diff -u b/core/modules/comment/tests/src/Entity/CommentLockTest.php b/core/modules/comment/tests/src/Entity/CommentLockTest.php
--- b/core/modules/comment/tests/src/Entity/CommentLockTest.php
+++ b/core/modules/comment/tests/src/Entity/CommentLockTest.php
@@ -27,9 +27,9 @@
     $container->set('module_handler', $this->getMock('Drupal\Core\Extension\ModuleHandlerInterface'));
     $container->set('current_user', $this->getMock('Drupal\Core\Session\AccountInterface'));
     $container->set('cache.test', $this->getMock('Drupal\Core\Cache\CacheBackendInterface'));
-    $requestStack = new RequestStack();
-    $requestStack->push(Request::create('/'));
-    $container->set('request_stack', $requestStack);
+    $request_stack = new RequestStack();
+    $request_stack->push(Request::create('/'));
+    $container->set('request_stack', $request_stack);
     $container->setParameter('cache_bins', array('cache.test' => 'test'));
     $lock = $this->getMock('Drupal\Core\Lock\LockBackendInterface');
     $cid = 2;
diff -u b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
--- b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
+++ b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
@@ -16,7 +16,6 @@
 use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageInterface;
 use Symfony\Component\HttpFoundation\Request;
-use Symfony\Component\HttpFoundation\RequestStack;
 use Drupal\language\LanguageNegotiatorInterface;
 
 /**
@@ -63,11 +62,6 @@
   function setUp() {
     parent::setUp();
 
-    $this->request = Request::createFromGlobals();
-    $requestStack = new RequestStack();
-    $requestStack->push($this->request);
-    $this->container->set('request_stack', $requestStack);
-
     $admin_user = $this->drupalCreateUser(array('administer languages', 'translate interface', 'access administration pages', 'administer blocks'));
     $this->drupalLogin($admin_user);
   }
@@ -435,7 +429,7 @@
     // Base path gives problems on the testbot, so $correct_link is hard-coded.
     // @see UrlAlterFunctionalTest::assertUrlOutboundAlter (path.test).
     $italian_url = url('admin', array('language' => $languages['it'], 'script' => ''));
-    $url_scheme = $this->request->isSecure() ? 'https://' : 'http://';
+    $url_scheme = \Drupal::request()->isSecure() ? 'https://' : 'http://';
     $correct_link = $url_scheme . $link;
     $this->assertEqual($italian_url, $correct_link, format_string('The url() function returns the right URL (@url) in accordance with the chosen language', array('@url' => $italian_url)));
 
diff -u b/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
--- b/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -1089,9 +1089,9 @@
 
     $request = Request::create('/');
 
-    $requestStack = new RequestStack();
-    $requestStack->push($request);
-    $this->container->set('request_stack', $requestStack);
+    $request_stack = new RequestStack();
+    $request_stack->push($request);
+    $this->container->set('request_stack', $request_stack);
 
     // Run all tests as a anonymous user by default, web tests will replace that
     // during the test set up.