diff --git a/core/modules/config/src/Tests/AssertConfigEntityImportTrait.php b/core/modules/config/src/Tests/AssertConfigEntityImportTrait.php
index 044144483a..c150e7ed2b 100644
--- a/core/modules/config/src/Tests/AssertConfigEntityImportTrait.php
+++ b/core/modules/config/src/Tests/AssertConfigEntityImportTrait.php
@@ -2,36 +2,16 @@
 
 namespace Drupal\config\Tests;
 
-use Drupal\Core\Config\Entity\ConfigEntityInterface;
+@trigger_error('The ' . __NAMESPACE__ . '\AssertConfigEntityImportTrait is deprecated in Drupal 8.4.x and will be removed before Drupal 9.0.0. Instead, use \Drupal\Tests\config\Traits\AssertConfigEntityImportTrait', E_USER_DEPRECATED);
 
 /**
  * Provides test assertions for testing config entity synchronization.
  *
- * Can be used by test classes that extend \Drupal\simpletest\WebTestBase or
- * \Drupal\KernelTests\KernelTestBase.
+ * @deprecated in Drupal 8.4.x and will be removed before Drupal 9.0.0.
+ *   Use \Drupal\Tests\config\Traits\AssertConfigEntityImportTrait.
  */
 trait AssertConfigEntityImportTrait {
 
-  /**
-   * Asserts that a config entity can be imported without changing it.
-   *
-   * @param \Drupal\Core\Config\Entity\ConfigEntityInterface $entity
-   *   The config entity to test importing.
-   */
-  public function assertConfigEntityImport(ConfigEntityInterface $entity) {
-    // Save original config information.
-    $entity_uuid = $entity->uuid();
-    $entity_type_id = $entity->getEntityTypeId();
-    $original_data = $entity->toArray();
-    // Copy everything to sync.
-    $this->copyConfig(\Drupal::service('config.storage'), \Drupal::service('config.storage.sync'));
-    // Delete the configuration from active. Don't worry about side effects of
-    // deleting config like fields cleaning up field storages. The coming import
-    // should recreate everything as necessary.
-    $entity->delete();
-    $this->configImporter()->reset()->import();
-    $imported_entity = \Drupal::entityManager()->loadEntityByUuid($entity_type_id, $entity_uuid);
-    $this->assertIdentical($original_data, $imported_entity->toArray());
-  }
+  use \Drupal\Tests\config\Traits\AssertConfigEntityImportTrait;
 
 }
diff --git a/core/modules/config/tests/src/Traits/AssertConfigEntityImportTrait.php b/core/modules/config/tests/src/Traits/AssertConfigEntityImportTrait.php
new file mode 100644
index 0000000000..e83bedc651
--- /dev/null
+++ b/core/modules/config/tests/src/Traits/AssertConfigEntityImportTrait.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace Drupal\Tests\config\Traits;
+
+use Drupal\Core\Config\Entity\ConfigEntityInterface;
+
+/**
+ * Provides test assertions for testing config entity synchronization.
+ *
+ * Can be used by test classes that extend \Drupal\simpletest\WebTestBase or
+ * \Drupal\KernelTests\KernelTestBase.
+ */
+trait AssertConfigEntityImportTrait {
+
+  /**
+   * Asserts that a config entity can be imported without changing it.
+   *
+   * @param \Drupal\Core\Config\Entity\ConfigEntityInterface $entity
+   *   The config entity to test importing.
+   */
+  public function assertConfigEntityImport(ConfigEntityInterface $entity) {
+    // Save original config information.
+    $entity_uuid = $entity->uuid();
+    $entity_type_id = $entity->getEntityTypeId();
+    $original_data = $entity->toArray();
+    // Copy everything to sync.
+    $this->copyConfig(\Drupal::service('config.storage'), \Drupal::service('config.storage.sync'));
+    // Delete the configuration from active. Don't worry about side effects of
+    // deleting config like fields cleaning up field storages. The coming import
+    // should recreate everything as necessary.
+    $entity->delete();
+    $this->configImporter()->reset()->import();
+    $imported_entity = \Drupal::entityManager()->loadEntityByUuid($entity_type_id, $entity_uuid);
+    $this->assertIdentical($original_data, $imported_entity->toArray());
+  }
+
+}
diff --git a/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php b/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php
index 56484705e1..ea65c4b931 100644
--- a/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php
+++ b/core/modules/field/tests/src/Functional/EntityReference/EntityReferenceIntegrationTest.php
@@ -3,11 +3,11 @@
 namespace Drupal\Tests\field\Functional\EntityReference;
 
 use Drupal\Component\Utility\SafeMarkup;
-use Drupal\config\Tests\AssertConfigEntityImportTrait;
 use Drupal\entity_test\Entity\EntityTest;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\Tests\BrowserTestBase;
 use Drupal\field\Tests\EntityReference\EntityReferenceTestTrait;
+use Drupal\Tests\config\Traits\AssertConfigEntityImportTrait;
 
 /**
  * Tests various Entity reference UI components.