Update to Drupal 8.0.0 beta 14. For more information, see https://drupal.org/node/2544542

core/modules/update/migration_templates/d6_update_settings.yml

@@ -0,0 +1,21 @@
+id: d6_update_settings
+label: Drupal 6 update configuration
+migration_tags:
+  - Drupal 6
+source:
+  plugin: variable
+  variables:
+    - update_max_fetch_attempts
+    - update_fetch_url
+    - update_notification_threshold
+    - update_notify_emails
+    - update_check_frequency
+process:
+  'fetch/max_attempts': update_max_fetch_attempts
+  'fetch/url': update_fetch_url
+  'notification/threshold': update_notification_threshold
+  'notification/emails': update_notify_emails
+  'check/interval_days': update_check_frequency
+destination:
+  plugin: config
+  config_name: update.settings

core/modules/update/src/Tests/Migrate/d6/MigrateUpdateConfigsTest.php

@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\update\Tests\Migrate\d6\MigrateUpdateConfigsTest.
+ */
+
+namespace Drupal\update\Tests\Migrate\d6;
+
+use Drupal\config\Tests\SchemaCheckTestTrait;
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
+
+/**
+ * Upgrade variables to update.settings.yml.
+ *
+ * @group update
+ */
+class MigrateUpdateConfigsTest extends MigrateDrupal6TestBase {
+
+  use SchemaCheckTestTrait;
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('update');
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->loadDumps(['Variable.php']);
+    $this->executeMigration('d6_update_settings');
+  }
+
+  /**
+   * Tests migration of update variables to update.settings.yml.
+   */
+  public function testUpdateSettings() {
+    $config = $this->config('update.settings');
+    $this->assertIdentical(2, $config->get('fetch.max_attempts'));
+    $this->assertIdentical('http://updates.drupal.org/release-history', $config->get('fetch.url'));
+    $this->assertIdentical('all', $config->get('notification.threshold'));
+    $this->assertIdentical(array(), $config->get('notification.emails'));
+    $this->assertIdentical(7, $config->get('check.interval_days'));
+    $this->assertConfigSchema(\Drupal::service('config.typed'), 'update.settings', $config->get());
+  }
+
+}

core/modules/update/tests/src/Unit/UpdateFetcherTest.php

@@ -33,9 +33,7 @@ class UpdateFetcherTest extends UnitTestCase {
    */
   protected function setUp() {
     $config_factory = $this->getConfigFactoryStub(array('update.settings' => array('fetch_url' => 'http://www.example.com')));
-    $http_client_mock = $this->getMockBuilder('Drupal\Core\Http\Client')
-      ->disableOriginalConstructor()
-      ->getMock();
+    $http_client_mock = $this->getMock('\GuzzleHttp\ClientInterface');
     $this->updateFetcher = new UpdateFetcher($config_factory, $http_client_mock);
   }