diff --git a/core/lib/Drupal/Core/StreamWrapper/ProfileStream.php b/core/lib/Drupal/Core/StreamWrapper/ProfileStream.php
index 31a0c0f..bf2cdfc 100644
--- a/core/lib/Drupal/Core/StreamWrapper/ProfileStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/ProfileStream.php
@@ -46,5 +46,4 @@ public function getOwnerName($uri = NULL) {
   public function getDirectoryPath($uri = NULL) {
     return drupal_get_path('profile', $this->getOwnerName($uri));
   }
-
 }
diff --git a/core/lib/Drupal/Core/StreamWrapper/SystemStream.php b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
index cb8267e..289583a 100644
--- a/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
@@ -48,6 +48,20 @@ public function getOwnerName($uri = NULL) {
    * {@inheritdoc}
    */
   public function getTarget($uri = NULL) {
+    $target = $this->extractTarget($uri);
+    return file_exists($this->getDirectoryPath($uri) . '/' . $target) ? $target : NULL;
+  }
+
+  /**
+   * Returns the local target of the resource, regardless of whether it exists.
+   *
+   * @param string $uri
+   *   Optional URI.
+   *
+   * @return bool|string
+   *   A path to the local target.
+   */
+  protected function extractTarget($uri = NULL) {
     // If the owner doesn't exist at all, we don't extract anything.
     if ($this->getOwnerName($uri) === FALSE) {
       return FALSE;
@@ -56,8 +70,7 @@ public function getTarget($uri = NULL) {
     // Remove the preceding owner name including slash from the path.
     $start = strpos($target, '/');
     $target = ($start === FALSE) ? '' : substr($target, $start + 1);
-    // Return the target if it exists in filesystem.
-    return file_exists($this->getDirectoryPath($uri) . '/' . $target) ? $target : FALSE;
+    return $target;
   }
 
   /**
@@ -69,9 +82,8 @@ public function getExternalUrl($uri = NULL) {
       return FALSE;
     }
 
-    $path = str_replace('\\', '/', $this->getTarget($uri));
-    return \Drupal::request()->getBaseUrl() . '/' . $dir . '/' . UrlHelper::encodePath($path);
-
+    $target = $this->extractTarget($uri);
+    $path = $target != '' ? '/' . UrlHelper::encodePath(str_replace('\\', '/', $target)) : '';
+    return \Drupal::request()->getBaseUrl() . '/' . $dir . $path;
   }
-
 }
diff --git a/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php b/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
index 24e925b..29ac6b9 100644
--- a/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
@@ -35,7 +35,7 @@ public function getOwnerName($uri = NULL) {
         return \Drupal::config('system.theme')->get('admin');
       default:
         // Return name only for enabled and admin themes.
-        return drupal_theme_access($name) ? $name : FALSE;
+        return \Drupal::service('access_check.theme')->checkAccess($name) ? $name : FALSE;
     }
   }
 
diff --git a/core/modules/system/src/Tests/File/SystemStreamUnitTest.php b/core/modules/system/src/Tests/File/SystemStreamUnitTest.php
index 9b2a326..45cd6fa 100644
--- a/core/modules/system/src/Tests/File/SystemStreamUnitTest.php
+++ b/core/modules/system/src/Tests/File/SystemStreamUnitTest.php
@@ -2,17 +2,20 @@
 
 /**
  * @file
- * Definition of Drupal\system\Tests\File\StreamWrapperTest.
+ * Contains \Drupal\system\Tests\File\SystemStreamUnitTest.
  */
 
 namespace Drupal\system\Tests\File;
 
-use Drupal\simpletest\DrupalUnitTestBase;
+use Drupal\Core\Site\Settings;
+use Drupal\simpletest\KernelTestBase;
 
 /**
- * Tests stream wrapper functions.
+ * Unit tests for system stream wrapper functions.
+ *
+ * @group system
  */
-class SystemStreamUnitTest extends DrupalUnitTestBase {
+class SystemStreamUnitTest extends KernelTestBase {
 
   /**
    * Modules to enable.
@@ -21,28 +24,29 @@ class SystemStreamUnitTest extends DrupalUnitTestBase {
    */
   public static $modules = array('system', 'file', 'file_test');
 
-  public static function getInfo() {
-    return array(
-      'name' => 'System Stream wrappers',
-      'description' => 'Unit tests system stream wrapper functions.',
-      'group' => 'File API',
-    );
-  }
-
-  function setUp() {
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
     parent::setUp();
     drupal_static_reset('file_get_stream_wrappers');
+    new Settings(Settings::getAll() + array(
+      'install_profile' => 'standard',
+    ));
   }
 
-  function tearDown() {
+  /**
+   * {@inheritdoc}
+   */
+  public function tearDown() {
     parent::tearDown();
   }
 
   /**
    * Test the Module stream wrapper functions.
    */
-  function testModuleStream() {
-    // Generate a module stream wrapper instance
+  public function testModuleStream() {
+    // Generate a module stream wrapper instance.
     $uri1 = 'module://system';
     $uri2 = 'module://system/css/system.admin.css';
     $uri3 = 'module://file_test/file_test.dummy.inc';
@@ -50,6 +54,7 @@ function testModuleStream() {
     $uri5 = 'module://ckeditor/ckeditor.info.yml';
     $uri6 = 'module://foo_bar/foo.bar.js';
     $instance = file_stream_wrapper_get_instance_by_scheme('module');
+    /* @var $instance \Drupal\Core\StreamWrapper\ModuleStream */
 
     // getOwnerName()
     $this->assertEqual($instance->getOwnerName($uri1), 'system', 'Extract module name from a partial URI.');
@@ -81,21 +86,22 @@ function testModuleStream() {
     $this->assertEqual($instance->getExternalUrl($uri2), $base_url . 'core/modules/system/css/system.admin.css', "Lookup module's directory path for a resource located in a subdirectory.");
     $this->assertEqual($instance->getExternalUrl($uri3), $base_url . 'core/modules/file/tests/file_test/file_test.dummy.inc', "Lookup module's directory path for a module located in a subdirectory.");
     $this->assertEqual($instance->getExternalUrl($uri4), $base_url . 'core/modules/file/tests/file_test/includes/file_test.dummy.inc', "Lookup module's directory path even for a non-existing resource, as long as the module exists.");
-    $this->assertFalse($instance->getExternalUrl($uri5), $base_url . "Fail returning a disabled module's directory path");
-    $this->assertFalse($instance->getExternalUrl($uri6), $base_url . "Fail returning a non-existing module's directory path.");
+    $this->assertFalse($instance->getExternalUrl($uri5), "Fail returning a disabled module's directory path");
+    $this->assertFalse($instance->getExternalUrl($uri6), "Fail returning a non-existing module's directory path.");
   }
 
   /**
    * Test the Profile stream wrapper functions.
    */
-  function testProfileStream() {
+  public function testProfileStream() {
     $uri1 = 'profile://minimal';
-    $uri2 = 'profile://minimal/config/block.block.stark.login.yml';
-    $uri3 = 'profile://minimal/config/node.type.article.yml';
+    $uri2 = 'profile://minimal/config/install/block.block.stark_login.yml';
+    $uri3 = 'profile://minimal/config/install/node.type.article.yml';
     $uri4 = 'profile://foo_bar/';
     $uri5 = 'profile://current';
     $uri6 = 'profile://current/standard.info.yml';
     $instance = file_stream_wrapper_get_instance_by_scheme('profile');
+    /* @var $instance \Drupal\Core\StreamWrapper\ProfileStream */
 
     // getOwnerName()
     $this->assertEqual($instance->getOwnerName($uri1), 'minimal', "Extract profile's name from a partial URI.");
@@ -107,7 +113,7 @@ function testProfileStream() {
 
     // getTarget()
     $this->assertEqual($instance->getTarget($uri1), '', 'Return empty target for a partial URI giving only the profile.');
-    $this->assertEqual($instance->getTarget($uri2), 'config/block.block.stark.login.yml', 'Extract target for a resource located in a subdirectory.');
+    $this->assertEqual($instance->getTarget($uri2), 'config/install/block.block.stark_login.yml', 'Extract target for a resource located in a subdirectory.');
     $this->assertFalse($instance->getTarget($uri3), 'Fail returning a target for a non-existing resource.');
     $this->assertFalse($instance->getTarget($uri4), 'Fail returning a target within a non-existing profile.');
     $this->assertEqual($instance->getTarget($uri5), '', format_string('Return empty target for a partial URI giving only %current.', array('%current' => 'profile://current')));
@@ -122,26 +128,27 @@ function testProfileStream() {
     $this->assertEqual($instance->getDirectoryPath($uri6), 'core/profiles/standard', format_string('Lookup real directory path of %current for a resource.', array('%current' => 'profile://current')));
 
     // getExternalUrl()
-    $this->assertEqual($instance->getExternalUrl($uri1), 'core/profiles/minimal', "Lookup profile's directory path for a partial URI.");
-    $this->assertEqual($instance->getExternalUrl($uri2), 'core/profiles/minimal', "Lookup profile's directory path for a resource located in a subdirectory.");
-    $this->assertEqual($instance->getExternalUrl($uri3), 'core/profiles/minimal', "Lookup profile's directory path even for a non-existing resource, as long as the profile exists.");
+    $base_url = \Drupal::request()->getBaseUrl() . '/';
+    $this->assertEqual($instance->getExternalUrl($uri1), $base_url . 'core/profiles/minimal', "Lookup profile's directory path for a partial URI.");
+    $this->assertEqual($instance->getExternalUrl($uri2), $base_url . 'core/profiles/minimal/config/install/block.block.stark_login.yml', "Lookup profile's directory path for a resource located in a subdirectory.");
+    $this->assertEqual($instance->getExternalUrl($uri3), $base_url . 'core/profiles/minimal/config/install/node.type.article.yml', "Lookup profile's directory path even for a non-existing resource, as long as the profile exists.");
     $this->assertFalse($instance->getExternalUrl($uri4), "Fail returning a non-existing profile's directory path.");
-    $this->assertEqual($instance->getExternalUrl($uri5), 'core/profiles/standard', format_string('Lookup real directory path of %current for a partial URI.', array('%current' => 'profile://current')));
-    $this->assertEqual($instance->getExternalUrl($uri6), 'core/profiles/standard', format_string('Lookup real directory path of %current for a resource.', array('%current' => 'profile://current')));
+    $this->assertEqual($instance->getExternalUrl($uri5), $base_url . 'core/profiles/standard', format_string('Lookup real directory path of %current for a partial URI.', array('%current' => 'profile://current')));
+    $this->assertEqual($instance->getExternalUrl($uri6), $base_url . 'core/profiles/standard/standard.info.yml', format_string('Lookup real directory path of %current for a resource.', array('%current' => 'profile://current')));
   }
 
   /**
    * Test the Theme stream wrapper functions.
    */
-  function testThemeStream() {
-    // Disable Bartik theme
-    $system_theme_disabled = config('system.theme.disabled');
-    $this->assertNotIdentical($system_theme_disabled->get('bartik'), '0', format_string('%bartik theme was enabled.', array('%bartik' => 'Bartik')));
+  public function testThemeStream() {
+    // Disable Bartik theme.
+    $system_theme_disabled = \Drupal::config('system.theme.disabled');
+    $this->assertNotIdentical($system_theme_disabled->get('bartik'), 0, format_string('%bartik theme was enabled.', array('%bartik' => 'Bartik')));
     $system_theme_disabled->set('bartik', 0)->save();
-    $this->assertIdentical($system_theme_disabled->get('bartik'), '0', format_string('Now disable %bartik theme.', array('%bartik' => 'Bartik')));
+    $this->assertIdentical($system_theme_disabled->get('bartik'), 0, format_string('Now disable %bartik theme.', array('%bartik' => 'Bartik')));
 
-    // Set admin theme to Seven
-    $system_theme = config('system.theme');
+    // Set admin theme to Seven.
+    $system_theme = \Drupal::config('system.theme');
     $this->assertNull($system_theme->get('admin'), 'No admin theme was set.');
     file_put_contents('admin.theme', print_r($system_theme->get('admin'), TRUE));
     $system_theme->set('admin', 'seven')->save();
@@ -158,6 +165,7 @@ function testThemeStream() {
     $uri9 = 'theme://admin';
     $uri10 = 'theme://admin/stark.info.yml';
     $instance = file_stream_wrapper_get_instance_by_scheme('theme');
+    /* @var $instance \Drupal\Core\StreamWrapper\ThemeStream */
 
     // getOwnerName()
     $this->assertEqual($instance->getOwnerName($uri1), 'seven', "Extract theme's name from a partial URI.");
@@ -196,16 +204,16 @@ function testThemeStream() {
     $this->assertEqual($instance->getDirectoryPath($uri10), 'core/themes/seven', format_string('Lookup real directory path of %admin for a resource.', array('%admin' => 'profile://admin')));
 
     // getExternalUrl()
-    $this->assertEqual($instance->getExternalUrl($uri1), 'core/themes/seven', "Lookup theme's directory path for a partial URI.");
-    $this->assertEqual($instance->getExternalUrl($uri2), 'core/themes/seven', "Lookup theme's directory path for a resource located in a subdirectory.");
-    $this->assertEqual($instance->getExternalUrl($uri3), 'core/themes/bartik', "Lookup theme's directory path for a resource.");
+    $base_url = \Drupal::request()->getBaseUrl() . '/';
+    $this->assertEqual($instance->getExternalUrl($uri1), $base_url . 'core/themes/seven', "Lookup theme's directory path for a partial URI.");
+    $this->assertEqual($instance->getExternalUrl($uri2), $base_url . 'core/themes/seven', "Lookup theme's directory path for a resource located in a subdirectory.");
+    $this->assertEqual($instance->getExternalUrl($uri3), $base_url . 'core/themes/bartik', "Lookup theme's directory path for a resource.");
     $this->assertFalse($instance->getExternalUrl($uri4), "Fail returning a non-existing theme's directory path.");
-    $this->assertEqual($instance->getExternalUrl($uri5), 'core/themes/standard', format_string('Lookup real directory path of %current for a partial URI.', array('%current' => 'profile://current')));
-    $this->assertEqual($instance->getExternalUrl($uri6), 'core/themes/standard', format_string('Lookup real directory path of %current for a resource.', array('%current' => 'profile://current')));
-    $this->assertEqual($instance->getExternalUrl($uri7), 'core/themes/stark', format_string('Lookup real directory path of %default for a partial URI.', array('%default' => 'profile://default')));
-    $this->assertEqual($instance->getExternalUrl($uri8), 'core/themes/stark', format_string('Lookup real directory path of %default for a resource.', array('%default' => 'profile://default')));
-    $this->assertEqual($instance->getExternalUrl($uri9), 'core/themes/seven', format_string('Lookup real directory path of %admin for a partial URI.', array('%admin' => 'profile://admin')));
-    $this->assertEqual($instance->getExternalUrl($uri10), 'core/themes/seven', format_string('Lookup real directory path of %admin for a resource.', array('%admin' => 'profile://admin')));
-
+    $this->assertEqual($instance->getExternalUrl($uri5), $base_url . 'core/themes/standard', format_string('Lookup real directory path of %current for a partial URI.', array('%current' => 'profile://current')));
+    $this->assertEqual($instance->getExternalUrl($uri6), $base_url . 'core/themes/standard', format_string('Lookup real directory path of %current for a resource.', array('%current' => 'profile://current')));
+    $this->assertEqual($instance->getExternalUrl($uri7), $base_url . 'core/themes/stark', format_string('Lookup real directory path of %default for a partial URI.', array('%default' => 'profile://default')));
+    $this->assertEqual($instance->getExternalUrl($uri8), $base_url . 'core/themes/stark', format_string('Lookup real directory path of %default for a resource.', array('%default' => 'profile://default')));
+    $this->assertEqual($instance->getExternalUrl($uri9), $base_url . 'core/themes/seven', format_string('Lookup real directory path of %admin for a partial URI.', array('%admin' => 'profile://admin')));
+    $this->assertEqual($instance->getExternalUrl($uri10), $base_url . 'core/themes/seven', format_string('Lookup real directory path of %admin for a resource.', array('%admin' => 'profile://admin')));
   }
 }