diff --git a/core/core.services.yml b/core/core.services.yml
index 784d964..4d64d44 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1207,17 +1207,14 @@ services:
       - { name: stream_wrapper, scheme: temporary }
   stream_wrapper.module:
     class: Drupal\Core\StreamWrapper\ModuleStream
-    arguments: ['@request_stack', '@module_handler']
     tags:
       - { name: stream_wrapper, scheme: module }
   stream_wrapper.theme:
     class: Drupal\Core\StreamWrapper\ThemeStream
-    arguments: ['@request_stack', '@theme_handler', '@theme.negotiator', '@config.factory', '@current_route_match']
     tags:
       - { name: stream_wrapper, scheme: theme }
   stream_wrapper.profile:
     class: Drupal\Core\StreamWrapper\ProfileStream
-    arguments: ['@request_stack']
     tags:
       - { name: stream_wrapper, scheme: profile }
   kernel_destruct_subscriber:
diff --git a/core/lib/Drupal/Core/StreamWrapper/LocalStream.php b/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
index 490abcd..1b1e371 100644
--- a/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
@@ -62,14 +62,14 @@ public static function getType() {
   /**
    * Implements Drupal\Core\StreamWrapper\StreamWrapperInterface::setUri().
    */
-  public function setUri($uri) {
+  function setUri($uri) {
     $this->uri = $uri;
   }
 
   /**
    * Implements Drupal\Core\StreamWrapper\StreamWrapperInterface::getUri().
    */
-  public function getUri() {
+  function getUri() {
     return $this->uri;
   }
 
@@ -578,5 +578,4 @@ public function dir_closedir() {
     // have a return value.
     return TRUE;
   }
-
 }
diff --git a/core/lib/Drupal/Core/StreamWrapper/ModuleStream.php b/core/lib/Drupal/Core/StreamWrapper/ModuleStream.php
index 0a878a3..3424c56 100644
--- a/core/lib/Drupal/Core/StreamWrapper/ModuleStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/ModuleStream.php
@@ -24,15 +24,10 @@ class ModuleStream extends SystemStream {
 
   /**
    * Constructs a ModuleStream wrapper object.
-   *
-   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
-   *   The request stack from which the current request is retrieved.
-   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
-   *   The module handler.
    */
-  public function __construct(RequestStack $request_stack, ModuleHandlerInterface $module_handler) {
-    parent::__construct($request_stack);
-    $this->moduleHandler = $module_handler;
+  public function __construct() {
+    parent::__construct();
+    $this->moduleHandler = \Drupal::moduleHandler();
   }
 
   /**
diff --git a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
index ea2297a..7c1c190 100644
--- a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
+++ b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
@@ -67,7 +67,6 @@
 
   /**
    * Not visible in the UI or accessible via web, but readable and writable.
-   *
    * E.g. the temporary directory for uploads.
    */
   const HIDDEN = 0x000C;
diff --git a/core/lib/Drupal/Core/StreamWrapper/SystemStream.php b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
index a4d96a8..5bb3ca5 100644
--- a/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
@@ -25,12 +25,9 @@
 
   /**
    * Constructs a new system stream.
-   *
-   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
-   *   The request stack from which the current request is retrieved.
    */
-  public function __construct(RequestStack $request_stack) {
-    $this->request = $request_stack->getCurrentRequest();
+  public function __construct() {
+    $this->request = \Drupal::service('request_stack')->getCurrentRequest();
   }
 
   /**
diff --git a/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php b/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
index a02b01a..3a60f0f 100644
--- a/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
@@ -48,24 +48,13 @@ class ThemeStream extends SystemStream {
 
   /**
    * Constructs a new ThemeStream object.
-   *
-   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
-   *   The request stack from which the current request is retrieved.
-   * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
-   *   The theme handler.
-   * @param \Drupal\Core\Theme\ThemeNegotiatorInterface $theme_negotiator
-   *   The theme negotiator.
-   * @param \Drupal\Core\Config\ConfigFactoryInterface $config
-   *   The config manager.
-   * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
-   *   The route matcher.
    */
-  public function __construct(RequestStack $request_stack, ThemeHandlerInterface $theme_handler, ThemeNegotiatorInterface $theme_negotiator, ConfigFactoryInterface $config, RouteMatchInterface $route_match) {
-    parent::__construct($request_stack);
-    $this->themeHandler = $theme_handler;
-    $this->themeNegotiator = $theme_negotiator;
-    $this->configFactory = $config;
-    $this->routeMatch = $route_match;
+  public function __construct() {
+    parent::__construct();
+    $this->themeHandler = \Drupal::service('theme_handler');
+    $this->themeNegotiator = \Drupal::service('theme.negotiator');
+    $this->configFactory = \Drupal::configFactory();
+    $this->routeMatch = \Drupal::service('current_route_match');
   }
 
   /**
@@ -77,15 +66,12 @@ protected function getOwnerName() {
       case 'current':
         $name = $this->getActiveTheme();
         break;
-
       case 'default':
         $name = $this->themeHandler->getDefault();
         break;
-
       case 'admin':
         $name = $this->configFactory->get('system.theme')->get('admin');
         break;
-
     }
     // Return name only for installed themes.
     if ($this->themeHandler->themeExists($name)) {
diff --git a/core/modules/system/src/Tests/File/SystemStreamTest.php b/core/modules/system/src/Tests/File/SystemStreamTest.php
index 1f7d42f..5d4d505 100644
--- a/core/modules/system/src/Tests/File/SystemStreamTest.php
+++ b/core/modules/system/src/Tests/File/SystemStreamTest.php
@@ -9,58 +9,55 @@
 
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Site\Settings;
+use Drupal\Core\StreamWrapper\StreamWrapperInterface;
 use Drupal\simpletest\KernelTestBase;
 
 /**
- * Unit tests for system stream wrapper functions.
+ * Tests system stream wrapper functions.
  *
  * @group system
  */
 class SystemStreamTest extends KernelTestBase {
 
   /**
-   * Modules to install for this test.
-   *
-   * @var array
+   * {@inheritdoc}
    */
-  public static $modules = array('system', 'file', 'file_test');
+  public static $modules = ['system', 'file', 'file_test'];
 
   /**
-   * The profile to install as a basis for testing.
+   * The stream wrapper manager service.
    *
-   * @var string
-   */
-  protected $profile = 'standard';
-
-  /**
-   * {@inheritdoc}
+   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
    */
-  public static function getInfo() {
-    return array(
-      'name' => 'System Stream wrappers',
-      'description' => 'Unit tests system stream wrapper functions.',
-      'group' => 'File API',
-    );
-  }
+  protected $streamWrapperManager;
 
   /**
    * {@inheritdoc}
    */
   public function setUp() {
     parent::setUp();
-    drupal_static_reset('file_get_stream_wrappers');
 
+    drupal_static_reset('file_get_stream_wrappers');
+    $this->streamWrapperManager = $this->container->get('stream_wrapper_manager');
+
+    /** @var \Drupal\Core\State\StateInterface $state */
+    $state = $this->container->get('state');
+    // Add 'minimal' profile to 'system.module.files' state to allow
+    // drupal_get_profile() to get the profile from state. drupal_get_profile()
+    // resolves only the current profile but reads also profiles from states.
+    // @see drupal_get_profile()
+    $system_module_files = $state->get('system.module.files', []);
+    $system_module_files += ['minimal' => 'core/profiles/minimal/minimal.info.yml'];
+    $state->set('system.module.files', $system_module_files);
     // Add default profile for the purposes of this test.
-//    new Settings(Settings::getAll() + array(
-//      'install_profile' => 'standard'
-//    ));
+    new Settings(Settings::getAll() +  ['install_profile' => 'minimal']);
   }
 
   /**
    * Test Invalid stream uri.
    */
   public function testInvalidStreamUriException() {
-    $bad_uris = array(
+    $bad_uris = [
       'invalid/uri',
       'invalid_uri',
       'module/invalid/uri',
@@ -71,19 +68,18 @@ public function testInvalidStreamUriException() {
       'module//:invalid/uri',
       'module//invalid_uri',
       'module//invalid/uri',
-    );
+    ];
 
-    /** @var \Drupal\Core\StreamWrapper\ModuleStream $instance */
-    $instance = \Drupal::service('stream_wrapper_manager')->getViaScheme('module');
+    $instance = $this->streamWrapperManager->getViaScheme('module');
 
     foreach ($bad_uris as $bad_uri) {
       try {
         $instance->dirname($bad_uri);
-        $this->fail(SafeMarkup::format('Invalid uri %uri not detected.', array('%uri' => $bad_uri)));
+        $this->fail(SafeMarkup::format('Invalid uri %uri not detected.', ['%uri' => $bad_uri]));
       }
       catch (\InvalidArgumentException $e) {
         if ($e->getMessage() == 'Malformed uri parameter passed: ' . $bad_uri) {
-          $this->pass(SafeMarkup::format('Throw exception on invalid uri %uri supplied.', array('%uri' => $bad_uri)));
+          $this->pass(SafeMarkup::format('Throw exception on invalid uri %uri supplied.', ['%uri' => $bad_uri]));
         }
         else {
           throw new \InvalidArgumentException($e);
@@ -97,66 +93,68 @@ public function testInvalidStreamUriException() {
    */
   public function testModuleStream() {
     // Generate a module stream wrapper instance.
-    /** @var \Drupal\Core\StreamWrapper\ModuleStream $instance */
-    $instance = \Drupal::service('stream_wrapper_manager')->getViaScheme('module');
+    $instance = $this->streamWrapperManager->getViaScheme('module');
 
-    // dirname()
-    $data = $this->providerModuleStream('dirname');
+    // Test dirname().
+    $data = $this->moduleStreamTestCasesProvider('dirname');
     $this->runTestOnInstanceMethod($instance, 'dirname', $data);
 
-    // realpath()
-    $data = $this->providerModuleStream('realpath');
+    // Test realpath().
+    $data = $this->moduleStreamTestCasesProvider('realpath');
     $this->runTestOnInstanceMethod($instance, 'realpath', $data);
 
-    // getExternalUrl()
-    $data = $this->providerModuleStream('getExternalUrl');
+    // Test getExternalUrl().
+    $data = $this->moduleStreamTestCasesProvider('getExternalUrl');
     $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
   }
 
   /**
-   * Provides test data for testModuleStream().
+   * Provides test cases for testModuleStream().
+   *
+   * @param string $method
+   *   The method to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
    */
-  protected function providerModuleStream($method) {
-    $uris = array(
+  protected function moduleStreamTestCasesProvider($method) {
+    $uris = [
       'module://system',
       'module://system/css/system.admin.css',
       'module://file_test/file_test.dummy.inc',
       'module://file_test/src/file_test.dummy.inc',
       'module://ckeditor/ckeditor.info.yml',
       'module://foo_bar/foo.bar.js',
-    );
+    ];
     switch ($method) {
       case 'dirname':
-        return array_combine($uris, array(
-          array('module://system', 'Get the dirname of an installed module.'),
-          array('module://system/css', 'Get the dirname of a resource located in a subdirectory of an installed module.'),
-          array('module://file_test', 'Get the dirname of a resource in a module located in a subdirectory.'),
-          array('module://file_test/src', 'Get the dirname of a non-existent resource in a subdirectory of a module.'),
-          array(new \InvalidArgumentException(), 'Fail returning an uninstalled module\'s dirname.'),
-          array(new \InvalidArgumentException(), 'Fail returning a non-existent module\'s dirname.'),
-        ));
-
+        return array_combine($uris, [
+          'module://system',
+          'module://system/css',
+          'module://file_test',
+          'module://file_test/src',
+          [new \InvalidArgumentException(), 'Module ckeditor does not exist or is not installed'],
+          [new \InvalidArgumentException(), 'Module foo_bar does not exist or is not installed'],
+        ]);
       case 'realpath':
-        $base_path = DRUPAL_ROOT;
-        return array_combine($uris, array(
-          array($base_path . '/core/modules/system', 'Get the realpath of an installed module.'),
-          array($base_path . '/core/modules/system/css/system.admin.css', 'Get the realpath of a resource located in a subdirectory of an installed module.'),
-          array($base_path . '/core/modules/file/tests/file_test/file_test.dummy.inc', 'Get the realpath of a resource in a module located in a subdirectory.'),
-          array($base_path . '/core/modules/file/tests/file_test/src/file_test.dummy.inc', 'Get the realpath of a non-existent resource in a subdirectory of a module.'),
-          array(new \InvalidArgumentException(), 'Fail returning an uninstalled module\'s basepath.'),
-          array(new \InvalidArgumentException(), 'Fail returning a non-existent module\'s basepath.'),
-        ));
-
+        return array_combine($uris, [
+          DRUPAL_ROOT . '/core/modules/system',
+          DRUPAL_ROOT . '/core/modules/system/css/system.admin.css',
+          DRUPAL_ROOT . '/core/modules/file/tests/file_test/file_test.dummy.inc',
+          DRUPAL_ROOT . '/core/modules/file/tests/file_test/src/file_test.dummy.inc',
+          [new \InvalidArgumentException(), 'Module ckeditor does not exist or is not installed'],
+          [new \InvalidArgumentException(), 'Module foo_bar does not exist or is not installed'],
+        ]);
       case 'getExternalUrl':
         $base_url = \Drupal::request()->getUriForPath(base_path());
-        return array_combine($uris, array(
-          array($base_url . 'core/modules/system', "Return the external url for the module directory path."),
-          array($base_url . 'core/modules/system/css/system.admin.css', "Return the external url of a resource located in a subdirectory."),
-          array($base_url . 'core/modules/file/tests/file_test/file_test.dummy.inc', "Return the external url of an include file located in a subdirectory."),
-          array($base_url . 'core/modules/file/tests/file_test/src/file_test.dummy.inc', "Return the external url even for a non-existent resource, as long as the module exists."),
-          array(new \InvalidArgumentException(), "Fail returning the external uri for resources in a disabled module."),
-          array(new \InvalidArgumentException(), "Fail returning the external uri for resources in a non-existent module."),
-      ));
+        return array_combine($uris, [
+          $base_url . 'core/modules/system',
+          $base_url . 'core/modules/system/css/system.admin.css',
+          $base_url . 'core/modules/file/tests/file_test/file_test.dummy.inc',
+          $base_url . 'core/modules/file/tests/file_test/src/file_test.dummy.inc',
+          [new \InvalidArgumentException(), 'Module ckeditor does not exist or is not installed'],
+          [new \InvalidArgumentException(), 'Module foo_bar does not exist or is not installed'],
+        ]);
     }
   }
 
@@ -165,67 +163,69 @@ protected function providerModuleStream($method) {
    */
   public function testProfileStream() {
     // Generate a profile stream wrapper instance.
-    /** @var \Drupal\Core\StreamWrapper\ProfileStream $instance */
-    $instance = \Drupal::service('stream_wrapper_manager')->getViaScheme('profile');
+    $instance = $this->streamWrapperManager->getViaScheme('profile');
 
-    // dirname()
-    $data = $this->providerProfileStream('dirname');
+    // Test dirname().
+    $data = $this->profileStreamTestCasesProvider('dirname');
     $this->runTestOnInstanceMethod($instance, 'dirname', $data);
 
-    // realpath()
-    $data = $this->providerProfileStream('realpath');
+    // Test realpath().
+    $data = $this->profileStreamTestCasesProvider('realpath');
     $this->runTestOnInstanceMethod($instance, 'realpath', $data);
 
-    // getExternalUrl()
-    $data = $this->providerProfileStream('getExternalUrl');
+    // Test getExternalUrl().
+    $data = $this->profileStreamTestCasesProvider('getExternalUrl');
     $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
   }
 
   /**
-   * Provides test data for testProfileStream().
+   * Provides test cases for testProfileStream().
+   *
+   * @param string $method
+   *   The method to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
    */
-  protected function providerProfileStream($method) {
-    $uris = array(
+  protected function profileStreamTestCasesProvider($method) {
+    $uris = [
       'profile://minimal',
       'profile://minimal/config/install/block.block.stark_login.yml',
       'profile://minimal/config/install/node.type.article.yml',
       'profile://foo_bar/',
       'profile://current',
-      'profile://current/standard.info.yml',
-    );
+      'profile://current/minimal.info.yml',
+    ];
 
     switch ($method) {
       case 'dirname':
-        return array_combine($uris, array(
-          array('profile://minimal', "Get the dirname of an installed profile."),
-          array('profile://minimal/config/install', "Get the dirname of a resource located in a profile's subdirectory."),
-          array('profile://minimal/config/install', "Get the dirname of a non-existent resource in profile's subdirectory."),
-          array(new \InvalidArgumentException(), "Fail returning the dirname of a non-existent profile."),
-          array('profile://standard', SafeMarkup::format('Get the dirname of %current.', array('%current' => 'profile://current'))),
-          array('profile://standard', SafeMarkup::format('Get the dirname of a resource in %current path.', array('%current' => 'profile://current'))),
-        ));
-
+        return array_combine($uris, [
+          'profile://minimal',
+          'profile://minimal/config/install',
+          'profile://minimal/config/install',
+          [new \InvalidArgumentException(), 'Profile foo_bar does not exist'],
+          'profile://minimal',
+          'profile://minimal',
+        ]);
       case 'realpath':
-        $base_path = DRUPAL_ROOT;
-        return array_combine($uris, array(
-          array($base_path . '/core/profiles/minimal', "Get the realpath of an installed profile."),
-          array($base_path . '/core/profiles/minimal/config/install/block.block.stark_login.yml', "Get the realpath of a resource located in a profile's subdirectory."),
-          array($base_path . '/core/profiles/minimal/config/install/node.type.article.yml', "Get the realpath of a non-existent resource in profile's subdirectory."),
-          array(new \InvalidArgumentException(), "Fail returning the realpath for a non-existent profile."),
-          array($base_path . '/core/profiles/standard', SafeMarkup::format('Get the realpath of %current.', array('%current' => 'profile://current'))),
-          array($base_path . '/core/profiles/standard/standard.info.yml', SafeMarkup::format('Get the realpath of a resource in %current path.', array('%current' => 'profile://current'))),
-        ));
-
+        return array_combine($uris, [
+          DRUPAL_ROOT . '/core/profiles/minimal',
+          DRUPAL_ROOT . '/core/profiles/minimal/config/install/block.block.stark_login.yml',
+          DRUPAL_ROOT . '/core/profiles/minimal/config/install/node.type.article.yml',
+          [new \InvalidArgumentException(), 'Profile foo_bar does not exist'],
+          DRUPAL_ROOT . '/core/profiles/minimal',
+          DRUPAL_ROOT . '/core/profiles/minimal/minimal.info.yml',
+        ]);
       case 'getExternalUrl':
         $base_url = \Drupal::request()->getUriForPath(base_path());
-        return array_combine($uris, array(
-          array($base_url . 'core/profiles/minimal', "Return the external url for the profile directory path."),
-          array($base_url . 'core/profiles/minimal/config/install/block.block.stark_login.yml', "Return the external url of a file located in a subdirectory."),
-          array($base_url . 'core/profiles/minimal/config/install/node.type.article.yml', "Return the external url of a non-existent file located in a subdirectory."),
-          array(new \InvalidArgumentException(), "Fail returning the external uri for a disabled profile."),
-          array($base_url . 'core/profiles/standard', SafeMarkup::format('Lookup the external url of %current for a partial URI.', array('%current' => 'profile://current'))),
-          array($base_url . 'core/profiles/standard/standard.info.yml', SafeMarkup::format('Lookup the external url of %current for a resource.', array('%current' => 'profile://current'))),
-        ));
+        return array_combine($uris, [
+          $base_url . 'core/profiles/minimal',
+          $base_url . 'core/profiles/minimal/config/install/block.block.stark_login.yml',
+          $base_url . 'core/profiles/minimal/config/install/node.type.article.yml',
+          [new \InvalidArgumentException(), 'Profile foo_bar does not exist'],
+          $base_url . 'core/profiles/minimal',
+          $base_url . 'core/profiles/minimal/minimal.info.yml',
+        ]);
     }
   }
 
@@ -233,47 +233,56 @@ protected function providerProfileStream($method) {
    * Test the Theme stream wrapper functions.
    */
   public function testThemeStream() {
-    // Generate a theme stream wrapper instance.
-    /** @var \Drupal\Core\Extension\ThemeHandler $theme_handler */
-    $theme_handler = \Drupal::service('theme_handler');
+    /** @var \Drupal\Core\Config\ConfigFactoryInterface $config_factory */
+    $config_factory = $this->container->get('config.factory');
+    /** @var \Drupal\Core\Extension\ThemeInstallerInterface $theme_installer */
+    $theme_installer = $this->container->get('theme_installer');
+    /** @var \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler */
+    $theme_handler = $this->container->get('theme_handler');
 
     // Install Stark, Bartik and Seven themes.
-    $theme_handler->install(array('bartik', 'seven', 'stark'));
+    $theme_installer->install(['bartik', 'seven', 'stark']);
 
     // Set admin theme to Seven.
-    $system_theme = \Drupal::configFactory()->getEditable('system.theme');
-    $this->assertNull($system_theme->get('admin'), 'No admin theme was set.');
+    $system_theme = $config_factory->getEditable('system.theme');
+    $this->assertNull($system_theme->get('admin'));
     $system_theme->set('admin', 'seven')->save();
-    $this->assertEqual($system_theme->get('admin'), 'seven', SafeMarkup::format('Make %seven the admin theme.', array('%seven' => 'Seven')));
+    $this->assertEqual($system_theme->get('admin'), 'seven');
 
     // Set default theme to Bartik.
     $theme_handler->setDefault('bartik');
-    $this->assertEqual($theme_handler->getDefault(), 'bartik', SafeMarkup::format('Make %bartik the default theme.', array('%bartik' => 'Bartik')));
+    $this->assertEqual($theme_handler->getDefault(), 'bartik');
 
     // Uninstall Stark theme.
-    $theme_handler->uninstall(array('stark'));
+    $theme_installer->uninstall(['stark']);
 
-    /** @var \Drupal\Core\StreamWrapper\ThemeStream $instance */
-    $instance = \Drupal::service('stream_wrapper_manager')->getViaScheme('theme');
+    // Generate a theme stream wrapper instance.
+    $instance = $this->streamWrapperManager->getViaScheme('theme');
 
-    // dirname()
-    $data = $this->providerThemeStream('dirname');
+    // Test dirname().
+    $data = $this->themeStreamTestCasesProvider('dirname');
     $this->runTestOnInstanceMethod($instance, 'dirname', $data);
 
-    // realpath()
-    $data = $this->providerThemeStream('realpath');
+    // Test realpath().
+    $data = $this->themeStreamTestCasesProvider('realpath');
     $this->runTestOnInstanceMethod($instance, 'realpath', $data);
 
-    // getExternalUrl()
-    $data = $this->providerThemeStream('getExternalUrl');
+    // Test getExternalUrl().
+    $data = $this->themeStreamTestCasesProvider('getExternalUrl');
     $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
   }
 
   /**
-   * Provides test data for testThemeStream()
+   * Provides test cases for testThemeStream().
+   *
+   * @param string $method
+   *   The method to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
    */
-  protected function providerThemeStream($method) {
-    $uris = array(
+  protected function themeStreamTestCasesProvider($method) {
+    $uris = [
       'theme://seven',
       'theme://seven/style.css',
       'theme://bartik/color/preview.js',
@@ -285,55 +294,52 @@ protected function providerThemeStream($method) {
       'theme://admin',
       'theme://admin/fake.info.yml',
       'theme://stark/stark.info.yml',
-    );
+    ];
 
     switch ($method) {
       case 'dirname':
-        return array_combine($uris, array(
-          array('theme://seven', "Get the dirname of an installed theme."),
-          array('theme://seven', "Get the dirname of a resource located in a theme directory."),
-          array('theme://bartik/color', "Get the dirname of a resource located in a theme's subdirectory."),
-          array(new \InvalidArgumentException(), "Fail returning the dirname of a non-existent theme."),
-          array('theme://bartik', SafeMarkup::format('Get the dirname of %current.', array('%current' => 'theme://current'))),
-          array('theme://bartik', SafeMarkup::format('Get the dirname of a resource in %current.', array('%current' => 'theme://current'))),
-          array('theme://bartik', SafeMarkup::format('Get the dirname of %default.', array('%default' => 'theme://default'))),
-          array('theme://bartik', SafeMarkup::format('Get the dirname of a resource in %default.', array('%default' => 'theme://default'))),
-          array('theme://seven', SafeMarkup::format('Get the dirname of %admin.', array('%admin' => 'theme://admin'))),
-          array('theme://seven', SafeMarkup::format('Get the dirname of a non-existent resource in %admin.', array('%admin' => 'theme://admin'))),
-          array(new \InvalidArgumentException(), "Fail returning the dirname for an uninstalled theme."),
-        ));
-
+        return array_combine($uris, [
+          'theme://seven',
+          'theme://seven',
+          'theme://bartik/color',
+          [new \InvalidArgumentException(), 'Theme fifteen does not exist or is not installed'],
+          'theme://bartik',
+          'theme://bartik',
+          'theme://bartik',
+          'theme://bartik',
+          'theme://seven',
+          'theme://seven',
+          [new \InvalidArgumentException(), 'Theme stark does not exist or is not installed'],
+        ]);
       case 'realpath':
-        $base_path = DRUPAL_ROOT;
-        return array_combine($uris, array(
-          array($base_path . '/core/themes/seven', "Get the realpath of an installed theme."),
-          array($base_path . '/core/themes/seven/style.css', "Get the realpath of a resource located in a theme directory."),
-          array($base_path . '/core/themes/bartik/color/preview.js', "Get the realpath of a resource located in a theme's subdirectory."),
-          array(new \InvalidArgumentException(), "Fail returning the realpath of a non-existent theme."),
-          array($base_path . '/core/themes/bartik', SafeMarkup::format('Get the realpath of %current.', array('%current' => 'theme://current'))),
-          array($base_path . '/core/themes/bartik/logo.png', SafeMarkup::format('Get the realpath of a resource in %current.', array('%current' => 'theme://current'))),
-          array($base_path . '/core/themes/bartik', SafeMarkup::format('Get the realpath of %default.', array('%default' => 'theme://default'))),
-          array($base_path . '/core/themes/bartik/bartik.info.yml', SafeMarkup::format('Get the realpath of a resource in %default.', array('%default' => 'theme://default'))),
-          array($base_path . '/core/themes/seven', SafeMarkup::format('Get the realpath of %admin.', array('%admin' => 'theme://admin'))),
-          array($base_path . '/core/themes/seven/fake.info.yml', SafeMarkup::format('Get the realpath of a non-existent resource in %admin.', array('%admin' => 'theme://admin'))),
-          array(new \InvalidArgumentException(), "Fail returning the realpath for an uninstalled theme."),
-        ));
-
+        return array_combine($uris, [
+          DRUPAL_ROOT . '/core/themes/seven',
+          DRUPAL_ROOT . '/core/themes/seven/style.css',
+          DRUPAL_ROOT . '/core/themes/bartik/color/preview.js',
+          [new \InvalidArgumentException(), 'Theme fifteen does not exist or is not installed'],
+          DRUPAL_ROOT . '/core/themes/bartik',
+          DRUPAL_ROOT . '/core/themes/bartik/logo.png',
+          DRUPAL_ROOT . '/core/themes/bartik',
+          DRUPAL_ROOT . '/core/themes/bartik/bartik.info.yml',
+          DRUPAL_ROOT . '/core/themes/seven',
+          DRUPAL_ROOT . '/core/themes/seven/fake.info.yml',
+          [new \InvalidArgumentException(), 'Theme stark does not exist or is not installed'],
+        ]);
       case 'getExternalUrl':
         $base_url = \Drupal::request()->getUriForPath(base_path());
-        return array_combine($uris, array(
-          array($base_url . 'core/themes/seven', "Lookup theme's external url for a partial URI."),
-          array($base_url . 'core/themes/seven/style.css', "Lookup theme's external url for a resource located in a subdirectory."),
-          array($base_url . 'core/themes/bartik/color/preview.js', "Lookup theme's external url for a resource."),
-          array(new \InvalidArgumentException(), "Fail returning a non-existent theme's external url."),
-          array($base_url . 'core/themes/bartik', SafeMarkup::format('Lookup real external url of %current for a partial URI.', array('%current' => 'theme://current'))),
-          array($base_url . 'core/themes/bartik/logo.png', SafeMarkup::format('Lookup external url of %current for a resource.', array('%current' => 'theme://current'))),
-          array($base_url . 'core/themes/bartik', SafeMarkup::format('Lookup external url of %default for a partial URI.', array('%default' => 'theme://default'))),
-          array($base_url . 'core/themes/bartik/bartik.info.yml', SafeMarkup::format('Lookup external url of %default for a resource.', array('%default' => 'theme://default'))),
-          array($base_url . 'core/themes/seven', SafeMarkup::format('Lookup external url of %admin for a partial URI.', array('%admin' => 'theme://admin'))),
-          array($base_url . 'core/themes/seven/fake.info.yml', SafeMarkup::format('Lookup external url of %admin for a resource.', array('%admin' => 'theme://admin'))),
-          array(new \InvalidArgumentException(), "Fail returning a disabled theme's external url."),
-        ));
+        return array_combine($uris, [
+          $base_url . 'core/themes/seven',
+          $base_url . 'core/themes/seven/style.css',
+          $base_url . 'core/themes/bartik/color/preview.js',
+          [new \InvalidArgumentException(), 'Theme fifteen does not exist or is not installed'],
+          $base_url . 'core/themes/bartik',
+          $base_url . 'core/themes/bartik/logo.png',
+          $base_url . 'core/themes/bartik',
+          $base_url . 'core/themes/bartik/bartik.info.yml',
+          $base_url . 'core/themes/seven',
+          $base_url . 'core/themes/seven/fake.info.yml',
+          [new \InvalidArgumentException(), "Theme stark does not exist or is not installed"],
+        ]);
     }
   }
 
@@ -341,7 +347,7 @@ protected function providerThemeStream($method) {
   /**
    * Helper method to run specific tests on each StreamWrapper method.
    *
-   * @param \Drupal\Core\StreamWrapper\SystemStream $instance
+   * @param \Drupal\Core\StreamWrapper\StreamWrapperInterface $instance
    *   The stream wrapper instance to carry out the test on.
    * @param string $method
    *   The SystemStream method to be tested.
@@ -350,27 +356,40 @@ protected function providerThemeStream($method) {
    *   - The expected result.
    *   - The test result message.
    */
-  private function runTestOnInstanceMethod($instance, $method, array $data) {
+  private function runTestOnInstanceMethod(StreamWrapperInterface $instance, $method, array $data) {
     foreach ($data as $uri => $info) {
       $instance->setUri($uri);
-      if ($info[0] instanceof \InvalidArgumentException) {
+      if (is_array($info)) {
+        $message = sprintf('Exception thrown: \InvalidArgumentException("%s").', $info[1]);
         try {
           $instance->$method();
-          $this->fail($info[1]);
+          $this->fail($message);
         }
         catch (\InvalidArgumentException $e) {
-          $this->pass($info[1]);
+          $this->assertIdentical($e->getMessage(), $info[1], $message);
         }
       }
       else {
         if ($method == 'realpath') {
-          // realpath() returns strings with the OS-specific DIRECTORY_SEPARATOR,
-          // make sure we are testing for that.
-          $info[0] = str_replace('/', DIRECTORY_SEPARATOR, $info[0]);
+          // realpath() returns strings with OS-specific DIRECTORY_SEPARATOR.
+          $info = str_replace('/', DIRECTORY_SEPARATOR, $info);
         }
-        $this->assertEqual($instance->$method(), $info[0], $info[1]);
+        $this->assertEqual($instance->$method(), $info);
       }
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function errorHandler($severity, $message, $file = NULL, $line = NULL) {
+    // When dealing with an unknown module/profile, drupal_get_filename()
+    // triggers an error. We want to mute this error because we catch this as
+    // exception.
+    // @see drupal_get_filename()
+    if ($severity != E_USER_WARNING || strpos($message, 'The following module is missing from the file system: ') !== 0) {
+      parent::errorHandler($severity, $message, $file, $line);
+    }
+  }
+
 }