Update to Drupal 8.0.0-rc3. For more information, see https://www.drupal.org/node/2608078

core/modules/aggregator/aggregator.install

@@ -21,3 +21,19 @@ function aggregator_requirements($phase) {
   }
   return $requirements;
 }
+
+/**
+ * @addtogroup updates-8.0.0-rc
+ * @{
+ */
+
+/**
+ * The simple presence of this update function clears cached field definitions.
+ */
+function aggregator_update_8001() {
+  // Feed ID base field is now required.
+}
+
+/**
+ * @} End of "addtogroup updates-8.0.0-rc".
+ */

core/modules/aggregator/src/Entity/Feed.php

@@ -53,7 +53,7 @@ use Drupal\aggregator\FeedInterface;
 class Feed extends ContentEntityBase implements FeedInterface {
 
   /**
-   * Implements Drupal\Core\Entity\EntityInterface::label().
+   * {@inheritdoc}
    */
   public function label() {
     return $this->get('title')->value;

core/modules/aggregator/src/Entity/Item.php

@@ -42,7 +42,7 @@ use Drupal\Core\Url;
 class Item extends ContentEntityBase implements ItemInterface {
 
   /**
-   * Implements Drupal\Core\Entity\EntityInterface::label().
+   * {@inheritdoc}
    */
   public function label() {
     return $this->get('title')->value;
@@ -60,6 +60,7 @@ class Item extends ContentEntityBase implements ItemInterface {
 
     $fields['fid'] = BaseFieldDefinition::create('entity_reference')
       ->setLabel(t('Source feed'))
+      ->setRequired(TRUE)
       ->setDescription(t('The aggregator feed entity associated with this item.'))
       ->setSetting('target_type', 'aggregator_feed')
       ->setDisplayOptions('view', array(

core/modules/aggregator/src/FeedHtmlRouteProvider.php

@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains Drupal\aggregator\FeedHtmlRouteProvider.
+ * Contains \Drupal\aggregator\FeedHtmlRouteProvider.
  */
 
 namespace Drupal\aggregator;

core/modules/aggregator/src/Plugin/views/row/Rss.php

@@ -50,7 +50,6 @@ class Rss extends RssPluginBase {
 
     $item = new \stdClass();
     foreach ($entity as $name => $field) {
-      // views_view_row_rss takes care about the escaping.
       $item->{$name} = $field->value;
     }
 

core/modules/aggregator/src/Tests/AggregatorTestBase.php

@@ -166,7 +166,7 @@ abstract class AggregatorTestBase extends WebTestBase {
   public function updateFeedItems(FeedInterface $feed, $expected_count = NULL) {
     // First, let's ensure we can get to the rss xml.
     $this->drupalGet($feed->getUrl());
-    $this->assertResponse(200, format_string('!url is reachable.', array('!url' => $feed->getUrl())));
+    $this->assertResponse(200, format_string(':url is reachable.', array(':url' => $feed->getUrl())));
 
     // Attempt to access the update link directly without an access token.
     $this->drupalGet('admin/config/services/aggregator/update/' . $feed->id());

core/modules/aggregator/src/Tests/ItemWithoutFeedTest.php

@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\aggregator\Tests\ItemWithoutFeedTest.
+ */
+
+namespace Drupal\aggregator\Tests;
+
+use Drupal\aggregator\Entity\Item;
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Tests clean handling of an item with a missing feed ID.
+ *
+ * @group aggregator
+ */
+class ItemWithoutFeedTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['aggregator', 'options'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->installEntitySchema('aggregator_feed');
+    $this->installEntitySchema('aggregator_item');
+  }
+
+  /**
+   * Tests attempting to create a feed item without a feed.
+   */
+  public function testEntityCreation() {
+    $entity = Item::create([
+      'title' => t('Llama 2'),
+      'path' => 'https://groups.drupal.org/',
+    ]);
+    $violations = $entity->validate();
+    $this->assertCount(1, $violations);
+  }
+
+}

core/modules/aggregator/tests/modules/aggregator_test/src/Plugin/aggregator/fetcher/TestFetcher.php

@@ -25,7 +25,7 @@ use Drupal\aggregator\FeedInterface;
 class TestFetcher extends DefaultFetcher implements FetcherInterface {
 
   /**
-   * Implements \Drupal\aggregator\Plugin\FetcherInterface::fetch().
+   * {@inheritdoc}
    */
   public function fetch(FeedInterface $feed) {
     if ($feed->label() == 'Do not fetch') {