diff --git a/core/tests/Drupal/Tests/Core/DependencyInjection/ContainerBuilderTest.php b/core/tests/Drupal/Tests/Core/DependencyInjection/ContainerBuilderTest.php
index 8ee93ee..4e2e855 100644
--- a/core/tests/Drupal/Tests/Core/DependencyInjection/ContainerBuilderTest.php
+++ b/core/tests/Drupal/Tests/Core/DependencyInjection/ContainerBuilderTest.php
@@ -9,10 +9,10 @@
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Tests\UnitTestCase;
+use Drupal\Tests\Core\DependencyInjection\Fixture\BazClass;
+use Drupal\Tests\Core\DependencyInjection\Fixture\BarClass;
 use Symfony\Component\DependencyInjection\Reference;
-use Symfony\Component\Routing\Tests\Fixtures\AnnotatedClasses\BarClass;
-
-require_once __DIR__ . '/classes.php';
+use Symfony\Component\Routing\Tests\Fixtures\AnnotatedClasses\BarClass as AnnotatedBarClass;
 
 /**
  * @coversDefaultClass \Drupal\Core\DependencyInjection\ContainerBuilder
@@ -25,18 +25,18 @@ class ContainerBuilderTest extends UnitTestCase {
    */
   public function testSetOnSynchronizedService() {
     $container = new ContainerBuilder();
-    $container->register('baz', 'BazClass')
+    $container->register('baz', '\Drupal\Tests\Core\DependencyInjection\Fixture\BazClass')
       ->setSynchronized(TRUE);
-    $container->register('bar', 'BarClass')
+    $container->register('bar', '\Drupal\Tests\Core\DependencyInjection\Fixture\BarClass')
       ->addMethodCall('setBaz', array(new Reference('baz')));
 
     // Ensure that we can set services on a compiled container.
     $container->compile();
 
-    $container->set('baz', $baz = new \BazClass());
+    $container->set('baz', $baz = new BazClass());
     $this->assertSame($baz, $container->get('bar')->getBaz());
 
-    $container->set('baz', $baz = new \BazClass());
+    $container->set('baz', $baz = new BazClass());
     $this->assertSame($baz, $container->get('bar')->getBaz());
   }
 
@@ -47,10 +47,10 @@ public function testSetOnSynchronizedService() {
    */
   public function testGet() {
     $container = new ContainerBuilder();
-    $container->register('bar', 'BarClass');
+    $container->register('bar', 'Drupal\Tests\Core\DependencyInjection\Fixture\BarClass');
 
     $result = $container->get('bar');
-    $this->assertTrue($result instanceof \BarClass);
+    $this->assertTrue($result instanceof BarClass);
   }
 
   /**
@@ -60,7 +60,7 @@ public function testGet() {
    */
   public function testSet() {
     $container = new ContainerBuilder();
-    $class = new BarClass();
+    $class = new AnnotatedBarClass();
     $container->set('bar', $class);
     $this->assertEquals('bar', $class->_serviceId);
   }
diff --git a/core/tests/Drupal/Tests/Core/DependencyInjection/Fixture/BarClass.php b/core/tests/Drupal/Tests/Core/DependencyInjection/Fixture/BarClass.php
new file mode 100644
index 0000000..4c76795
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/DependencyInjection/Fixture/BarClass.php
@@ -0,0 +1,27 @@
+<?php
+
+/**
+ * @file
+ * A stub class for use with ContainerBuilderTest.
+ *
+ * @see Drupal\Tests\Core\DependencyInjection\ContainerBuilderTest
+ */
+
+namespace Drupal\Tests\Core\DependencyInjection\Fixture;
+
+class BarClass
+{
+    protected $baz;
+
+    public $foo = 'foo';
+
+    public function setBaz(BazClass $baz)
+    {
+        $this->baz = $baz;
+    }
+
+    public function getBaz()
+    {
+        return $this->baz;
+    }
+}
diff --git a/core/tests/Drupal/Tests/Core/DependencyInjection/Fixture/BazClass.php b/core/tests/Drupal/Tests/Core/DependencyInjection/Fixture/BazClass.php
new file mode 100644
index 0000000..1087a7e
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/DependencyInjection/Fixture/BazClass.php
@@ -0,0 +1,36 @@
+<?php
+
+/**
+ * @file
+ * A stub class for use with ContainerBuilderTest.
+ *
+ * @see Drupal\Tests\Core\DependencyInjection\ContainerBuilderTest
+ */
+
+namespace Drupal\Tests\Core\DependencyInjection\Fixture;
+
+class BazClass {
+
+  protected $foo;
+
+  public function setFoo(Foo $foo) {
+    $this->foo = $foo;
+  }
+
+  public function configure($instance) {
+    $instance->configure();
+  }
+
+  public static function getInstance() {
+    return new self();
+  }
+
+  public static function configureStatic($instance) {
+    $instance->configure();
+  }
+
+  public static function configureStatic1() {
+
+  }
+
+}
diff --git a/core/tests/Drupal/Tests/Core/DependencyInjection/classes.php b/core/tests/Drupal/Tests/Core/DependencyInjection/classes.php
deleted file mode 100644
index eed11a4..0000000
--- a/core/tests/Drupal/Tests/Core/DependencyInjection/classes.php
+++ /dev/null
@@ -1,71 +0,0 @@
-<?php
-
-/**
- * @file
- * Stub classes used for testing by ContainerBuilderTest.
- *
- * Note that this file is a verbatim copy of
- * Symfony/Component/DependencyInjection/Tests/Fixtures/includes/classes.php.
- *
- * @see Drupal\Tests\Core\DependencyInjection\ContainerBuilderTest
- */
-
-function sc_configure($instance)
-{
-    $instance->configure();
-}
-
-class BarClass
-{
-    protected $baz;
-    public $foo = 'foo';
-
-    public function setBaz(BazClass $baz)
-    {
-        $this->baz = $baz;
-    }
-
-    public function getBaz()
-    {
-        return $this->baz;
-    }
-}
-
-class BazClass
-{
-    protected $foo;
-
-    public function setFoo(Foo $foo)
-    {
-        $this->foo = $foo;
-    }
-
-    public function configure($instance)
-    {
-        $instance->configure();
-    }
-
-    public static function getInstance()
-    {
-        return new self();
-    }
-
-    public static function configureStatic($instance)
-    {
-        $instance->configure();
-    }
-
-    public static function configureStatic1()
-    {
-    }
-}
-
-class BarUserClass
-{
-    public $bar;
-
-    public function __construct(BarClass $bar)
-    {
-        $this->bar = $bar;
-    }
-}