.../EntityTest/EntityTestMapItemNormalizerTest.php | 99 ++++++++++++++++------
 .../entity_test/src/Entity/EntityTestMapField.php  | 37 ++++++++
 2 files changed, 110 insertions(+), 26 deletions(-)

diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestMapItemNormalizerTest.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestMapItemNormalizerTest.php
index 754f7e1..f7386da 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestMapItemNormalizerTest.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityTest/EntityTestMapItemNormalizerTest.php
@@ -2,9 +2,9 @@
 
 namespace Drupal\Tests\rest\Functional\EntityResource\EntityTest;
 
-use Drupal\field\Entity\FieldConfig;
-use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\entity_test\Entity\EntityTestMapField;
 use Drupal\Tests\rest\Functional\AnonResourceTestTrait;
+use Drupal\user\Entity\User;
 
 /**
  * Test that MapItem are correctly exposed in REST.
@@ -20,6 +20,11 @@ class EntityTestMapItemNormalizerTest extends EntityTestResourceTestBase {
    */
   protected static $format = 'json';
 
+  /**
+   * {@inheritdoc}
+   */
+  protected static $entityTypeId = 'entity_test_map_field';
+
   protected static $mapValue = [
     'key1' => 'value',
     'key2' => 'no, val you',
@@ -37,36 +42,55 @@ class EntityTestMapItemNormalizerTest extends EntityTestResourceTestBase {
   /**
    * {@inheritdoc}
    */
+  protected function setUpAuthorization($method) {
+    $this->grantPermissionsToTestedRole(['administer entity_test content']);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   protected function getExpectedNormalizedEntity() {
-    $expected = parent::getExpectedNormalizedEntity();
-    $expected['field_map'] = [
-      0 => static::$mapValue
+    $author = User::load(0);
+    return [
+      'id' => [
+        [
+          'value' => 1,
+        ],
+      ],
+      'name' => [
+        [
+          'value' => 'Llama',
+        ],
+      ],
+      'created' => [
+        $this->formatExpectedTimestampItemValues((int) $this->entity->get('created')->value),
+      ],
+      'user_id' => [
+        [
+          'target_id' => (int) $author->id(),
+          'target_type' => 'user',
+          'target_uuid' => $author->uuid(),
+          'url' => $author->toUrl()->toString(),
+        ],
+      ],
+      'data' => [
+        0 => static::$mapValue,
+      ],
     ];
-    return $expected;
   }
 
   /**
    * {@inheritdoc}
    */
   protected function createEntity() {
-    if (!FieldStorageConfig::loadByName('entity_test', 'field_map')) {
-      FieldStorageConfig::create([
-        'entity_type' => 'entity_test',
-        'field_name' => 'field_map',
-        'type' => 'map',
-        'cardinality' => 1,
-        'translatable' => FALSE,
-      ])->save();
-      FieldConfig::create([
-        'entity_type' => 'entity_test',
-        'field_name' => 'field_map',
-        'bundle' => 'entity_test',
-        'label' => 'Test field with map property',
-      ])->save();
-    }
-
-    $entity = parent::createEntity();
-    $entity->get('field_map')->set(0, static::$mapValue);
+    $entity = EntityTestMapField::create([
+      'name' => 'Llama',
+      'type' => 'entity_test_map_field',
+      'data' => [
+        0 => static::$mapValue,
+      ]
+    ]);
+    $entity->setOwnerId(0);
     $entity->save();
     return $entity;
   }
@@ -75,11 +99,34 @@ protected function createEntity() {
    * {@inheritdoc}
    */
   protected function getNormalizedPostEntity() {
-    return parent::getNormalizedPostEntity() + [
-      'field_map' => [
+    return [
+      'name' => [
+        [
+          'value' => 'Dramallama',
+        ],
+      ],
+      'data' => [
         0 => static::$mapValue,
       ],
     ];
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedUnauthorizedAccessMessage($method) {
+    if ($this->config('rest.settings')->get('bc_entity_resource_permissions')) {
+      return parent::getExpectedUnauthorizedAccessMessage($method);
+    }
+
+    return "The 'administer entity_test content' permission is required.";
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedCacheContexts() {
+    return ['user.permissions'];
+  }
+
 }
diff --git a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestMapField.php b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestMapField.php
new file mode 100644
index 0000000..82bba32
--- /dev/null
+++ b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestMapField.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace Drupal\entity_test\Entity;
+
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
+
+/**
+ * An entity used for testing map base field values.
+ *
+ * @ContentEntityType(
+ *   id = "entity_test_map_field",
+ *   label = @Translation("Entity Test map field"),
+ *   base_table = "entity_test_map_field",
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "label" = "name",
+ *   },
+ *   admin_permission = "administer entity_test content",
+ * )
+ */
+class EntityTestMapField extends EntityTest {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
+    $fields = parent::baseFieldDefinitions($entity_type);
+
+    $fields['data'] = BaseFieldDefinition::create('map')
+      ->setLabel(t('Data'))
+      ->setDescription(t('A serialized array of additional data.'));
+
+    return $fields;
+  }
+
+}