diff --git a/core/includes/config.inc b/core/includes/config.inc
index 0771d60..d1e7183 100644
--- a/core/includes/config.inc
+++ b/core/includes/config.inc
@@ -26,7 +26,7 @@ function config_install_default_config($module) {
     $database_storage = new DatabaseStorage();
     $module_file_storage = new FileStorage(array('directory' => $module_config_dir));
 
-    foreach ($module_file_storage->getNamesWithPrefix() as $config_name) {
+    foreach ($module_file_storage->listAll() as $config_name) {
       $data = $module_file_storage->read($config_name);
       $database_storage->write($config_name, $data);
     }
@@ -38,7 +38,7 @@ function config_install_default_config($module) {
  */
 function config_get_storage_names_with_prefix($prefix = '') {
   $storage = new DatabaseStorage();
-  return $storage->getNamesWithPrefix($prefix);
+  return $storage->listAll($prefix);
 }
 
 /**
@@ -73,8 +73,8 @@ function config($name) {
  *   storage, or FALSE if there are no differences.
  */
 function config_sync_get_changes(StorageInterface $source_storage, StorageInterface $target_storage) {
-  $source_names = $source_storage->getNamesWithPrefix();
-  $target_names = $target_storage->getNamesWithPrefix();
+  $source_names = $source_storage->listAll();
+  $target_names = $target_storage->listAll();
   $config_changes = array(
     'create' => array_diff($source_names, $target_names),
     'change' => array(),
@@ -176,7 +176,7 @@ function config_import_invoke_sync_hooks(array $config_changes) {
   // @todo Leverage DI + config.storage.info.
   $source_storage = new FileStorage();
   $target_storage = new DatabaseStorage();
-  $storage_manager = drupal_container()->get('config.storage.manager');
+  $storage_dispatcher = drupal_container()->get('config.storage.dispatcher');
 
   // Allow modules to take over configuration change operations for
   // higher-level configuration data.
@@ -190,21 +190,17 @@ function config_import_invoke_sync_hooks(array $config_changes) {
       // handle the configuration change.
       $handled_by_module = FALSE;
       if (module_hook($module, 'config_import')) {
-        $old_config = new Config($storage_manager);
-        $old_config->setName($name);
-        try {
-          $old_config->load();
-        }
-        catch (ConfigException $e) {
-        }
-        try {
-          $data = $source_storage->read($name);
-        }
-        catch (ConfigException $e) {
-          $data = array();
-        }
-        $new_config = new Config($storage_manager);
-        $new_config->setName($name)->setData($data);
+        $old_config = new Config($storage_dispatcher);
+        $old_config
+          ->setName($name)
+          ->load();
+
+        $data = $source_storage->read($name);
+        $new_config = new Config($storage_dispatcher);
+        $new_config
+          ->setName($name)
+          ->setData($data);
+
         $handled_by_module = module_invoke($module, 'config_import', $op, $name, $new_config, $old_config);
       }
       if (!empty($handled_by_module)) {
diff --git a/core/includes/install.inc b/core/includes/install.inc
index 32c9941..cd67257 100644
--- a/core/includes/install.inc
+++ b/core/includes/install.inc
@@ -384,7 +384,7 @@ function drupal_uninstall_modules($module_list = array(), $uninstall_dependents
     drupal_uninstall_schema($module);
 
     // Remove all configuration belonging to the module.
-    $config_names = $storage->getNamesWithPrefix($module . '.');
+    $config_names = $storage->listAll($module . '.');
     foreach ($config_names as $config_name) {
       config($config_name)->delete();
     }
diff --git a/core/includes/update.inc b/core/includes/update.inc
index a1bd480..ab373cd 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -10,6 +10,7 @@
 
 use Drupal\Component\Graph\Graph;
 use Drupal\Core\Config\FileStorage;
+use Drupal\Core\Config\ConfigException;
 
 /**
  * Minimum schema version of Drupal 7 required for upgrade to Drupal 8.
@@ -942,9 +943,10 @@ function update_variables_to_config($config_name, array $variable_map) {
   $module = strtok($config_name, '.');
 
   // Load and set default configuration values.
-  // Throws a StorageException if there is no default configuration file, which
-  // is required to exist.
   $file = new FileStorage(array('directory' => drupal_get_path('module', $module) . '/config'));
+  if (!$file->exists($config_name)) {
+    throw new ConfigException("Default configuration file $config_name for $module extension not found but is required to exist.");
+  }
   $default_data = $file->read($config_name);
 
   // Merge any possibly existing original data into default values.
diff --git a/core/lib/Drupal/Core/Config/Config.php b/core/lib/Drupal/Core/Config/Config.php
index 7eb2d6c..0748b76 100644
--- a/core/lib/Drupal/Core/Config/Config.php
+++ b/core/lib/Drupal/Core/Config/Config.php
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Definition of Drupal\Core\Config\Config.
+ */
+
 namespace Drupal\Core\Config;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/ConfigException.php b/core/lib/Drupal/Core/Config/ConfigException.php
index 8a81b6e..5e7daed 100644
--- a/core/lib/Drupal/Core/Config/ConfigException.php
+++ b/core/lib/Drupal/Core/Config/ConfigException.php
@@ -10,6 +10,6 @@ namespace Drupal\Core\Config;
 use RuntimeException;
 
 /**
- * A base exception to the thrown in any configuration system operations.
+ * A base exception thrown in any configuration system operations.
  */
 class ConfigException extends RuntimeException {}
diff --git a/core/lib/Drupal/Core/Config/DatabaseStorage.php b/core/lib/Drupal/Core/Config/DatabaseStorage.php
index cb1d925..162fd46 100644
--- a/core/lib/Drupal/Core/Config/DatabaseStorage.php
+++ b/core/lib/Drupal/Core/Config/DatabaseStorage.php
@@ -1,8 +1,12 @@
 <?php
 
+/**
+ * @file
+ * Definition of Drupal\Core\Config\DatabaseStorage.
+ */
+
 namespace Drupal\Core\Config;
 
-use Drupal\Core\Config\StorageInterface;
 use Drupal\Core\Database\Database;
 use Exception;
 
@@ -21,7 +25,7 @@ class DatabaseStorage implements StorageInterface {
   protected $options;
 
   /**
-   * Implements StorageInterface::__construct().
+   * Implements Drupal\Core\Config\StorageInterface::__construct().
    */
   public function __construct(array $options = array()) {
     $options += array(
@@ -38,14 +42,20 @@ class DatabaseStorage implements StorageInterface {
   }
 
   /**
-   * Implements StorageInterface::read().
+   * Implements Drupal\Core\Config\StorageInterface::read().
+   *
+   * @throws PDOException
+   * @throws Drupal\Core\Database\DatabaseExceptionWrapper
+   *   Only thrown in case $this->options['throw_exception'] is TRUE.
    */
   public function read($name) {
+    $data = array();
     // There are situations, like in the installer, where we may attempt a
     // read without actually having the database available. In this case,
     // catch the exception and just return an empty array so the caller can
     // handle it if need be.
-    $data = array();
+    // @todo Remove this and use appropriate StorageDispatcher configuration in
+    //   the installer instead.
     try {
       $raw = $this->getConnection()->query('SELECT data FROM {config} WHERE name = :name', array(':name' => $name), $this->options)->fetchField();
       if ($raw !== FALSE) {
@@ -58,43 +68,57 @@ class DatabaseStorage implements StorageInterface {
   }
 
   /**
-   * Implements StorageInterface::write().
+   * Implements Drupal\Core\Config\StorageInterface::write().
+   *
+   * @throws PDOException
    */
   public function write($name, array $data) {
     $data = $this->encode($data);
-    return $this->getConnection()->merge('config', $this->options)
+    $options = array('return' => Database::RETURN_AFFECTED) + $this->options;
+    return (bool) $this->getConnection()->merge('config', $options)
       ->key(array('name' => $name))
       ->fields(array('data' => $data))
       ->execute();
   }
 
   /**
-   * Implements StorageInterface::delete().
+   * Implements Drupal\Core\Config\StorageInterface::delete().
+   *
+   * @throws PDOException
    */
   public function delete($name) {
-    $this->getConnection()->delete('config', $this->options)
+    $options = array('return' => Database::RETURN_AFFECTED) + $this->options;
+    return (bool) $this->getConnection()->delete('config', $options)
       ->condition('name', $name)
       ->execute();
   }
 
   /**
-   * Implements StorageInterface::encode().
+   * Implements Drupal\Core\Config\StorageInterface::encode().
    */
   public static function encode($data) {
     return serialize($data);
   }
 
   /**
-   * Implements StorageInterface::decode().
+   * Implements Drupal\Core\Config\StorageInterface::decode().
+   *
+   * @throws ErrorException
+   *   unserialize() triggers E_NOTICE if the string cannot be unserialized.
    */
   public static function decode($raw) {
-    return unserialize($raw);
+    $data = @unserialize($raw);
+    return $data !== FALSE ? $data : array();
   }
 
   /**
-   * Implements StorageInterface::getNamesWithPrefix().
+   * Implements Drupal\Core\Config\StorageInterface::listAll().
+   *
+   * @throws PDOException
+   * @throws Drupal\Core\Database\DatabaseExceptionWrapper
+   *   Only thrown in case $this->options['throw_exception'] is TRUE.
    */
-  public function getNamesWithPrefix($prefix = '') {
+  public function listAll($prefix = '') {
     return $this->getConnection()->query('SELECT name FROM {config} WHERE name LIKE :name', array(
       ':name' => db_like($prefix) . '%',
     ), $this->options)->fetchCol();
diff --git a/core/lib/Drupal/Core/Config/FileStorage.php b/core/lib/Drupal/Core/Config/FileStorage.php
index bafd099..cee29ae 100644
--- a/core/lib/Drupal/Core/Config/FileStorage.php
+++ b/core/lib/Drupal/Core/Config/FileStorage.php
@@ -1,8 +1,12 @@
 <?php
 
+/**
+ * @file
+ * Definition of Drupal\Core\Config\FileStorage.
+ */
+
 namespace Drupal\Core\Config;
 
-use Drupal\Core\Config\StorageInterface;
 use Symfony\Component\Yaml\Yaml;
 
 /**
@@ -20,7 +24,7 @@ class FileStorage implements StorageInterface {
   protected $options;
 
   /**
-   * Implements StorageInterface::__construct().
+   * Implements Drupal\Core\Config\StorageInterface::__construct().
    */
   public function __construct(array $options = array()) {
     if (!isset($options['directory'])) {
@@ -60,47 +64,57 @@ class FileStorage implements StorageInterface {
   }
 
   /**
-   * Implements StorageInterface::write().
-   *
-   * @throws StorageException
-   */
-  public function write($name, array $data) {
-    $data = $this->encode($data);
-    if (!file_put_contents($this->getFilePath($name), $data)) {
-      throw new StorageException('Failed to write configuration file: ' . $this->getFilePath($name));
-    }
-    return $this;
-  }
-
-  /**
-   * Implements StorageInterface::read().
+   * Implements Drupal\Core\Config\StorageInterface::read().
    *
-   * @throws StorageException
+   * @throws Symfony\Component\Yaml\Exception\ParseException
    */
   public function read($name) {
-    // @todo DatabaseStorage does not throw an exception if $name does not exist.
     if (!$this->exists($name)) {
-      throw new StorageException("Configuration file '$name' does not exist.");
+      return array();
     }
-
     $data = file_get_contents($this->getFilePath($name));
+    // @todo Yaml throws a ParseException on invalid data. Is it expected to be
+    //   caught or not?
     $data = $this->decode($data);
     if ($data === FALSE) {
-      throw new StorageException("Failed to decode configuration file '$name'.");
+      return array();
+    }
+    // A simple string is valid YAML for any reason.
+    if (!is_array($data)) {
+      return array();
     }
     return $data;
   }
 
   /**
-   * Deletes a configuration file.
+   * Implements Drupal\Core\Config\StorageInterface::write().
+   *
+   * @throws Symfony\Component\Yaml\Exception\DumpException
+   * @throws Drupal\Core\Config\StorageException
+   */
+  public function write($name, array $data) {
+    $data = $this->encode($data);
+    $status = file_put_contents($this->getFilePath($name), $data);
+    if ($status === FALSE) {
+      throw new StorageException('Failed to write configuration file: ' . $this->getFilePath($name));
+    }
+    return TRUE;
+  }
+
+  /**
+   * Implements Drupal\Core\Config\StorageInterface::delete().
    */
   public function delete($name) {
-    // @todo Error handling.
-    return @drupal_unlink($this->getFilePath($name));
+    if (!$this->exists($name)) {
+      return FALSE;
+    }
+    return drupal_unlink($this->getFilePath($name));
   }
 
   /**
-   * Implements StorageInterface::encode().
+   * Implements Drupal\Core\Config\StorageInterface::encode().
+   *
+   * @throws Symfony\Component\Yaml\Exception\DumpException
    */
   public static function encode($data) {
     // The level where you switch to inline YAML is set to PHP_INT_MAX to ensure
@@ -109,7 +123,9 @@ class FileStorage implements StorageInterface {
   }
 
   /**
-   * Implements StorageInterface::decode().
+   * Implements Drupal\Core\Config\StorageInterface::decode().
+   *
+   * @throws Symfony\Component\Yaml\Exception\ParseException
    */
   public static function decode($raw) {
     if (empty($raw)) {
@@ -119,11 +135,14 @@ class FileStorage implements StorageInterface {
   }
 
   /**
-   * Implements StorageInterface::getNamesWithPrefix().
+   * Implements Drupal\Core\Config\StorageInterface::listAll().
    */
-  public function getNamesWithPrefix($prefix = '') {
+  public function listAll($prefix = '') {
     $extension = '.' . self::getFileExtension();
     $files = glob($this->options['directory'] . '/' . $prefix . '*' . $extension);
+    if ($files === FALSE) {
+      return array();
+    }
     $clean_name = function ($value) use ($extension) {
       return basename($value, $extension);
     };
diff --git a/core/lib/Drupal/Core/Config/StorageDispatcher.php b/core/lib/Drupal/Core/Config/StorageDispatcher.php
index 9e14c73..ebf7049 100644
--- a/core/lib/Drupal/Core/Config/StorageDispatcher.php
+++ b/core/lib/Drupal/Core/Config/StorageDispatcher.php
@@ -76,6 +76,11 @@ class StorageDispatcher {
    * @param string $name
    *   The name of the configuration object that is operated on.
    *
+   * @return Drupal\Core\Config\StorageInterface
+   *   The storage controller instance that can handle the requested operation.
+   *
+   * @throws Drupal\Core\Config\ConfigException
+   *
    * @todo Allow write operations to write to multiple storages.
    */
   public function selectStorage($access_operation, $name) {
diff --git a/core/lib/Drupal/Core/Config/StorageException.php b/core/lib/Drupal/Core/Config/StorageException.php
index 8fddd17..a956fea 100644
--- a/core/lib/Drupal/Core/Config/StorageException.php
+++ b/core/lib/Drupal/Core/Config/StorageException.php
@@ -10,6 +10,6 @@ namespace Drupal\Core\Config;
 use Drupal\Core\Config\ConfigException;
 
 /**
- * An exception to be thrown in case of storage controller operation errors.
+ * An exception thrown in case of storage controller operation errors.
  */
 class StorageException extends ConfigException {}
diff --git a/core/lib/Drupal/Core/Config/StorageInterface.php b/core/lib/Drupal/Core/Config/StorageInterface.php
index 6ad1c11..907e884 100644
--- a/core/lib/Drupal/Core/Config/StorageInterface.php
+++ b/core/lib/Drupal/Core/Config/StorageInterface.php
@@ -1,9 +1,14 @@
 <?php
 
+/**
+ * @file
+ * Definition of Drupal\Core\Config\StorageInterface.
+ */
+
 namespace Drupal\Core\Config;
 
 /**
- * Defines an interface for configuration storage manipulation.
+ * Defines an interface for configuration storage controllers.
  *
  * Classes implementing this interface allow reading and writing configuration
  * data from and to the storage.
@@ -24,6 +29,10 @@ interface StorageInterface {
    *
    * @param string $name
    *   The name of a configuration object to load.
+   *
+   * @return array
+   *   The configuration data stored for the configuration object name. If no
+   *   configuration data exists for the given name, an empty array is returned.
    */
   public function read($name);
 
@@ -34,6 +43,9 @@ interface StorageInterface {
    *   The name of a configuration object to save.
    * @param array $data
    *   The configuration data to write.
+   *
+   * @return bool
+   *   TRUE on success, FALSE in case of an error.
    */
   public function write($name, array $data);
 
@@ -42,6 +54,9 @@ interface StorageInterface {
    *
    * @param string $name
    *   The name of a configuration object to delete.
+   *
+   * @return bool
+   *   TRUE on success, FALSE otherwise.
    */
   public function delete($name);
 
@@ -80,7 +95,7 @@ interface StorageInterface {
    * - node.type.article
    * - node.type.page
    *
-   * Passing the prefix 'node.type' will return an array containing the above
+   * Passing the prefix 'node.type.' will return an array containing the above
    * names.
    *
    * @param string $prefix
@@ -90,5 +105,5 @@ interface StorageInterface {
    * @return array
    *   An array containing matching configuration object names.
    */
-  public function getNamesWithPrefix($prefix = '');
+  public function listAll($prefix = '');
 }
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigFileContentTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigFileContentTest.php
index 29fad3e..3add6d8 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigFileContentTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigFileContentTest.php
@@ -157,22 +157,22 @@ class ConfigFileContentTest extends WebTestBase {
 
     // Get file listing for all files starting with 'foo'. Should return
     // two elements.
-    $files = $database_storage->getNamesWithPrefix('foo');
+    $files = $database_storage->listAll('foo');
     $this->assertEqual(count($files), 2, 'Two files listed with the prefix \'foo\'.');
 
     // Get file listing for all files starting with 'biff'. Should return
     // one element.
-    $files = $database_storage->getNamesWithPrefix('biff');
+    $files = $database_storage->listAll('biff');
     $this->assertEqual(count($files), 1, 'One file listed with the prefix \'biff\'.');
 
     // Get file listing for all files starting with 'foo.bar'. Should return
     // one element.
-    $files = $database_storage->getNamesWithPrefix('foo.bar');
+    $files = $database_storage->listAll('foo.bar');
     $this->assertEqual(count($files), 1, 'One file listed with the prefix \'foo.bar\'.');
 
     // Get file listing for all files starting with 'bar'. Should return
     // an empty array.
-    $files = $database_storage->getNamesWithPrefix('bar');
+    $files = $database_storage->listAll('bar');
     $this->assertEqual($files, array(), 'No files listed with the prefix \'bar\'.');
 
     // Delete the configuration.
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigUpgradeTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigUpgradeTest.php
index b2286da..0b43de4 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigUpgradeTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigUpgradeTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\config\Tests;
 
+use Drupal\Core\Config\ConfigException;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -80,5 +81,14 @@ class ConfigUpgradeTest extends WebTestBase {
     // Verify that variables have been deleted.
     $variables = db_query('SELECT name FROM {variable} WHERE name IN (:names)', array(':names' => array('config_upgrade_additional')))->fetchCol();
     $this->assertFalse($variables);
+
+    // Verify that a default module configuration file is required to exist.
+    try {
+      update_variables_to_config('config_upgrade.missing.default.config', array());
+      $this->fail('Exception was not thrown on missing default module configuration file.');
+    }
+    catch (ConfigException $e) {
+      $this->pass('Exception was thrown on missing default module configuration file.');
+    }
   }
 }
diff --git a/core/modules/config/lib/Drupal/config/Tests/Storage/ConfigStorageTestBase.php b/core/modules/config/lib/Drupal/config/Tests/Storage/ConfigStorageTestBase.php
new file mode 100644
index 0000000..15ccb90
--- /dev/null
+++ b/core/modules/config/lib/Drupal/config/Tests/Storage/ConfigStorageTestBase.php
@@ -0,0 +1,118 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\config\Tests\Storage\ConfigStorageTestBase.
+ */
+
+namespace Drupal\config\Tests\Storage;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Base class for testing storage controller operations.
+ *
+ * All configuration storage controllers are expected to behave identically in
+ * terms of reading, writing, listing, deleting, as well as error handling.
+ *
+ * Therefore, storage controller tests use a uncommon test case class structure;
+ * the base class defines the test method(s) to execute, which are identical for
+ * all storage controllers. The storage controller specific test case classes
+ * supply the necessary helper methods to interact with the raw/native storage
+ * directly.
+ */
+abstract class ConfigStorageTestBase extends WebTestBase {
+
+  /**
+   * Tests storage controller CRUD operations.
+   *
+   * @todo Coverage: Trigger PDOExceptions / Database exceptions.
+   * @todo Coverage: Trigger Yaml's ParseException and DumpException.
+   */
+  function testCRUD() {
+    $name = 'config_test.storage';
+
+    // Reading a non-existing name returns an empty data array.
+    $data = $this->storage->read($name);
+    $this->assertIdentical($data, array());
+
+    // Reading a name containing non-decodeable data returns an empty array.
+    $this->insert($name, '');
+    $data = $this->storage->read($name);
+    $this->assertIdentical($data, array());
+
+    $this->update($name, 'foo');
+    $data = $this->storage->read($name);
+    $this->assertIdentical($data, array());
+
+    $this->delete($name);
+
+    // Writing data returns TRUE and the data has been written.
+    $data = array('foo' => 'bar');
+    $result = $this->storage->write($name, $data);
+    $this->assertIdentical($result, TRUE);
+    $raw_data = $this->read($name);
+    $this->assertIdentical($raw_data, $data);
+
+    // Writing the identical data again still returns TRUE.
+    $result = $this->storage->write($name, $data);
+    $this->assertIdentical($result, TRUE);
+
+    // Listing all names returns all.
+    $names = $this->storage->listAll();
+    $this->assertTrue(in_array('system.performance', $names));
+    $this->assertTrue(in_array($name, $names));
+
+    // Listing all names with prefix returns names with that prefix only.
+    $names = $this->storage->listAll('config_test.');
+    $this->assertFalse(in_array('system.performance', $names));
+    $this->assertTrue(in_array($name, $names));
+
+    // Deleting an existing name returns TRUE.
+    $result = $this->storage->delete($name);
+    $this->assertIdentical($result, TRUE);
+
+    // Deleting a non-existing name returns FALSE.
+    $result = $this->storage->delete($name);
+    $this->assertIdentical($result, FALSE);
+
+    // Reading from a non-existing storage bin returns an empty data array.
+    $data = $this->invalidStorage->read($name);
+    $this->assertIdentical($data, array());
+
+    // Writing to a non-existing storage bin throws an exception.
+    try {
+      $this->invalidStorage->write($name, array('foo' => 'bar'));
+      $this->fail('Exception not thrown upon writing to a non-existing storage bin.');
+    }
+    catch (\Exception $e) {
+      $this->pass('Exception thrown upon writing to a non-existing storage bin.');
+    }
+
+    // Deleting from a non-existing storage bin throws an exception.
+    try {
+      $this->invalidStorage->delete($name);
+      $this->fail('Exception not thrown upon deleting from a non-existing storage bin.');
+    }
+    catch (\Exception $e) {
+      $this->pass('Exception thrown upon deleting from a non-existing storage bin.');
+    }
+
+    // Listing on a non-existing storage bin throws an exception.
+    try {
+      $this->invalidStorage->listAll();
+      $this->fail('Exception not thrown upon listing from a non-existing storage bin.');
+    }
+    catch (\Exception $e) {
+      $this->pass('Exception thrown upon listing from a non-existing storage bin.');
+    }
+  }
+
+  abstract protected function read($name);
+
+  abstract protected function insert($name, $data);
+
+  abstract protected function update($name, $data);
+
+  abstract protected function delete($name);
+}
diff --git a/core/modules/config/lib/Drupal/config/Tests/Storage/DatabaseStorageTest.php b/core/modules/config/lib/Drupal/config/Tests/Storage/DatabaseStorageTest.php
new file mode 100644
index 0000000..6fa1094
--- /dev/null
+++ b/core/modules/config/lib/Drupal/config/Tests/Storage/DatabaseStorageTest.php
@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\config\Tests\Storage\DatabaseStorageTest.
+ */
+
+namespace Drupal\config\Tests\Storage;
+
+use Drupal\Core\Config\DatabaseStorage;
+
+/**
+ * Tests DatabaseStorage controller operations.
+ */
+class DatabaseStorageTest extends ConfigStorageTestBase {
+  public static function getInfo() {
+    return array(
+      'name' => 'DatabaseStorage controller operations',
+      'description' => 'Tests DatabaseStorage controller operations.',
+      'group' => 'Configuration',
+    );
+  }
+
+  function setUp() {
+    parent::setUp();
+    $this->storage = new DatabaseStorage();
+    $this->invalidStorage = new DatabaseStorage(array('target' => 'invalid'));
+  }
+
+  protected function read($name) {
+    $data = db_query('SELECT data FROM {config} WHERE name = :name', array(':name' => $name))->fetchField();
+    return unserialize($data);
+  }
+
+  protected function insert($name, $data) {
+    db_insert('config')->fields(array('name' => $name, 'data' => $data))->execute();
+  }
+
+  protected function update($name, $data) {
+    db_update('config')->fields(array('data' => $data))->condition('name', $name)->execute();
+  }
+
+  protected function delete($name) {
+    db_delete('config')->condition('name', $name)->execute();
+  }
+}
diff --git a/core/modules/config/lib/Drupal/config/Tests/Storage/FileStorageTest.php b/core/modules/config/lib/Drupal/config/Tests/Storage/FileStorageTest.php
new file mode 100644
index 0000000..092687f
--- /dev/null
+++ b/core/modules/config/lib/Drupal/config/Tests/Storage/FileStorageTest.php
@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\config\Tests\Storage\FileStorageTest.
+ */
+
+namespace Drupal\config\Tests\Storage;
+
+use Drupal\Core\Config\FileStorage;
+use Symfony\Component\Yaml\Yaml;
+
+/**
+ * Tests FileStorage controller operations.
+ */
+class FileStorageTest extends ConfigStorageTestBase {
+  public static function getInfo() {
+    return array(
+      'name' => 'FileStorage controller operations',
+      'description' => 'Tests FileStorage controller operations.',
+      'group' => 'Configuration',
+    );
+  }
+
+  function setUp() {
+    parent::setUp();
+    $this->storage = new FileStorage();
+    $this->invalidStorage = new FileStorage(array('directory' => $this->configFileDirectory . '/nonexisting'));
+
+    // FileStorage::listAll() requires other configuration data to exist.
+    $this->storage->write('system.performance', config('system.performance')->get());
+  }
+
+  protected function read($name) {
+    $data = file_get_contents($this->storage->getFilePath($name));
+    return Yaml::parse($data);
+  }
+
+  protected function insert($name, $data) {
+    file_put_contents($this->storage->getFilePath($name), $data);
+  }
+
+  protected function update($name, $data) {
+    file_put_contents($this->storage->getFilePath($name), $data);
+  }
+
+  protected function delete($name) {
+    unlink($this->storage->getFilePath($name));
+  }
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
index 2c0712f..8f372ca 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
@@ -92,7 +92,7 @@ class ModuleTestBase extends WebTestBase {
       return;
     }
     $module_file_storage = new FileStorage(array('directory' => $module_config_dir));
-    $names = $module_file_storage->getNamesWithPrefix();
+    $names = $module_file_storage->listAll();
 
     // Verify that the config directory is not empty.
     $this->assertTrue($names);