diff -u b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php
--- b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php
@@ -48,7 +48,7 @@
     parent::setUp();
     $this->installEntitySchema($this->entityTypeId);
     $this->installConfig('language');
-    $this->entityStorage = $this->entityManager->getStorage($this->entityTypeId);
+    $this->entityStorage = $this->entityTypeManager->getStorage($this->entityTypeId);
 
     // Create the test entity reference field.
     FieldStorageConfig::create([
@@ -177,7 +177,6 @@
     $this->assertEquals(1, substr_count($serialized_main_entity, 'entity zero'));
     $this->assertEquals(1, substr_count($serialized_main_entity, 'entity one'));
 
-
     // Case 2: existing_entity_a->existing_entity_b->existing_entity_a_cloned
     /** @var \Drupal\entity_test\Entity\EntityTestMul $entity_level_zero */
     $entity_level_zero = $this->entityStorage->create([
@@ -210,7 +209,6 @@
     $this->assertEquals(2, substr_count($serialized_main_entity, 'entity zero'));
     $this->assertEquals(1, substr_count($serialized_main_entity, 'entity one'));
 
-
     // Case 3: existing_entity_a->existing_entity_b->existing_entity_a
     // Reset the entities for the next test.
     $entity_level_zero = $this->entityStorage->loadUnchanged($entity_level_zero->id());
@@ -232,7 +230,6 @@
     $this->assertEquals(2, substr_count($serialized_main_entity, 'entity zero'));
     $this->assertEquals(2, substr_count($serialized_main_entity, 'entity one'));
 
-
     // Case 4 : Like the previous case, but now show that no matter how deep a
     // nested structure with circular references is initialized the serialized
     // string will remain the same and will contain the serialized values to the