diff --git a/core/lib/Drupal/Core/Theme/ThemeHandlerInterface.php b/core/lib/Drupal/Core/Theme/ThemeHandlerInterface.php
index fb7c850..02ce576 100644
--- a/core/lib/Drupal/Core/Theme/ThemeHandlerInterface.php
+++ b/core/lib/Drupal/Core/Theme/ThemeHandlerInterface.php
@@ -69,9 +69,9 @@ public function disable(array $theme_list);
    *   - sub_themes: An associative array of themes on the system that are
    *     either direct sub-themes (that is, they declare this theme to be
    *     their base theme), direct sub-themes of sub-themes, etc. The keys are
-   *     the themes' machine names, and the values are the themes' human-readable
-   *     names. This element is not set if there are no themes on the system that
-   *     declare this theme as their base theme.
+   *     the themes' machine names, and the values are the themes'
+   *     human-readable names. This element is not set if there are no themes on
+   *     the system that declare this theme as their base theme.
    */
   public function listInfo();
 
@@ -100,8 +100,8 @@ public function rebuildThemeData();
    *   The name of the theme whose base we are looking for.
    *
    * @return array
-   *   Returns an array of all of the theme's ancestors; the first element's value
-   *   will be NULL if an error occurred.
+   *   Returns an array of all of the theme's ancestors; the first element's
+   *   value will be NULL if an error occurred.
    */
   public function getBaseThemes(array $themes, $theme);
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/Batch/PageTest.php b/core/modules/system/lib/Drupal/system/Tests/Batch/PageTest.php
index fa26bfd..f268e02 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Batch/PageTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Batch/PageTest.php
@@ -50,7 +50,6 @@ function testBatchProgressPageTheme() {
     $this->drupalGet('admin/batch-test/test-theme');
     // The stack should contain the name of the theme used on the progress
     // page.
-    debug(batch_test_stack());
     $this->assertEqual(batch_test_stack(), array('seven'), 'A progressive batch correctly uses the theme of the page that started the batch.');
   }
 }
diff --git a/core/tests/Drupal/Tests/Core/Theme/ThemeHandlerTest.php b/core/tests/Drupal/Tests/Core/Theme/ThemeHandlerTest.php
index 2c20eaf..58b1594 100644
--- a/core/tests/Drupal/Tests/Core/Theme/ThemeHandlerTest.php
+++ b/core/tests/Drupal/Tests/Core/Theme/ThemeHandlerTest.php
@@ -275,11 +275,31 @@ public function testRebuildThemeData() {
   }
 
   /**
-   * Tests a theme without any base theme.
+   * Tests getting the base themes for a set a defines themes.
    *
-   * @covers \Drupal\Core\Theme\ThemeHandler::getBaseThemes()
+   * @param array $themes
+   *   An array of available themes, keyed by the theme name.
+   * @param string $theme
+   *   The theme name to find all its base themes.
+   * @param array $expected
+   *   The expected base themes.
+   *
+   * @dataProvider providerTestGetBaseThemes
+   */
+  public function testGetBaseThemes(array $themes, $theme, array $expected) {
+    $base_themes = $this->themeHandler->getBaseThemes($themes, $theme);
+    $this->assertEquals($expected, $base_themes);
+  }
+
+  /**
+   * Provides test data for testGetBaseThemes
+   *
+   * @return array
    */
-  public function testGetBaseThemesWithoutBaseTheme() {
+  public function providerTestGetBaseThemes() {
+    $data = array();
+
+    // Tests a theme without any base theme.
     $themes = array();
     $themes['test_1'] = (object) array(
       'name' => 'test_1',
@@ -287,16 +307,9 @@ public function testGetBaseThemesWithoutBaseTheme() {
         'name' => 'test_1',
       ),
     );
-    $base_themes = $this->themeHandler->getBaseThemes($themes, 'test_1');
-    $this->assertEquals(array(), $base_themes);
-  }
+    $data[] = array($themes, 'test_1', array());
 
-  /**
-   * Tests a theme with a non existing base theme.
-   *
-   * @covers \Drupal\Core\Theme\ThemeHandler::getBaseThemes()
-   */
-  public function testGetBaseThemesWithNonExistingBaseTheme() {
+    // Tests a theme with a non existing base theme.
     $themes = array();
     $themes['test_1'] = (object) array(
       'name' => 'test_1',
@@ -305,16 +318,9 @@ public function testGetBaseThemesWithNonExistingBaseTheme() {
         'base theme' => 'test_2',
       ),
     );
-    $base_themes = $this->themeHandler->getBaseThemes($themes, 'test_1');
-    $this->assertEquals(array('test_2' => NULL), $base_themes);
-  }
+    $data[] = array($themes, 'test_1', array('test_2' => NULL));
 
-  /**
-   * Tests a theme with a single existing base theme.
-   *
-   * @covers \Drupal\Core\Theme\ThemeHandler::getBaseThemes()
-   */
-  public function testGetBaseThemesWithOneBaseTheme() {
+    // Tests a theme with a single existing base theme.
     $themes = array();
     $themes['test_1'] = (object) array(
       'name' => 'test_1',
@@ -329,16 +335,9 @@ public function testGetBaseThemesWithOneBaseTheme() {
         'name' => 'test_2',
       ),
     );
-    $base_themes = $this->themeHandler->getBaseThemes($themes, 'test_1');
-    $this->assertEquals(array('test_2' => 'test_2'), $base_themes);
-  }
+    $data[] = array($themes, 'test_1', array('test_2' => 'test_2'));
 
-  /**
-   * Tests a theme with multiple base themes.
-   *
-   * @covers \Drupal\Core\Theme\ThemeHandler::getBaseThemes()
-   */
-  public function testGetBaseThemesWithMultipleBaseThemes() {
+    // Tests a theme with multiple base themes.
     $themes = array();
     $themes['test_1'] = (object) array(
       'name' => 'test_1',
@@ -360,8 +359,9 @@ public function testGetBaseThemesWithMultipleBaseThemes() {
         'name' => 'test_3',
       ),
     );
-    $base_themes = $this->themeHandler->getBaseThemes($themes, 'test_1');
-    $this->assertEquals(array('test_2' => 'test_2', 'test_3' => 'test_3'), $base_themes);
+    $data[] = array($themes, 'test_1', array('test_2' => 'test_2', 'test_3' => 'test_3'));
+
+    return $data;
   }
 
 }