entity_type_manager->getStorage('aggregator_item')->create([
         'info' => 'block',
         'type' => 'block',
       ]);
@@ -91,8 +91,8 @@ protected function createContent() {
     }
 
     // Create a node.
-    if ($entityTypeManager->hasDefinition('node')) {
-      $node = Node::create([
+    if ($entity_type_manager->hasDefinition('node')) {
+      $node = $entity_type_manager->getStorage('aggregator_item')->create([
         'type' => 'page',
         'title' => 'page',
       ]);
@@ -100,8 +100,8 @@ protected function createContent() {
     }
 
     // Create a comment.
-    if ($entityTypeManager->hasDefinition('comment')) {
-      $comment = Comment::create([
+    if ($entity_type_manager->hasDefinition('comment')) {
+      $comment = $entity_type_manager->getStorage('aggregator_item')->create([
         'comment_type' => 'comment',
         'field_name' => 'comment',
         'entity_type' => 'node',
@@ -111,16 +111,16 @@ protected function createContent() {
     }
 
     // Create a file.
-    if ($entityTypeManager->hasDefinition('file')) {
-      $file = File::create([
+    if ($entity_type_manager->hasDefinition('file')) {
+      $file = $entity_type_manager->getStorage('aggregator_item')->create([
         'uri' => 'public://example.txt',
       ]);
       $file->save();
     }
 
     // Create a menu link.
-    if ($entityTypeManager->hasDefinition('menu_link_content')) {
-      $menu_link = MenuLinkContent::create([
+    if ($entity_type_manager->hasDefinition('menu_link_content')) {
+      $menu_link = $entity_type_manager->getStorage('aggregator_item')->create([
         'title' => 'menu link',
         'link' => ['uri' => 'http://www.example.com'],
         'menu_name' => 'tools',
@@ -129,8 +129,8 @@ protected function createContent() {
     }
 
     // Create a taxonomy term.
-    if ($entityTypeManager->hasDefinition('taxonomy_term')) {
-      $term = Term::create([
+    if ($entity_type_manager->hasDefinition('taxonomy_term')) {
+      $term = $entity_type_manager->getStorage('aggregator_item')->create([
         'name' => 'term',
         'vid' => 'term',
       ]);
@@ -138,9 +138,8 @@ protected function createContent() {
     }
 
     // Create a user.
-    if ($entityTypeManager->hasDefinition('user')) {
-      $user = User::create([
-        'uid' => 2,
+    if ($entity_type_manager->hasDefinition('user')) {
+      $user = $entity_type_manager->getStorage('aggregator_item')->create([
         'name' => 'user',
         'mail' => 'user@example.com',
       ]);
@@ -152,11 +151,11 @@ protected function createContent() {
    * Create several pieces of generic content.
    */
   protected function createContentPostUpgrade() {
-    $entityTypeManager = \Drupal::entityTypeManager();
+    $entity_type_manager = \Drupal::entityTypeManager();
 
     // Create a block content.
-    if ($entityTypeManager->hasDefinition('block_content')) {
-      $block = BlockContent::create([
+    if ($entity_type_manager->hasDefinition('block_content')) {
+      $block = $entity_type_manager->getStorage('aggregator_item')->create([
         'info' => 'Post upgrade block',
         'type' => 'block',
       ]);
@@ -164,8 +163,8 @@ protected function createContentPostUpgrade() {
     }
 
     // Create a node.
-    if ($entityTypeManager->hasDefinition('node')) {
-      $node = Node::create([
+    if ($entity_type_manager->hasDefinition('node')) {
+      $node = $entity_type_manager->getStorage('aggregator_item')->create([
         'type' => 'page',
         'title' => 'Post upgrade page',
       ]);
@@ -173,8 +172,8 @@ protected function createContentPostUpgrade() {
     }
 
     // Create a comment.
-    if ($entityTypeManager->hasDefinition('comment')) {
-      $comment = Comment::create([
+    if ($entity_type_manager->hasDefinition('comment')) {
+      $comment = $entity_type_manager->getStorage('aggregator_item')->create([
         'comment_type' => 'comment',
         'field_name' => 'comment',
         'entity_type' => 'node',
@@ -183,16 +182,16 @@ protected function createContentPostUpgrade() {
       $comment->save();
     }
     // Create a file.
-    if ($entityTypeManager->hasDefinition('file')) {
-      $file = File::create([
+    if ($entity_type_manager->hasDefinition('file')) {
+      $file = $entity_type_manager->getStorage('file')->create([
         'uri' => 'public://post_upgrade_example.txt',
       ]);
       $file->save();
     }
 
     // Create a menu link.
-    if ($entityTypeManager->hasDefinition('menu_link_content')) {
-      $menu_link = MenuLinkContent::create([
+    if ($entity_type_manager->hasDefinition('menu_link_content')) {
+      $menu_link = $entity_type_manager->getStorage('menu_link_content')->create([
         'title' => 'post upgrade menu link',
         'link' => ['uri' => 'http://www.drupal.org'],
         'menu_name' => 'tools',
@@ -201,8 +200,8 @@ protected function createContentPostUpgrade() {
     }
 
     // Create a taxonomy term.
-    if ($entityTypeManager->hasDefinition('taxonomy_term')) {
-      $term = Term::create([
+    if ($entity_type_manager->hasDefinition('taxonomy_term')) {
+      $term = $entity_type_manager->getStorage('taxonomy_term')->create([
         'name' => 'post upgrade term',
         'vid' => 'term',
       ]);
@@ -210,9 +209,8 @@ protected function createContentPostUpgrade() {
     }
 
     // Create a user.
-    if ($entityTypeManager->hasDefinition('user')) {
-      $user = User::create([
-        'uid' => 42,
+    if ($entity_type_manager->hasDefinition('user')) {
+      $user = $entity_type_manager->getStorage('user')->create([
         'name' => 'universe',
         'mail' => 'universe@example.com',
       ]);