diff --git a/core/lib/Drupal/Core/Template/TwigEnvironment.php b/core/lib/Drupal/Core/Template/TwigEnvironment.php
index 886f555..24c9084 100644
--- a/core/lib/Drupal/Core/Template/TwigEnvironment.php
+++ b/core/lib/Drupal/Core/Template/TwigEnvironment.php
@@ -38,7 +38,7 @@ public function __construct(\Twig_LoaderInterface $loader = NULL, $options = arr
     // @todo Pass as arguments from the DIC.
     $this->cache_object = cache();
 
-    // Set twig path namespace for themes and modules
+    // Set twig path namespace for themes and modules.
     $namespaces = $module_handler->getModuleList();
     foreach ($theme_handler->listInfo() as $theme => $info) {
       $namespaces[$theme] = $info->filename;
diff --git a/core/modules/system/lib/Drupal/system/Tests/Theme/TwigNamespaceTest.php b/core/modules/system/lib/Drupal/system/Tests/Theme/TwigNamespaceTest.php
index 1068a3f..2d5ea69 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Theme/TwigNamespaceTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/TwigNamespaceTest.php
@@ -41,23 +41,30 @@ function setUp() {
   }
 
   /**
-   * Check to see if a value is a twig template.
+   * Checks to see if a value is a twig template.
    */
   public function assertTwigTemplate($value, $message = '', $group = 'Other') {
     $this->assertTrue($value instanceof \Twig_Template, $message, $group);
   }
 
+  /**
+   * Tests template discovery using namespaces.
+   */
   public function testTemplateDiscovery() {
-    // Enabled module
-    $this->assertTwigTemplate($this->twig->resolveTemplate('@node/node.html.twig'), 'Found node.tpl.php in node module.');
+    // Tests resolving namespaced templates in modules.
+    $this->assertTwigTemplate($this->twig->resolveTemplate('@node/node.html.twig'), 'Found node.html.twig in node module.');
 
-    // Enabled theme
-    $this->assertTwigTemplate($this->twig->resolveTemplate('@bartik/page.html.twig'), 'Found page.html.twig in bartik theme.');
+    // Tests resolving namespaced templates in themes.
+    $this->assertTwigTemplate($this->twig->resolveTemplate('@bartik/page.html.twig'), 'Found page.html.twig in Bartik theme.');
   }
 
+  /**
+   * Tests template extension and includes using namespaces.
+   */
   public function testTwigNamespaces() {
     // Test twig @extends and @include in template files.
-    $this->drupalSetContent(theme('twig_namespace_test'));
+    $test = array('#theme' => 'twig_namespace_test');
+    $this->drupalSetContent(drupal_render($test));
 
     $this->assertText('This line is from twig_namespace_a/templates/test.html.twig');
     $this->assertText('This line is from twig_namespace_b/templates/test.html.twig');
diff --git a/core/modules/system/tests/modules/twig_theme_test/modules/twig_namespace_a/templates/test.html.twig b/core/modules/system/tests/modules/twig_theme_test/modules/twig_namespace_a/templates/test.html.twig
index ed52e5e..94e1fc9 100644
--- a/core/modules/system/tests/modules/twig_theme_test/modules/twig_namespace_a/templates/test.html.twig
+++ b/core/modules/system/tests/modules/twig_theme_test/modules/twig_namespace_a/templates/test.html.twig
@@ -1,5 +1,5 @@
 This line is from twig_namespace_a/templates/test.html.twig
 
-{% block content  %}
+{% block content %}
 This text is in a block.
 {% endblock %}
diff --git a/core/modules/system/tests/modules/twig_theme_test/templates/twig_namespace_test.html.twig b/core/modules/system/tests/modules/twig_theme_test/templates/twig_namespace_test.html.twig
index ea9a806..5ac6e38 100644
--- a/core/modules/system/tests/modules/twig_theme_test/templates/twig_namespace_test.html.twig
+++ b/core/modules/system/tests/modules/twig_theme_test/templates/twig_namespace_test.html.twig
@@ -1,5 +1,5 @@
 {% extends "@twig_namespace_a/test.html.twig" %}
 
-{% block content  %}
+{% block content %}
   {% include "@twig_namespace_b/test.html.twig" %}
 {% endblock %}