diff --git a/core/lib/Drupal/Core/Entity/EntityDatabaseStorage.php b/core/lib/Drupal/Core/Entity/EntityDatabaseStorage.php
deleted file mode 100644
index b55736d..0000000
--- a/core/lib/Drupal/Core/Entity/EntityDatabaseStorage.php
+++ /dev/null
@@ -1,212 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Entity\EntityDatabaseStorage.
- */
-
-namespace Drupal\Core\Entity;
-
-use Drupal\Component\Uuid\UuidInterface;
-use Drupal\Core\Database\Connection;
-use Symfony\Component\DependencyInjection\ContainerInterface;
-
-/**
- * Defines a base entity storage class.
- *
- * This class only supports bare, non-content entities.
- */
-class EntityDatabaseStorage extends EntityStorageBase {
-
-  /**
-   * The UUID service.
-   *
-   * @var \Drupal\Component\Uuid\UuidInterface
-   */
-  protected $uuidService;
-
-  /**
-   * Whether this entity type should use the static cache.
-   *
-   * @var boolean
-   */
-  protected $cache;
-
-  /**
-   * Active database connection.
-   *
-   * @var \Drupal\Core\Database\Connection
-   */
-  protected $database;
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function createInstance(ContainerInterface $container, EntityTypeInterface $entity_type) {
-    return new static(
-      $entity_type,
-      $container->get('database'),
-      $container->get('uuid')
-    );
-  }
-
-  /**
-   * Constructs a EntityDatabaseStorage object.
-   *
-   * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
-   *   The entity type definition.
-   * @param \Drupal\Core\Database\Connection $database
-   *   The database connection to be used.
-   * @param \Drupal\Component\Uuid\UuidInterface $uuid_service
-   *   The UUID service.
-   */
-  public function __construct(EntityTypeInterface $entity_type, Connection $database, UuidInterface $uuid_service) {
-    parent::__construct($entity_type);
-
-    $this->database = $database;
-    $this->uuidService = $uuid_service;
-
-    // Check if the entity type supports UUIDs.
-    $this->uuidKey = $this->entityType->getKey('uuid');
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function doLoadMultiple(array $ids = NULL) {
-    // Build and execute the query.
-    $records = $this
-      ->buildQuery($ids)
-      ->execute()
-      ->fetchAllAssoc($this->idKey, \PDO::FETCH_ASSOC);
-
-    return $this->mapFromStorageRecords($records);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function loadRevision($revision_id) {
-    throw new \Exception('Database storage does not support revisions.');
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function deleteRevision($revision_id) {
-    throw new \Exception('Database storage does not support revisions.');
-  }
-
-  /**
-   * Builds the query to load the entity.
-   *
-   * @param array|null $ids
-   *   An array of entity IDs, or NULL to load all entities.
-   *
-   * @return \Drupal\Core\Database\Query\Select
-   *   A SelectQuery object for loading the entity.
-   */
-  protected function buildQuery($ids) {
-    $query = $this->database->select($this->entityType->getBaseTable(), 'base');
-
-    $query->addTag($this->entityTypeId . '_load_multiple');
-
-    // Add fields from the {entity} table.
-    $entity_fields = drupal_schema_fields_sql($this->entityType->getBaseTable());
-    $query->fields('base', $entity_fields);
-
-    if ($ids) {
-      $query->condition("base.{$this->idKey}", $ids, 'IN');
-    }
-
-    return $query;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function delete(array $entities) {
-    if (!$entities) {
-      // If no IDs or invalid IDs were passed, do nothing.
-      return;
-    }
-    $transaction = $this->database->startTransaction();
-
-    try {
-      parent::delete($entities);
-
-      // Ignore replica server temporarily.
-      db_ignore_replica();
-    }
-    catch (\Exception $e) {
-      $transaction->rollback();
-      watchdog_exception($this->entityTypeId, $e);
-      throw new EntityStorageException($e->getMessage(), $e->getCode(), $e);
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function doDelete($entities) {
-    $ids = array_keys($entities);
-
-    $this->database->delete($this->entityType->getBaseTable())
-      ->condition($this->idKey, $ids, 'IN')
-      ->execute();
-
-    // Reset the cache as soon as the changes have been applied.
-    $this->resetCache($ids);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function save(EntityInterface $entity) {
-    $transaction = $this->database->startTransaction();
-    try {
-      $return = parent::save($entity);
-
-      // Ignore replica server temporarily.
-      db_ignore_replica();
-      return $return;
-    }
-    catch (\Exception $e) {
-      $transaction->rollback();
-      watchdog_exception($this->entityTypeId, $e);
-      throw new EntityStorageException($e->getMessage(), $e->getCode(), $e);
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function doSave($id, EntityInterface $entity) {
-    if (!$entity->isNew()) {
-      $return = drupal_write_record($this->entityType->getBaseTable(), $entity, $this->idKey);
-      $this->resetCache(array($entity->id()));
-    }
-    else {
-      $return = drupal_write_record($this->entityType->getBaseTable(), $entity);
-      // Reset general caches, but keep caches specific to certain entities.
-      $this->resetCache(array());
-    }
-
-    return $return;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function has($id, EntityInterface $entity) {
-    return !$entity->isNew();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getQueryServiceName() {
-    return 'entity.query.sql';
-  }
-
-}
diff --git a/core/modules/field_ui/tests/modules/field_ui_test/field_ui_test.info.yml b/core/modules/field_ui/tests/modules/field_ui_test/field_ui_test.info.yml
index b57d967..9d7a5d1 100644
--- a/core/modules/field_ui/tests/modules/field_ui_test/field_ui_test.info.yml
+++ b/core/modules/field_ui/tests/modules/field_ui_test/field_ui_test.info.yml
@@ -7,3 +7,4 @@ core: 8.x
 
 dependencies:
   - field_ui
+  - entity_test
diff --git a/core/modules/field_ui/tests/modules/field_ui_test/src/Entity/FieldUITestNoBundle.php b/core/modules/field_ui/tests/modules/field_ui_test/src/Entity/FieldUITestNoBundle.php
index be18202..e7b2113 100644
--- a/core/modules/field_ui/tests/modules/field_ui_test/src/Entity/FieldUITestNoBundle.php
+++ b/core/modules/field_ui/tests/modules/field_ui_test/src/Entity/FieldUITestNoBundle.php
@@ -7,27 +7,21 @@
 
 namespace Drupal\field_ui_test\Entity;
 
-use Drupal\Core\Entity\Entity;
+use Drupal\entity_test\Entity\EntityTest;
 
 /**
  * Defines the test Field UI class.
  *
- * @EntityType(
+ * @ContentEntityType(
  *   id = "field_ui_test_no_bundle",
  *   label = @Translation("Test Field UI entity, no bundle"),
- *   handlers = {
- *     "storage" = "Drupal\Core\Entity\EntityDatabaseStorage"
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "uuid" = "uuid",
  *   },
  *   fieldable = TRUE
  * )
  */
-class FieldUITestNoBundle extends Entity {
-
-  /**
-   * The entity ID.
-   *
-   * @var int
-   */
-  public $id;
+class FieldUITestNoBundle extends EntityTest {
 
 }
diff --git a/core/modules/system/src/Tests/Entity/EntityApiInfoTest.php b/core/modules/system/src/Tests/Entity/EntityApiInfoTest.php
deleted file mode 100644
index 8b48f95..0000000
--- a/core/modules/system/src/Tests/Entity/EntityApiInfoTest.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-
-/**
- * @file
- * Definition of Drupal\system\Tests\Entity\EntityApiInfoTest.
- */
-
-namespace Drupal\system\Tests\Entity;
-
-use Drupal\simpletest\WebTestBase;
-
-/**
- * Makes sure entity info is accurately cached.
- *
- * @group Entity
- */
-class EntityApiInfoTest extends WebTestBase  {
-
-  /**
-   * Ensures entity info cache is updated after changes.
-   */
-  function testEntityInfoChanges() {
-    \Drupal::moduleHandler()->install(array('entity_cache_test'));
-    $entity_types = \Drupal::entityManager()->getDefinitions();
-    $this->assertTrue(isset($entity_types['entity_cache_test']), 'Test entity type found.');
-
-    // Change the label of the test entity type and make sure changes appear
-    // after flushing caches.
-    \Drupal::state()->set('entity_cache_test.label', 'New label.');
-    $entity_type = \Drupal::entityManager()->getDefinition('entity_cache_test');
-    $this->assertEqual($entity_type->getLabel(), 'Entity Cache Test', 'Original label appears in cached entity info.');
-    $this->resetAll();
-    $entity_type = \Drupal::entityManager()->getDefinition('entity_cache_test');
-    $this->assertEqual($entity_type->getLabel(), 'New label.', 'New label appears in entity info.');
-
-    // Uninstall the providing module and make sure the entity type is gone.
-    $this->container->get('module_handler')->uninstall(array('entity_cache_test', 'entity_cache_test_dependency'));
-    $entity_types = \Drupal::entityManager()->getDefinitions();
-    $this->assertFalse(isset($entity_types['entity_cache_test']), 'Entity type of the providing module is gone.');
-  }
-
-  /**
-   * Tests entity info cache after enabling a module with a dependency on an entity providing module.
-   *
-   * @see entity_cache_test_modules_enabled()
-   */
-  function testEntityInfoCacheModulesEnabled() {
-    \Drupal::moduleHandler()->install(array('entity_cache_test'));
-    $entity_type = \Drupal::state()->get('entity_cache_test');
-    $this->assertEqual($entity_type->getLabel(), 'Entity Cache Test', 'Entity info label is correct.');
-    $this->assertEqual($entity_type->getStorageClass(), 'Drupal\Core\Entity\EntityDatabaseStorage', 'Entity handler class info is correct.');
-  }
-}
diff --git a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.info.yml b/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.info.yml
deleted file mode 100644
index fa4c0fe..0000000
--- a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.info.yml
+++ /dev/null
@@ -1,8 +0,0 @@
-name: 'Entity cache test'
-type: module
-description: 'Support module for testing entity cache.'
-package: Testing
-version: VERSION
-core: 8.x
-dependencies:
-  - entity_cache_test_dependency
diff --git a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module b/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
deleted file mode 100644
index f91afde..0000000
--- a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-/**
- * @file
- * Helper module for entity cache tests.
- */
-
-/**
- * Implements hook_modules_installed().
- *
- * This hook is called during \Drupal\Core\Extension\ModuleHandler::install()
- * and since this hook implementation is invoked, we have to expect that this
- * module and dependent modules have been properly installed already. So we
- * expect to be able to retrieve the entity information that has been registered
- * by the required dependency module.
- *
- * @see EntityApiInfoTest::testEntityInfoCacheModulesEnabled()
- */
-function entity_cache_test_modules_installed($modules_enabled) {
-  $info = \Drupal::entityManager()->getDefinition('entity_cache_test');
-  // Store the information in a system variable to analyze it later in the
-  // test case.
-  \Drupal::state()->set('entity_cache_test', $info);
-}
diff --git a/core/modules/system/tests/modules/entity_cache_test_dependency/entity_cache_test_dependency.info.yml b/core/modules/system/tests/modules/entity_cache_test_dependency/entity_cache_test_dependency.info.yml
deleted file mode 100644
index 282fcb7..0000000
--- a/core/modules/system/tests/modules/entity_cache_test_dependency/entity_cache_test_dependency.info.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-name: 'Entity cache test dependency'
-type: module
-description: 'Support dependency module for testing entity cache.'
-package: Testing
-version: VERSION
-core: 8.x
diff --git a/core/modules/system/tests/modules/entity_cache_test_dependency/entity_cache_test_dependency.module b/core/modules/system/tests/modules/entity_cache_test_dependency/entity_cache_test_dependency.module
deleted file mode 100644
index 7af3467..0000000
--- a/core/modules/system/tests/modules/entity_cache_test_dependency/entity_cache_test_dependency.module
+++ /dev/null
@@ -1,14 +0,0 @@
-<?php
-
-/**
- * @file
- * Helper module for entity cache tests.
- */
-
-/**
- * Implements hook_entity_type_alter().
- */
-function entity_cache_test_dependency_entity_type_alter(array &$entity_types) {
-  /** @var $entity_types \Drupal\Core\Entity\EntityTypeInterface[] */
-  $entity_types['entity_cache_test']->set('label', \Drupal::state()->get('entity_cache_test.label') ?: 'Entity Cache Test');
-}
diff --git a/core/modules/system/tests/modules/entity_cache_test_dependency/src/Entity/EntityCacheTest.php b/core/modules/system/tests/modules/entity_cache_test_dependency/src/Entity/EntityCacheTest.php
deleted file mode 100644
index 4c9c243..0000000
--- a/core/modules/system/tests/modules/entity_cache_test_dependency/src/Entity/EntityCacheTest.php
+++ /dev/null
@@ -1,25 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains Drupal\entity_cache_test_dependency\Entity\EntityCacheTest.
- */
-
-namespace Drupal\entity_cache_test_dependency\Entity;
-
-use Drupal\Core\Entity\Entity;
-
-/**
- * Defines the EntityCacheTest class.
- *
- * @EntityType(
- *   id = "entity_cache_test",
- *   label = @Translation("Entity cache test"),
- *   handlers = {
- *     "storage" = "Drupal\Core\Entity\EntityDatabaseStorage",
- *   }
- * )
- */
-class EntityCacheTest extends Entity {
-
-}