diff --git a/core/core.services.yml b/core/core.services.yml
index afccb31..42cb057 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1242,6 +1242,34 @@ services:
     class: Drupal\Core\StreamWrapper\TemporaryStream
     tags:
       - { name: stream_wrapper, scheme: temporary }
+  stream_wrapper.module:
+    class: Drupal\Core\StreamWrapper\ModuleStream
+    tags:
+      - { name: stream_wrapper, scheme: module }
+  stream_wrapper.theme:
+    class: Drupal\Core\StreamWrapper\ThemeStream
+    tags:
+      - { name: stream_wrapper, scheme: theme }
+  stream_wrapper.active_theme:
+    class: Drupal\Core\StreamWrapper\ActiveThemeStream
+    tags:
+      - { name: stream_wrapper, scheme: active-theme }
+  stream_wrapper.admin_theme:
+    class: Drupal\Core\StreamWrapper\AdminThemeStream
+    tags:
+      - { name: stream_wrapper, scheme: admin-theme }
+  stream_wrapper.default_theme:
+    class: Drupal\Core\StreamWrapper\DefaultThemeStream
+    tags:
+      - { name: stream_wrapper, scheme: default-theme }
+  stream_wrapper.profile:
+    class: Drupal\Core\StreamWrapper\ProfileStream
+    tags:
+      - { name: stream_wrapper, scheme: profile }
+  stream_wrapper.installed_profile:
+    class: Drupal\Core\StreamWrapper\InstalledProfileStream
+    tags:
+      - { name: stream_wrapper, scheme: installed-profile }
   kernel_destruct_subscriber:
     class: Drupal\Core\EventSubscriber\KernelDestructionSubscriber
     tags:
diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index ce872d4..0240643 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -240,14 +240,18 @@ function drupal_get_filename($type, $name, $filename = NULL) {
 /**
  * Returns the path to a system item (module, theme, etc.).
  *
- * @param $type
+ * This function should only be used when including a file containing PHP code;
+ * the 'module://', 'profile://' and 'theme://' stream wrappers should be used
+ * for other use cases.
+ *
+ * @param string $type
  *   The type of the item; one of 'core', 'profile', 'module', 'theme', or
  *   'theme_engine'.
  * @param $name
  *   The name of the item for which the path is requested. Ignored for
  *   $type 'core'.
  *
- * @return
+ * @return string
  *   The path to the requested item or an empty string if the item is not found.
  */
 function drupal_get_path($type, $name) {
diff --git a/core/lib/Drupal/Core/StreamWrapper/ActiveThemeStream.php b/core/lib/Drupal/Core/StreamWrapper/ActiveThemeStream.php
new file mode 100644
index 0000000..5d2237c
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/ActiveThemeStream.php
@@ -0,0 +1,59 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\ActiveThemeStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the read-only active-theme:// stream wrapper for the active theme.
+ */
+class ActiveThemeStream extends PseudoThemeStreamBase {
+
+  /**
+   * The theme negotiator service.
+   *
+   * @var \Drupal\Core\Theme\ThemeNegotiatorInterface
+   */
+  protected $themeNegotiator;
+
+  /**
+   * The route matching service.
+   *
+   * @var \Drupal\Core\Routing\RouteMatchInterface
+   */
+  protected $routeMatch;
+
+  /**
+   * Constructs a new ActiveThemeStream object.
+   */
+  public function __construct() {
+    parent::__construct();
+    $this->themeNegotiator = \Drupal::service('theme.negotiator');
+    $this->routeMatch = \Drupal::service('current_route_match');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getOwnerName() {
+    return $this->themeNegotiator->determineActiveTheme($this->routeMatch);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Active theme files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Local active theme files.');
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/AdminThemeStream.php b/core/lib/Drupal/Core/StreamWrapper/AdminThemeStream.php
new file mode 100644
index 0000000..a632c17
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/AdminThemeStream.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\AdminThemeStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the read-only admin-theme:// stream wrapper for the active theme.
+ */
+class AdminThemeStream extends PseudoThemeStreamBase {
+
+  /**
+   * The config factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * Constructs a new ActiveThemeStream object.
+   */
+  public function __construct() {
+    parent::__construct();
+    $this->configFactory = \Drupal::configFactory();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getOwnerName() {
+    return $this->configFactory->get('system.theme')->get('admin');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Admin theme files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Local admin theme files.');
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/DefaultThemeStream.php b/core/lib/Drupal/Core/StreamWrapper/DefaultThemeStream.php
new file mode 100644
index 0000000..2189f21
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/DefaultThemeStream.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\DefaultThemeStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the read-only default-theme:// stream wrapper for the active theme.
+ */
+class DefaultThemeStream extends PseudoThemeStreamBase {
+
+  /**
+   * The theme handler service.
+   *
+   * @var \Drupal\Core\Extension\ThemeHandlerInterface
+   */
+  protected $themeHandler;
+
+  /**
+   * Constructs a new ActiveThemeStream object.
+   */
+  public function __construct() {
+    parent::__construct();
+    $this->themeHandler = \Drupal::service('theme_handler');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getOwnerName() {
+    return $this->themeHandler->getDefault();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Default theme files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Local default theme files.');
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/InstalledProfileStream.php b/core/lib/Drupal/Core/StreamWrapper/InstalledProfileStream.php
new file mode 100644
index 0000000..0302c38
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/InstalledProfileStream.php
@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\InstalledProfileStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the read-only installed-profile:// stream wrapper for the installed
+ * profile files.
+ */
+class InstalledProfileStream extends PseudoSystemStreamBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getOwnerName() {
+    return drupal_get_profile();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Current profile files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Local current profile files.');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getDirectoryPath() {
+    return dirname(drupal_get_filename('profile', $this->getOwnerName()));
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/LocalStream.php b/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
index 82f4427..db51eda 100644
--- a/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/LocalStream.php
@@ -57,7 +57,7 @@ public static function getType() {
    * @return string
    *   String specifying the path.
    */
-  abstract function getDirectoryPath();
+  protected abstract function getDirectoryPath();
 
   /**
    * {@inheritdoc}
@@ -85,25 +85,31 @@ function getUri() {
    * @param string $uri
    *   Optional URI.
    *
-   * @return string|bool
-   *   Returns a string representing a location suitable for writing of a file,
-   *   or FALSE if unable to write to the file such as with read-only streams.
+   * @return string
+   *   Returns a string representing a location suitable for writing of a file.
+   *
+   * @throws \InvalidArgumentException
+   *   If a malformed $uri parameter is passed in.
    */
   protected function getTarget($uri = NULL) {
     if (!isset($uri)) {
       $uri = $this->uri;
     }
 
-    list(, $target) = explode('://', $uri, 2);
+    $uri_parts = explode('://', $uri, 2);
+    if (count($uri_parts) === 1) {
+      // The delimiter ('://') was not found in $uri, malformed $uri passed.
+      throw new \InvalidArgumentException(sprintf('Malformed uri parameter passed: %s', $uri));
+    }
 
-    // Remove erroneous leading or trailing, forward-slashes and backslashes.
-    return trim($target, '\/');
+    // Remove erroneous leading or trailing forward-slashes and backslashes.
+    return trim($uri_parts[1], '\/');
   }
 
   /**
    * {@inheritdoc}
    */
-  function realpath() {
+  public function realpath() {
     return $this->getLocalPath();
   }
 
diff --git a/core/lib/Drupal/Core/StreamWrapper/ModuleStream.php b/core/lib/Drupal/Core/StreamWrapper/ModuleStream.php
new file mode 100644
index 0000000..3424c56
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/ModuleStream.php
@@ -0,0 +1,68 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\ModuleStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * Defines the read-only module:// stream wrapper for module files.
+ */
+class ModuleStream extends SystemStream {
+
+  /**
+   * Wraps the ModuleHandler service.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  protected $moduleHandler;
+
+  /**
+   * Constructs a ModuleStream wrapper object.
+   */
+  public function __construct() {
+    parent::__construct();
+    $this->moduleHandler = \Drupal::moduleHandler();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getOwnerName() {
+    $name = parent::getOwnerName();
+    if ($this->moduleHandler->moduleExists($name)) {
+      return $name;
+    }
+    else {
+      // The module does not exist or is not installed.
+      throw new \InvalidArgumentException(sprintf('Module %s does not exist or is not installed', $name));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getDirectoryPath() {
+    return $this->moduleHandler->getModule($this->getOwnerName())->getPath();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Module files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Local module files.');
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/ProfileStream.php b/core/lib/Drupal/Core/StreamWrapper/ProfileStream.php
new file mode 100644
index 0000000..539ffc5
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/ProfileStream.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\ProfileStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the read-only profile:// stream wrapper for profile files.
+ */
+class ProfileStream extends SystemStream {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getOwnerName() {
+    $name = parent::getOwnerName();
+
+    if (!is_null(drupal_get_filename('profile', $name))) {
+      return $name;
+    }
+    else {
+      // The profile does not exist.
+      throw new \InvalidArgumentException(sprintf('Profile %s does not exist', $name));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getDirectoryPath() {
+    return dirname(drupal_get_filename('profile', $this->getOwnerName()));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Profile files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Local profile files.');
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/PseudoSystemStreamBase.php b/core/lib/Drupal/Core/StreamWrapper/PseudoSystemStreamBase.php
new file mode 100644
index 0000000..2ad51be
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/PseudoSystemStreamBase.php
@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\PseudoSystemStreamBase.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the base class for read-only installed-profile://, active-theme://,
+ * default-theme:// and admin-theme:// stream wrappers.
+ */
+abstract class PseudoSystemStreamBase extends SystemStream {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dirname($uri = NULL) {
+    if (!isset($uri)) {
+      $uri = $this->uri;
+    }
+
+    list($scheme) = explode('://', $uri, 2);
+    $target = $this->getTarget($uri);
+
+    $dirname = dirname($target);
+
+    if ($dirname === '.' || $dirname === '\\') {
+      $dirname = '';
+    }
+
+    return "$scheme://" . trim($dirname, '/');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getTarget($uri = NULL) {
+    if (!isset($uri)) {
+      $uri = $this->uri;
+    }
+
+    $uri_parts = explode('://', $uri, 2);
+    if (count($uri_parts) === 1) {
+      // The delimiter ('://') was not found in $uri, malformed $uri passed.
+      throw new \InvalidArgumentException(sprintf('Malformed uri parameter passed: %s', $uri));
+    }
+
+    $target = trim($uri_parts[1], '\/');
+
+    return !empty($target) ? "/$target" : '';
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/PseudoThemeStreamBase.php b/core/lib/Drupal/Core/StreamWrapper/PseudoThemeStreamBase.php
new file mode 100644
index 0000000..697784c
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/PseudoThemeStreamBase.php
@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\PseudoThemeStreamBase.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the base class for read-only 'active-theme://', 'default-theme://'
+ * and 'admin-theme://' theme stream wrappers.
+ */
+abstract class PseudoThemeStreamBase extends PseudoSystemStreamBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getDirectoryPath() {
+    return dirname(drupal_get_filename('theme', $this->getOwnerName()));
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
index f13cfb8..2bf1502 100644
--- a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
+++ b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
@@ -182,7 +182,7 @@ public function realpath();
    *   An optional URI.
    *
    * @return string
-   *   A string containing the directory name, or FALSE if not applicable.
+   *   A string containing the directory name.
    *
    * @see drupal_dirname()
    */
diff --git a/core/lib/Drupal/Core/StreamWrapper/SystemStream.php b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
new file mode 100644
index 0000000..bf064d2
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/SystemStream.php
@@ -0,0 +1,101 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\SystemStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines a base stream wrapper implementation.
+ *
+ * SystemStream is a read-only Drupal stream wrapper base class for system files
+ * located in modules, themes and profiles.
+ */
+abstract class SystemStream extends LocalReadOnlyStream {
+  /**
+   * The request object.
+   *
+   * @var \Symfony\Component\HttpFoundation\Request
+   */
+  protected $request;
+
+  /**
+   * Constructs a new system stream.
+   */
+  public function __construct() {
+    $this->request = \Drupal::service('request_stack')->getCurrentRequest();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getType() {
+    return StreamWrapperInterface::LOCAL | StreamWrapperInterface::READ;
+  }
+
+  /**
+   * Gets the module, theme, or profile name of the current URI.
+   *
+   * This will return the name of the module, theme or profile e.g.
+   * @code SystemStream::getOwnerName('module://foo') @endcode and @code
+   * SystemStream::getOwnerName('module://foo/')@endcode will both return @code
+   * 'foo'@endcode
+   *
+   * @return string
+   *   The extension name.
+   *
+   * @throws \InvalidArgumentException
+   */
+  protected function getOwnerName() {
+    $uri_parts = explode('://', $this->uri, 2);
+    if (count($uri_parts) === 1) {
+      // The delimiter ('://') was not found in $uri, malformed $uri passed.
+      throw new \InvalidArgumentException(sprintf('Malformed uri parameter passed: %s', $this->uri));
+    }
+
+    // Remove the trailing filename from the path.
+    $length = strpos($uri_parts[1], '/');
+    return ($length === FALSE) ? $uri_parts[1] : substr($uri_parts[1], 0, $length);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getTarget($uri = NULL) {
+    return rtrim(strstr(parent::getTarget($uri), '/') ?: '', '/');
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * @throws \InvalidArgumentException
+   */
+  public function getExternalUrl() {
+    $dir = $this->getDirectoryPath();
+    if (empty($dir)) {
+      throw new \InvalidArgumentException(sprintf('Extension directory for %s does not exist.', $this->uri));
+    }
+    return $this->request->getUriForPath(base_path() . $dir . $this->getTarget());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function dirname($uri = NULL) {
+    if (!isset($uri)) {
+      $uri = $this->uri;
+    }
+    list($scheme) = explode('://', $uri, 2);
+    $target = $this->getTarget($uri);
+    $dirname = dirname($target);
+
+    if ($dirname === '.' || $dirname === '\\') {
+      $dirname = '';
+    }
+
+    return rtrim($scheme . '://' . $this->getOwnerName() . $dirname, '/');
+  }
+
+}
diff --git a/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php b/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
new file mode 100644
index 0000000..d39015f
--- /dev/null
+++ b/core/lib/Drupal/Core/StreamWrapper/ThemeStream.php
@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\StreamWrapper\ThemeStream.
+ */
+
+namespace Drupal\Core\StreamWrapper;
+
+/**
+ * Defines the read-only theme:// stream wrapper for theme files.
+ */
+class ThemeStream extends SystemStream {
+
+  /**
+   * The theme handler service.
+   *
+   * @var \Drupal\Core\Extension\ThemeHandlerInterface
+   */
+  protected $themeHandler;
+
+  /**
+   * Constructs a new ThemeStream object.
+   */
+  public function __construct() {
+    parent::__construct();
+    $this->themeHandler = \Drupal::service('theme_handler');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getOwnerName() {
+    $name = parent::getOwnerName();
+
+    // Return name only for installed themes.
+    if ($this->themeHandler->themeExists($name)) {
+      return $name;
+    }
+    else {
+      // The theme does not exist or is not installed.
+      throw new \InvalidArgumentException(sprintf('Theme %s does not exist or is not installed', $name));
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getDirectoryPath() {
+    return $this->themeHandler->getTheme($this->getOwnerName())->getPath();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName() {
+    return t('Theme files');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return t('Local theme files.');
+  }
+
+}
diff --git a/core/modules/color/tests/modules/color_test/color_test.module b/core/modules/color/tests/modules/color_test/color_test.module
index 603906e..b89e5e4 100644
--- a/core/modules/color/tests/modules/color_test/color_test.module
+++ b/core/modules/color/tests/modules/color_test/color_test.module
@@ -9,6 +9,6 @@
  * Implements hook_system_theme_info().
  */
 function color_test_system_theme_info() {
-  $themes['color_test_theme'] = drupal_get_path('module', 'color_test') . '/themes/color_test_theme/color_test_theme.info.yml';
+  $themes['color_test_theme'] = 'module://color_test/themes/color_test_theme/color_test_theme.info.yml';
   return $themes;
 }
diff --git a/core/modules/file/tests/file_test/file_test.dummy.inc b/core/modules/file/tests/file_test/file_test.dummy.inc
new file mode 100644
index 0000000..a09fd2e
--- /dev/null
+++ b/core/modules/file/tests/file_test/file_test.dummy.inc
@@ -0,0 +1 @@
+Dummy file used by SystemStreamTest.php.
diff --git a/core/modules/search/src/Tests/SearchSimplifyTest.php b/core/modules/search/src/Tests/SearchSimplifyTest.php
index 82363fd..6780ba0 100644
--- a/core/modules/search/src/Tests/SearchSimplifyTest.php
+++ b/core/modules/search/src/Tests/SearchSimplifyTest.php
@@ -25,7 +25,7 @@ function testSearchSimplifyUnicode() {
     // their own lines).  So the even-numbered lines should simplify to nothing,
     // and the odd-numbered lines we need to split into shorter chunks and
     // verify that simplification doesn't lose any characters.
-    $input = file_get_contents(\Drupal::root() . '/core/modules/search/tests/UnicodeTest.txt');
+    $input = file_get_contents('module://search/tests/UnicodeTest.txt');
     $basestrings = explode(chr(10), $input);
     $strings = array();
     foreach ($basestrings as $key => $string) {
diff --git a/core/modules/system/src/Tests/File/SystemStreamTest.php b/core/modules/system/src/Tests/File/SystemStreamTest.php
new file mode 100644
index 0000000..4bb8b0e
--- /dev/null
+++ b/core/modules/system/src/Tests/File/SystemStreamTest.php
@@ -0,0 +1,483 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\File\SystemStreamTest.
+ */
+
+namespace Drupal\system\Tests\File;
+
+use Drupal\Component\Utility\SafeMarkup;
+use Drupal\Core\Site\Settings;
+use Drupal\Core\StreamWrapper\StreamWrapperInterface;
+use Drupal\Core\Theme\ActiveTheme;
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Tests system stream wrapper functions.
+ *
+ * @group system
+ */
+class SystemStreamTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['system', 'file', 'file_test'];
+
+  /**
+   * The stream wrapper manager service.
+   *
+   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
+   */
+  protected $streamWrapperManager;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+
+    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() +  ['install_profile' => 'minimal']);
+  }
+
+  /**
+   * Test Invalid stream uri.
+   */
+  public function testInvalidStreamUriException() {
+    $bad_uris = [
+      'invalid/uri',
+      'invalid_uri',
+      'module/invalid/uri',
+      'module/invalid_uri',
+      'module:invalid_uri',
+      'module::/invalid/uri',
+      'module::/invalid_uri',
+      'module//:invalid/uri',
+      'module//invalid_uri',
+      'module//invalid/uri',
+    ];
+
+    $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.', ['%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.', ['%uri' => $bad_uri]));
+        }
+        else {
+          throw new \InvalidArgumentException($e);
+        }
+      }
+    }
+  }
+
+  /**
+   * Test the Module stream wrapper functions.
+   */
+  public function testModuleStream() {
+    // Generate a module stream wrapper instance.
+    $instance = $this->streamWrapperManager->getViaScheme('module');
+
+    // Test dirname().
+    $data = $this->moduleStreamTestCasesProvider('dirname');
+    $this->runTestOnInstanceMethod($instance, 'dirname', $data);
+
+    // Test realpath().
+    $data = $this->moduleStreamTestCasesProvider('realpath');
+    $this->runTestOnInstanceMethod($instance, 'realpath', $data);
+
+    // Test getExternalUrl().
+    $data = $this->moduleStreamTestCasesProvider('getExternalUrl');
+    $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
+  }
+
+  /**
+   * Provides test cases for testModuleStream().
+   *
+   * @param string $method
+   *   The method to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
+   */
+  protected function moduleStreamTestCasesProvider($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($uris, [
+          'module://system',
+          'module://system/css',
+          'module://file_test',
+          'module://file_test/src',
+          new \InvalidArgumentException('Module ckeditor does not exist or is not installed'),
+          new \InvalidArgumentException('Module foo_bar does not exist or is not installed'),
+        ]);
+      case 'realpath':
+        return array_combine($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, [
+          $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'),
+        ]);
+    }
+  }
+
+  /**
+   * Test the Profile stream wrapper functions.
+   */
+  public function testProfileStream() {
+    // Generate a profile stream wrapper instance.
+    $instance = $this->streamWrapperManager->getViaScheme('profile');
+
+    // Test dirname().
+    $data = $this->profileStreamTestCasesProvider('dirname');
+    $this->runTestOnInstanceMethod($instance, 'dirname', $data);
+
+    // Test realpath().
+    $data = $this->profileStreamTestCasesProvider('realpath');
+    $this->runTestOnInstanceMethod($instance, 'realpath', $data);
+
+    // Test getExternalUrl().
+    $data = $this->profileStreamTestCasesProvider('getExternalUrl');
+    $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
+  }
+
+  /**
+   * Provides test cases for testProfileStream().
+   *
+   * @param string $method
+   *   The method to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
+   */
+  protected function profileStreamTestCasesProvider($method) {
+    $uris = [
+      'profile://minimal',
+      'profile://minimal/config/install/block.block.stark_login.yml',
+      'profile://minimal/config/install/node.type.article.yml',
+      'profile://foo_bar/',
+    ];
+
+    switch ($method) {
+      case 'dirname':
+        return array_combine($uris, [
+          'profile://minimal',
+          'profile://minimal/config/install',
+          'profile://minimal/config/install',
+          new \InvalidArgumentException('Profile foo_bar does not exist'),
+        ]);
+      case 'realpath':
+        return array_combine($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'),
+        ]);
+      case 'getExternalUrl':
+        $base_url = \Drupal::request()->getUriForPath(base_path());
+        return array_combine($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'),
+        ]);
+    }
+  }
+
+  /**
+   * Test the installed profile stream wrapper functions.
+   */
+  public function testInstalledProfileStream() {
+    // Generate a profile stream wrapper instance.
+    $instance = $this->streamWrapperManager->getViaScheme('installed-profile');
+
+    // Test dirname().
+    $data = $this->installedProfileStreamTestCasesProvider('dirname');
+    $this->runTestOnInstanceMethod($instance, 'dirname', $data);
+
+    // Test realpath().
+    $data = $this->installedProfileStreamTestCasesProvider('realpath');
+    $this->runTestOnInstanceMethod($instance, 'realpath', $data);
+
+    // Test getExternalUrl().
+    $data = $this->installedProfileStreamTestCasesProvider('getExternalUrl');
+    $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
+  }
+
+  /**
+   * Provides test cases for testProfileStream().
+   *
+   * @param string $method
+   *   The method to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
+   */
+  protected function installedProfileStreamTestCasesProvider($method) {
+    $uris = [
+      'installed-profile://',
+      'installed-profile://config/install/block.block.stark_login.yml',
+      'installed-profile://config/install/node.type.article.yml',
+      'installed-profile://minimal.info.yml',
+    ];
+
+    switch ($method) {
+      case 'dirname':
+        return array_combine($uris, [
+          'installed-profile://',
+          'installed-profile://config/install',
+          'installed-profile://config/install',
+          'installed-profile://',
+        ]);
+      case 'realpath':
+        return array_combine($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',
+          DRUPAL_ROOT . '/core/profiles/minimal/minimal.info.yml',
+        ]);
+      case 'getExternalUrl':
+        $base_url = \Drupal::request()->getUriForPath(base_path());
+        return array_combine($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',
+          $base_url . 'core/profiles/minimal/minimal.info.yml',
+        ]);
+    }
+  }
+
+  /**
+   * Test the Theme stream wrapper functions.
+   */
+  public function testThemeStream() {
+    /** @var \Drupal\Core\Extension\ThemeInstallerInterface $theme_installer */
+    $theme_installer = $this->container->get('theme_installer');
+    // Install Bartik and Seven themes.
+    $theme_installer->install(['bartik', 'seven']);
+
+    // Generate a theme stream wrapper instance.
+    $instance = $this->streamWrapperManager->getViaScheme('theme');
+
+    // Test dirname().
+    $data = $this->themeStreamTestCasesProvider('dirname');
+    $this->runTestOnInstanceMethod($instance, 'dirname', $data);
+
+    // Test realpath().
+    $data = $this->themeStreamTestCasesProvider('realpath');
+    $this->runTestOnInstanceMethod($instance, 'realpath', $data);
+
+    // Test getExternalUrl().
+    $data = $this->themeStreamTestCasesProvider('getExternalUrl');
+    $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
+  }
+
+  /**
+   * Provides test cases for testThemeStream().
+   *
+   * @param string $method
+   *   The method to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
+   */
+  protected function themeStreamTestCasesProvider($method) {
+    $uris = [
+      'theme://seven',
+      'theme://seven/style.css',
+      'theme://bartik/color/preview.js',
+      'theme://fifteen/screenshot.png',
+      'theme://stark/stark.info.yml',
+    ];
+
+    switch ($method) {
+      case 'dirname':
+        return array_combine($uris, [
+          'theme://seven',
+          'theme://seven',
+          'theme://bartik/color',
+          new \InvalidArgumentException('Theme fifteen does not exist or is not installed'),
+          new \InvalidArgumentException('Theme stark does not exist or is not installed'),
+        ]);
+      case 'realpath':
+        return array_combine($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'),
+          new \InvalidArgumentException('Theme stark does not exist or is not installed'),
+        ]);
+      case 'getExternalUrl':
+        $base_url = \Drupal::request()->getUriForPath(base_path());
+        return array_combine($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'),
+          new \InvalidArgumentException('Theme stark does not exist or is not installed'),
+        ]);
+    }
+  }
+
+  /**
+   * Test the pseudo theme stream wrapper functions.
+   */
+  public function testPseudoThemeStreams() {
+    /** @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');
+
+    // Install Bartik theme.
+    $theme_installer->install(['bartik']);
+    // Set default and admin theme to Bartik.
+    $config_factory->getEditable('system.theme')
+      ->set('default', 'bartik')
+      ->set('admin', 'bartik')
+      ->save();
+
+    foreach (['active', 'default', 'admin'] as $scheme) {
+      $scheme .= '-theme';
+
+      // Generate a theme stream wrapper instance.
+      $instance = $this->streamWrapperManager->getViaScheme($scheme);
+
+      // Test dirname().
+      $data = $this->pseudoThemeStreamTestCasesProvider('dirname', $scheme);
+      $this->runTestOnInstanceMethod($instance, 'dirname', $data);
+
+      // Test realpath().
+      $data = $this->pseudoThemeStreamTestCasesProvider('realpath', $scheme);
+      $this->runTestOnInstanceMethod($instance, 'realpath', $data);
+
+      // Test getExternalUrl().
+      $data = $this->pseudoThemeStreamTestCasesProvider('getExternalUrl', $scheme);
+      $this->runTestOnInstanceMethod($instance, 'getExternalUrl', $data);
+    }
+  }
+
+  /**
+   * Provides test cases for testPseudoThemeStreams().
+   *
+   * @param string $method
+   *   The method to be tested.
+   * @param string $scheme
+   *   The scheme to be tested.
+   *
+   * @return array
+   *   Associative array with test cases as values, keyed by uri.
+   */
+  protected function pseudoThemeStreamTestCasesProvider($method, $scheme) {
+    $uris = [
+      "$scheme://",
+      "$scheme://logo.png",
+      "$scheme://color/preview.js",
+    ];
+
+    switch ($method) {
+      case 'dirname':
+        return array_combine($uris, [
+          "$scheme://",
+          "$scheme://",
+          "$scheme://color",
+        ]);
+      case 'realpath':
+        return array_combine($uris, [
+          DRUPAL_ROOT . '/core/themes/bartik',
+          DRUPAL_ROOT . '/core/themes/bartik/logo.png',
+          DRUPAL_ROOT . '/core/themes/bartik/color/preview.js',
+        ]);
+      case 'getExternalUrl':
+        $base_url = \Drupal::request()->getUriForPath(base_path());
+        return array_combine($uris, [
+          $base_url . 'core/themes/bartik',
+          $base_url . 'core/themes/bartik/logo.png',
+          $base_url . 'core/themes/bartik/color/preview.js',
+        ]);
+    }
+  }
+
+  /**
+   * Helper method to run specific tests on each StreamWrapper method.
+   *
+   * @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.
+   * @param array $data
+   *   An array of data to be used for the test, containing the following info:
+   *   - The expected result.
+   *   - The test result message.
+   */
+  private function runTestOnInstanceMethod(StreamWrapperInterface $instance, $method, array $data) {
+    foreach ($data as $uri => $case) {
+      $instance->setUri($uri);
+      if ($case instanceof \InvalidArgumentException) {
+        /** @var \InvalidArgumentException $case */
+        $message = sprintf('Exception thrown: \InvalidArgumentException("%s").', $case->getMessage());
+        try {
+          $instance->$method();
+          $this->fail($message);
+        }
+        catch (\InvalidArgumentException $e) {
+          $this->assertIdentical($e->getMessage(), $case->getMessage(), $message);
+        }
+      }
+      elseif (is_string($case)) {
+        $this->assertEqual($instance->$method(), $case);
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function errorHandler($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);
+    }
+  }
+
+}