diff --git a/core/modules/system/lib/Drupal/system/PhpStorage/MockPhpStorage.php b/core/modules/system/lib/Drupal/system/PhpStorage/MockPhpStorage.php
index 0874148..0ef5e62 100644
--- a/core/modules/system/lib/Drupal/system/PhpStorage/MockPhpStorage.php
+++ b/core/modules/system/lib/Drupal/system/PhpStorage/MockPhpStorage.php
@@ -7,6 +7,39 @@
 
 namespace Drupal\system\PhpStorage;
 
+/**
+ * Mock PHP storage class used for testing.
+ */
 class MockPhpStorage {
 
+  /**
+   * The storage configuration.
+   *
+   * @var array
+   */
+  protected $configuration;
+
+  /**
+   * Constructs a MockPhpStorage object.
+   *
+   * @param array $configuration
+   */
+  public function __construct(array $configuration) {
+    $this->configuration = $configuration;
+  }
+
+  /**
+   * Gets the configuration data.
+   */
+  public function getConfiguration() {
+    return $this->configuration;
+  }
+
+  /**
+   * Gets a single configuration key.
+   */
+  public function getConfigurationValue($key) {
+    return isset($this->configuration[$key]) ? $this->configuration[$key] : NULL;
+  }
+
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/PhpStorage/PhpStorageFactoryTest.php b/core/modules/system/lib/Drupal/system/Tests/PhpStorage/PhpStorageFactoryTest.php
index f788a0f..5ff16d3 100644
--- a/core/modules/system/lib/Drupal/system/Tests/PhpStorage/PhpStorageFactoryTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/PhpStorage/PhpStorageFactoryTest.php
@@ -7,12 +7,12 @@
 
 namespace Drupal\system\Tests\PhpStorage;
 
-use Drupal\Component\PhpStorage\FileReadOnlyStorage;
 use Drupal\Component\PhpStorage\MTimeProtectedFileStorage;
-use Drupal\Component\PhpStorage\MTimeProtectedFastFileStorage;
 use Drupal\Component\Utility\Settings;
 use Drupal\Core\PhpStorage\PhpStorageFactory;
+use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\simpletest\DrupalUnitTestBase;
+use Drupal\system\PhpStorage\MockPhpStorage;
 
 /**
  * Tests the PHP storage factory.
@@ -42,32 +42,39 @@ public function testGetNoSettings() {
   }
 
   /**
+   * Tests the get() method using the 'default' settings.
+   */
+  public function testGetDefault() {
+    $this->setSettings();
+    $php = PhpStorageFactory::get('test');
+    $this->assertTrue($php instanceof MockPhpStorage, 'A FileReadOnlyStorage instance was returned with default settings.');
+  }
+
+  /**
    * Tests the get() method with overridden settings.
    */
   public function testGetOverride() {
     $this->setSettings('test');
     $php = PhpStorageFactory::get('test');
     // The FileReadOnlyStorage should be used from settings.
-    $this->assertTrue($php instanceof FileReadOnlyStorage, 'A FileReadOnlyStorage instance was returned from overridden settings.');
+    $this->assertTrue($php instanceof MockPhpStorage, 'A MockPhpStorage instance was returned from overridden settings.');
 
-    // Test with a protected storage class.
-    $this->setSettings('test', 'Drupal\Component\PhpStorage\MTimeProtectedFastFileStorage');
+    // Test that the name is used for the bin when it is NULL.
+    $this->setSettings('test', array('bin' => NULL));
     $php = PhpStorageFactory::get('test');
-    $this->assertTrue($php instanceof MTimeProtectedFastFileStorage, 'An MTimeProtectedFastFileStorage instance was returned from overridden settings.');
+    $this->assertTrue($php instanceof MockPhpStorage, 'An MockPhpStorage instance was returned from overridden settings.');
+    $this->assertIdentical('test', $php->getConfigurationValue('bin'), 'Name value was used for bin.');
 
-    // Test that the name is used for the bin when it is NULL.
-    $this->setSettings('test', 'Drupal\Component\PhpStorage\MTimeProtectedFastFileStorage', NULL);
+    // Test that a default directory is set if it's empty.
+    $this->setSettings('test', array('directory' => NULL));
     $php = PhpStorageFactory::get('test');
-    $this->assertTrue($php instanceof MTimeProtectedFastFileStorage, 'An MTimeProtectedFastFileStorage instance was returned from overridden settings.');
-  }
+    $this->assertTrue($php instanceof MockPhpStorage, 'An MockPhpStorage instance was returned from overridden settings.');
+    $this->assertIdentical(DRUPAL_ROOT . '/' . PublicStream::basePath() . '/php', $php->getConfigurationValue('directory'), 'Default file directory was used.');
 
-  /**
-   * Tests the get() method using the 'default' settings.
-   */
-  public function testGetDefault() {
-    $this->setSettings();
+    // Test that a default storage class is set if it's empty.
+    $this->setSettings('test', array('class' => NULL));
     $php = PhpStorageFactory::get('test');
-    $this->assertTrue($php instanceof FileReadOnlyStorage, 'A FileReadOnlyStorage instance was returned with default settings.');
+    $this->assertTrue($php instanceof MTimeProtectedFileStorage, 'An MTimeProtectedFileStorage instance was returned from overridden settings with no class.');
   }
 
   /**
@@ -75,12 +82,12 @@ public function testGetDefault() {
    *
    * @param string $name
    *   The storage bin name to set.
-   * @param string $class
-   *   The class that should be set for this bin.
+   * @param array $configuration
+   *   An array of configuration to set. Will be merged with default values.
    */
-  protected function setSettings($name = 'default', $class = 'Drupal\Component\PhpStorage\FileReadOnlyStorage') {
-    $settings['php_storage'][$name] = array(
-      'class' => $class,
+  protected function setSettings($name = 'default', array $configuration = array()) {
+    $settings['php_storage'][$name] = $configuration + array(
+      'class' => 'Drupal\system\PhpStorage\MockPhpStorage',
       'directory' => 'tmp://',
       'secret' => $this->randomString(),
       'bin' => 'test',