diff --git a/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonAnonTest.php b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonAnonTest.php
new file mode 100644
index 0000000..543ac6c
--- /dev/null
+++ b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonAnonTest.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Drupal\Tests\rest\Functional\EntityResource\Item;
+
+use Drupal\Tests\rest\Functional\AnonResourceTestTrait;
+
+/**
+ * @group rest
+ */
+class ItemJsonAnonTest extends ItemResourceTestBase {
+
+  use AnonResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+}
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonBasicAuthTest.php b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonBasicAuthTest.php
new file mode 100644
index 0000000..2d97826
--- /dev/null
+++ b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonBasicAuthTest.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Drupal\Tests\rest\Functional\EntityResource\Item;
+
+use Drupal\Tests\rest\Functional\BasicAuthResourceTestTrait;
+
+/**
+ * @group rest
+ */
+class ItemJsonBasicAuthTest extends ItemResourceTestBase {
+
+  use BasicAuthResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['basic_auth'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'basic_auth';
+}
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonCookieTest.php b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonCookieTest.php
new file mode 100644
index 0000000..1c149d7
--- /dev/null
+++ b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemJsonCookieTest.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace Drupal\Tests\rest\Functional\EntityResource\Item;
+
+use Drupal\Tests\rest\Functional\CookieResourceTestTrait;
+
+/**
+ * @group rest
+ */
+class ItemJsonCookieTest extends ItemResourceTestBase {
+
+  use CookieResourceTestTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $format = 'json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $mimeType = 'application/json';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $auth = 'cookie';
+
+}
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemResourceTestBase.php
new file mode 100644
index 0000000..efb913d
--- /dev/null
+++ b/core/modules/rest/tests/src/Functional/EntityResource/Item/ItemResourceTestBase.php
@@ -0,0 +1,182 @@
+<?php
+
+namespace Drupal\Tests\rest\Functional\EntityResource\Item;
+
+use Drupal\aggregator\Entity\Feed;
+use Drupal\aggregator\Entity\Item;
+use Drupal\aggregator\FeedInterface;
+use Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase;
+
+abstract class ItemResourceTestBase extends EntityResourceTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['aggregator'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $entityTypeId = 'aggregator_item';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $patchProtectedFieldNames = [
+    'timestamp',
+  ];
+
+  /**
+   * @var \Drupal\aggregator\ItemInterface.
+   */
+  protected $entity;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUpAuthorization($method) {
+    switch ($method) {
+      case 'GET':
+        $this->grantPermissionsToTestedRole(['access news feeds']);
+        break;
+      case 'POST':
+      case 'PATCH':
+      case 'DELETE':
+        $this->grantPermissionsToTestedRole(['administer news feeds']);
+        break;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createEntity() {
+    // Create a "Camelids" feed.
+    $feed = Feed::create(array(
+      'title' => 'Camelids',
+      'url' => 'https://groups.drupal.org/not_used/167169',
+      'refresh' => 900,
+      'checked' => 1389919932,
+      'description' => 'Drupal Core Group feed',
+    ));
+    $feed->save();
+
+    // Create a "Llama" item.
+    $item = Item::create([
+      'fid' => $feed->id(),
+      'title' => t('Llama'),
+      'link' => 'https://www.drupal.org/',
+    ]);
+    $item->setPostedTime(123456789)
+      ->save();
+
+    return $item;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedNormalizedEntity() {
+    /** @var FeedInterface $feed */
+    $feed = Feed::load($this->entity->getFeedId());
+    return [
+      'iid' => [
+        [
+          'value' => 1,
+        ],
+      ],
+      'langcode' => [
+        [
+          'value' => 'en',
+        ],
+      ],
+      'fid' => [
+        [
+          'target_id' => $feed->id(),
+          'target_type' => 'aggregator_feed',
+          'target_uuid' => $feed->uuid(),
+          'url' => $feed->toUrl()->toString(),
+        ],
+      ],
+      'title' => [
+        [
+          'value' => 'Llama',
+        ],
+      ],
+      'link' => [
+        [
+          'value' => 'https://www.drupal.org/',
+        ]
+      ],
+      'author' => [],
+      'description' => [],
+      'timestamp' => [
+        [
+          'value' => 123456789,
+        ],
+      ],
+      'guid' => [],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getNormalizedPostEntity() {
+    return [
+      'fid' => [
+        ['value' => Feed::load(1)->id()],
+      ],
+      'title' => [
+        ['value' => 'Llama'],
+      ],
+      'link' => [
+        ['value' => 'https://www.drupal.org/']
+      ],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedCacheContexts() {
+    // @see ::createEntity()
+    return ['user.permissions'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getExpectedUnauthorizedAccessMessage($method) {
+    if ($this->config('rest.settings')->get('bc_entity_resource_permissions')) {
+      return parent::getExpectedUnauthorizedAccessMessage($method);
+    }
+
+    switch ($method) {
+      case 'GET':
+        return "The 'access news feeds' permission is required.";
+      case 'POST':
+        return "The 'administer news feeds' permission is required.";
+      case 'PATCH':
+        return "The 'administer news feeds' permission is required.";
+      case 'DELETE':
+        return "The 'administer news feeds' permission is required.";
+      default:
+        return parent::getExpectedUnauthorizedAccessMessage($method);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function testPatch() {
+    $this->markTestSkipped();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function testDelete() {
+    $this->markTestSkipped();
+  }
+}