diff --git a/core/includes/file.inc b/core/includes/file.inc
index 9319755..f713d1f 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -7,6 +7,7 @@
 
 use Drupal\Core\StreamWrapper\LocalStream;
 use Drupal\Component\PhpStorage\MTimeProtectedFastFileStorage;
+use Drupal\Core\StreamWrapper\PublicStream;
 
 /**
  * Stream wrapper bit flags that are the basis for composite types.
@@ -385,7 +386,7 @@ function file_stream_wrapper_get_instance_by_uri($uri) {
  * @param $scheme
  *   If the stream was "public://target", "public" would be the scheme.
  *
- * @return
+ * @return \Drupal\Core\StreamWrapper\StreamWrapperInterface
  *   Returns a new stream wrapper object appropriate for the given $scheme.
  *   For example, for the public scheme a stream wrapper object
  *   (Drupal\Core\StreamWrapper\PublicStream).
@@ -1614,7 +1615,7 @@ function file_directory_temp() {
 
     if (empty($temporary_directory)) {
       // If no directory has been found default to 'files/tmp'.
-      $temporary_directory = variable_get('file_public_path', conf_path() . '/files') . '/tmp';
+      $temporary_directory = PublicStream::basePath() . '/tmp';
 
       // Windows accepts paths with either slash (/) or backslash (\), but will
       // not accept a path which contains both a slash and a backslash. Since
diff --git a/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php b/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php
index c82cfcd..15a7eb2 100644
--- a/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php
+++ b/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\Component\PhpStorage;
+use Drupal\Core\StreamWrapper\PublicStream;
 
 /**
  * Creates a php storage object
@@ -49,8 +50,7 @@ static function get($name) {
       $configuration['bin'] = $name;
     }
     if (!isset($configuration['directory'])) {
-      $path = isset($conf['file_public_path']) ? $conf['file_public_path'] : conf_path() . '/files';
-      $configuration['directory'] = DRUPAL_ROOT . "/$path/php";
+      $configuration['directory'] = DRUPAL_ROOT . '/' . PublicStream::basePath() . '/php';
     }
     return new $class($configuration);
   }
diff --git a/core/lib/Drupal/Core/StreamWrapper/PublicStream.php b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
index 207b77a..94f5514 100644
--- a/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
@@ -16,20 +16,36 @@
 class PublicStream extends LocalStream {
 
   /**
-   * Implements Drupal\Core\StreamWrapper\LocalStream::getDirectoryPath()
+   * {@inheritdoc}
    */
   public function getDirectoryPath() {
-    return variable_get('file_public_path', conf_path() . '/files');
+    return static::basePath();
   }
 
   /**
-   * Implements Drupal\Core\StreamWrapper\StreamWrapperInterface::getExternalUrl().
-   *
-   * @return string
-   *   Returns the HTML URI of a public file.
+   * {@inheritdoc}
    */
-  function getExternalUrl() {
+  public function getExternalUrl() {
     $path = str_replace('\\', '/', $this->getTarget());
     return $GLOBALS['base_url'] . '/' . self::getDirectoryPath() . '/' . drupal_encode_path($path);
   }
+
+  /**
+   * Returns the base path for public://.
+   *
+   * @return string
+   *   The base path for public:// typically sites/default/files.
+   */
+  public static function basePath() {
+    $base_path = settings()->get('file_public_path', conf_path() . '/files');
+    if ($test_prefix = drupal_valid_test_ua()) {
+      // Append the testing suffix unless already given.
+      // @see Drupal\simpletest\WebTestBase::setUp()
+      if (strpos($base_path, '/simpletest/' . substr($test_prefix, 10)) === FALSE) {
+        return $base_path . '/simpletest/' . substr($test_prefix, 10);
+      }
+    }
+    return $base_path;
+  }
+
 }
diff --git a/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php b/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
index 548eb8e..bea3e82 100644
--- a/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
+++ b/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\filter\Tests;
 
+use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -75,7 +76,7 @@ function setUp() {
   function testImageSource() {
     global $base_url;
 
-    $public_files_path = variable_get('file_public_path', conf_path() . '/files');
+    $public_files_path = PublicStream::basePath();
 
     $http_base_url = preg_replace('/^https?/', 'http', $base_url);
     $https_base_url = preg_replace('/^https?/', 'https', $base_url);
diff --git a/core/modules/image/image.module b/core/modules/image/image.module
index 03b8c95..fa03dcd 100644
--- a/core/modules/image/image.module
+++ b/core/modules/image/image.module
@@ -227,25 +227,6 @@ function image_permission() {
 }
 
 /**
- * Implements hook_form_FORM_ID_alter().
- */
-function image_form_system_file_system_settings_alter(&$form, &$form_state) {
-  $form['#submit'][] = 'image_system_file_system_settings_submit';
-}
-
-/**
- * Form submission handler for system_file_system_settings().
- *
- * Adds a menu rebuild after the public file path has been changed, so that the
- * menu router item depending on that file path will be regenerated.
- */
-function image_system_file_system_settings_submit($form, &$form_state) {
-  if ($form['file_public_path']['#default_value'] !== $form_state['values']['file_public_path']) {
-    Drupal::state()->set('menu_rebuild_needed', TRUE);
-  }
-}
-
-/**
  * Implements hook_file_download().
  *
  * Control the access to files underneath the styles directory.
diff --git a/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateBase.php b/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateBase.php
index 46d082e..3e185df 100644
--- a/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateBase.php
+++ b/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateBase.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\locale\Tests;
 
+use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\simpletest\WebTestBase;
 use Drupal\Component\Utility\String;
 
@@ -172,7 +173,7 @@ protected function setTranslationFiles() {
     \Drupal::state()->set('locale.test_projects_alter', TRUE);
 
     // Setup the environment.
-    $public_path = variable_get('file_public_path', conf_path() . '/files');
+    $public_path = PublicStream::basePath();
     $this->setTranslationsDirectory($public_path . '/local');
     $config->set('translation.default_filename', '%project-%version.%language._po')->save();
 
diff --git a/core/modules/locale/tests/modules/locale_test/locale_test.module b/core/modules/locale/tests/modules/locale_test/locale_test.module
index 1ba430c..973a27b 100644
--- a/core/modules/locale/tests/modules/locale_test/locale_test.module
+++ b/core/modules/locale/tests/modules/locale_test/locale_test.module
@@ -4,6 +4,7 @@
  * @file
  * Simulate a custom module with a local po file.
  */
+use Drupal\Core\StreamWrapper\PublicStream;
 
 /**
  * Implements hook_system_info_alter().
@@ -42,7 +43,7 @@ function locale_test_locale_translation_projects_alter(&$projects) {
     // Instead of the default ftp.drupal.org we use the file system of the test
     // instance to simulate a remote file location.
     $url = url(NULL, array('absolute' => TRUE));
-    $remote_url = $url . variable_get('file_public_path', conf_path() . '/files') . '/remote/';
+    $remote_url = $url . PublicStream::basePath() . '/remote/';
 
     // Completely replace the project data with a set of test projects.
     $base_url = url();
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
index 04e98f1..0805bc1 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -17,6 +17,7 @@
 use Drupal\Core\Config\StorageInterface;
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\Language\Language;
+use Drupal\Core\StreamWrapper\PublicStream;
 use ReflectionMethod;
 use ReflectionObject;
 
@@ -708,7 +709,7 @@ public function run(array $methods = array()) {
     if ($simpletest_config->get('verbose')) {
       // Initialize verbose debugging.
       $this->verbose = TRUE;
-      $this->verboseDirectory = variable_get('file_public_path', conf_path() . '/files') . '/simpletest/verbose';
+      $this->verboseDirectory = PublicStream::basePath() . '/simpletest/verbose';
       $this->verboseDirectoryUrl = file_create_url($this->verboseDirectory);
       if (file_prepare_directory($this->verboseDirectory, FILE_CREATE_DIRECTORY) && !file_exists($this->verboseDirectory . '/.htaccess')) {
         file_put_contents($this->verboseDirectory . '/.htaccess', "<IfModule mod_expires.c>\nExpiresActive Off\n</IfModule>\n");
@@ -888,7 +889,9 @@ protected function prepareEnvironment() {
     $this->originalTheme = isset($GLOBALS['theme']) ? $GLOBALS['theme'] : NULL;
 
     // Save further contextual information.
-    $this->originalFileDirectory = variable_get('file_public_path', conf_path() . '/files');
+    // Use the original files directory to avoid nesting it within an existing
+    // simpletest directory if a test is executed within a test.
+    $this->originalFileDirectory = settings()->get('file_public_path', conf_path() . '/files');
     $this->originalProfile = drupal_get_profile();
     $this->originalUser = isset($user) ? clone $user : NULL;
 
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
index c990234..dd725ed 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
@@ -56,7 +56,7 @@ protected function setUp() {
     $conf = array();
     drupal_static_reset();
 
-    $conf['file_public_path'] = $this->public_files_directory;
+    $this->settingsSet('file_public_path', $this->public_files_directory);
 
     // Change the database prefix.
     // All static variables need to be reset before the database prefix is
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 4aec435..9e1ecb8 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -16,6 +16,7 @@
 use Drupal\Core\Language\Language;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Core\Session\UserSession;
+use Drupal\Core\StreamWrapper\PublicStream;
 use PDO;
 use stdClass;
 use DOMDocument;
@@ -416,7 +417,7 @@ protected function drupalGetTestFiles($type, $size = NULL) {
       $original = drupal_get_path('module', 'simpletest') . '/files';
       $files = file_scan_directory($original, '/(html|image|javascript|php|sql)-.*/');
       foreach ($files as $file) {
-        file_unmanaged_copy($file->uri, variable_get('file_public_path', conf_path() . '/files'));
+        file_unmanaged_copy($file->uri, PublicStream::basePath());
       }
 
       $this->generatedTestFiles = TRUE;
@@ -772,7 +773,7 @@ protected function setUp() {
         NestedArray::setValue($GLOBALS['conf'], array_merge(array($config_base), explode('.', $name)), $value);
       }
     }
-    $GLOBALS['conf']['file_public_path'] = $this->public_files_directory;
+    $this->settingsSet('file_public_path', $this->public_files_directory);
     // Execute the non-interactive installer.
     require_once DRUPAL_ROOT . '/core/includes/install.core.inc';
     $this->settingsSet('cache', array('default' => 'cache.backend.memory'));
@@ -820,7 +821,6 @@ protected function setUp() {
       }
       $config->save();
     }
-    variable_set('file_public_path', $this->public_files_directory);
 
     // Use the test mail class instead of the default mail handler class.
     \Drupal::config('system.mail')->set('interface.default', 'Drupal\Core\Mail\VariableLog')->save();
diff --git a/core/modules/system/lib/Drupal/system/Form/FileSystemForm.php b/core/modules/system/lib/Drupal/system/Form/FileSystemForm.php
index 3a4aa18..83cb9e7 100644
--- a/core/modules/system/lib/Drupal/system/Form/FileSystemForm.php
+++ b/core/modules/system/lib/Drupal/system/Form/FileSystemForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Form;
 
+use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\system\SystemConfigFormBase;
 
 /**
@@ -27,12 +28,11 @@ public function getFormID() {
   public function buildForm(array $form, array &$form_state) {
     $config = $this->configFactory->get('system.file');
     $form['file_public_path'] = array(
-      '#type' => 'textfield',
+      '#type' => 'item',
       '#title' => t('Public file system path'),
-      '#default_value' => variable_get('file_public_path', conf_path() . '/files'),
-      '#maxlength' => 255,
-      '#description' => t('A local file system path where public files will be stored. This directory must exist and be writable by Drupal. This directory must be relative to the Drupal installation directory and be accessible over the web.'),
-      '#after_build' => array('system_check_directory'),
+      '#default_value' => PublicStream::basePath(),
+      '#markup' => PublicStream::basePath(),
+      '#description' => t('A local file system path where public files will be stored. This directory must exist and be writable by Drupal. This directory must be relative to the Drupal installation directory and be accessible over the web. This must be changed in settings.php'),
     );
 
     $form['file_private_path'] = array(
@@ -78,7 +78,6 @@ public function submitForm(array &$form, array &$form_state) {
     $config = $this->configFactory->get('system.file')
       ->set('path.private', $form_state['values']['file_private_path'])
       ->set('path.temporary', $form_state['values']['file_temporary_path']);
-    variable_set('file_public_path', $form_state['values']['file_public_path']);
 
     if (isset($form_state['values']['file_default_scheme'])) {
       $config->set('default_scheme', $form_state['values']['file_default_scheme']);
diff --git a/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php b/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php
index 216d0d1..c77b391 100644
--- a/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php
+++ b/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Form;
 
+use Drupal\Core\StreamWrapper\PublicStream;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 use Drupal\Core\Cache\Cache;
@@ -240,7 +241,7 @@ public function buildForm(array $form, array &$form_state, $theme_name = '') {
 
         // Prepare local file path for description.
         if ($original_path && isset($friendly_path)) {
-          $local_file = strtr($original_path, array('public:/' => variable_get('file_public_path', conf_path() . '/files')));
+          $local_file = strtr($original_path, array('public:/' => PublicStream::basePath()));
         }
         elseif ($theme_name) {
           $local_file = drupal_get_path('theme', $theme_name) . '/' . $default;
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/ConfigTest.php b/core/modules/system/lib/Drupal/system/Tests/File/ConfigTest.php
index 7314365..36de9d9 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/ConfigTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/ConfigTest.php
@@ -37,7 +37,6 @@ function testFileConfigurationPage() {
     // upon form submission.
     $file_path = $this->public_files_directory;
     $fields = array(
-      'file_public_path' => $file_path . '/file_config_page_test/public',
       'file_private_path' => $file_path . '/file_config_page_test/private',
       'file_temporary_path' => $file_path . '/file_config_page_test/temporary',
       'file_default_scheme' => 'private',
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/StreamWrapperTest.php b/core/modules/system/lib/Drupal/system/Tests/File/StreamWrapperTest.php
index 1b5c429..16bc592 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/StreamWrapperTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/StreamWrapperTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\File;
 
+use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -82,7 +83,7 @@ function testUriFunctions() {
     // Test file_build_uri() and
     // Drupal\Core\StreamWrapper\LocalStream::getDirectoryPath().
     $this->assertEqual(file_build_uri('foo/bar.txt'), 'public://foo/bar.txt', 'Expected scheme was added.');
-    $this->assertEqual(file_stream_wrapper_get_instance_by_scheme('public')->getDirectoryPath(), variable_get('file_public_path'), 'Expected default directory path was returned.');
+    $this->assertEqual(file_stream_wrapper_get_instance_by_scheme('public')->getDirectoryPath(), PublicStream::basePath(), 'Expected default directory path was returned.');
     $this->assertEqual(file_stream_wrapper_get_instance_by_scheme('temporary')->getDirectoryPath(), $config->get('path.temporary'), 'Expected temporary directory path was returned.');
     $config->set('default_scheme', 'private')->save();
     $this->assertEqual(file_build_uri('foo/bar.txt'), 'private://foo/bar.txt', 'Got a valid URI from foo/bar.txt.');
diff --git a/core/modules/system/lib/Drupal/system/Tests/FileTransfer/FileTransferTest.php b/core/modules/system/lib/Drupal/system/Tests/FileTransfer/FileTransferTest.php
index 080e8fd..066f854 100644
--- a/core/modules/system/lib/Drupal/system/Tests/FileTransfer/FileTransferTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/FileTransfer/FileTransferTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\system\Tests\FileTransfer;
 
 use Drupal\Core\FileTransfer\FileTransferException;
+use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -91,7 +92,7 @@ function testJail() {
 
     $gotit = TRUE;
     try {
-      $this->testConnection->copyDirectory($source, DRUPAL_ROOT . '/'. variable_get('file_public_path', conf_path() . '/files'));
+      $this->testConnection->copyDirectory($source, DRUPAL_ROOT . '/' . PublicStream::basePath());
     }
     catch (FileTransferException $e) {
       $gotit = FALSE;
diff --git a/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php b/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php
index 4358f10..4d5aec1 100644
--- a/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\System;
 
+use Drupal\Core\StreamWrapper\PublicStream;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -45,7 +46,7 @@ function setUp() {
   function testThemeSettings() {
     // Specify a filesystem path to be used for the logo.
     $file = current($this->drupalGetTestFiles('image'));
-    $file_relative = strtr($file->uri, array('public:/' => variable_get('file_public_path', conf_path() . '/files')));
+    $file_relative = strtr($file->uri, array('public:/' => PublicStream::basePath()));
     $default_theme_path = 'core/themes/stark';
 
     $supported_paths = array(
@@ -97,7 +98,7 @@ function testThemeSettings() {
       if (file_uri_scheme($input) == 'public') {
         $implicit_public_file = file_uri_target($input);
         $explicit_file = $input;
-        $local_file = strtr($input, array('public:/' => variable_get('file_public_path', conf_path() . '/files')));
+        $local_file = strtr($input, array('public:/' => PublicStream::basePath()));
       }
       // Adjust for fully qualified stream wrapper URI elsewhere.
       elseif (file_uri_scheme($input) !== FALSE) {
@@ -107,7 +108,7 @@ function testThemeSettings() {
       elseif ($input == file_uri_target($file->uri)) {
         $implicit_public_file = $input;
         $explicit_file = 'public://' . $input;
-        $local_file = variable_get('file_public_path', conf_path() . '/files') . '/' . $input;
+        $local_file = PublicStream::basePath() . '/' . $input;
       }
       $this->assertEqual((string) $elements[0], $implicit_public_file);
       $this->assertEqual((string) $elements[1], $explicit_file);
@@ -134,9 +135,9 @@ function testThemeSettings() {
       // Relative path within the public filesystem to non-existing file.
       'whatever.png',
       // Relative path to non-existing file in public filesystem.
-      variable_get('file_public_path', conf_path() . '/files') . '/whatever.png',
+      PublicStream::basePath() . '/whatever.png',
       // Semi-absolute path to non-existing file in public filesystem.
-      '/' . variable_get('file_public_path', conf_path() . '/files') . '/whatever.png',
+      '/' . PublicStream::basePath() . '/whatever.png',
       // Relative path to arbitrary non-existing file.
       'core/misc/whatever.png',
       // Semi-absolute path to arbitrary non-existing file.
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 3f0fac0..a4e7926 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -9,6 +9,7 @@
 use Drupal\Component\Uuid\Uuid;
 use Drupal\Core\Database\Database;
 use Drupal\Core\Language\Language;
+use Drupal\Core\StreamWrapper\PublicStream;
 
 /**
  * Implements hook_requirements().
@@ -302,7 +303,7 @@ function system_requirements($phase) {
   if ($phase != 'install') {
     $filesystem_config = Drupal::config('system.file');
     $directories = array(
-      variable_get('file_public_path', conf_path() . '/files'),
+      PublicStream::basePath(),
       // By default no private files directory is configured. For private files
       // to be secure the admin needs to provide a path outside the webroot.
       $filesystem_config->get('path.private'),
@@ -315,8 +316,8 @@ function system_requirements($phase) {
   if ($phase == 'install') {
     global $conf;
     $directories = array();
-    if (!empty($conf['file_public_path'])) {
-      $directories[] = $conf['file_public_path'];
+    if ($file_public_path = settings()->get('file_public_path')) {
+      $directories[] = $file_public_path;
     }
     else {
       // If we are installing Drupal, the settings.php file might not exist yet
@@ -2242,6 +2243,15 @@ function system_update_8059() {
 }
 
 /**
+ * Move the file_public_path variable to settings.
+ */
+function system_upgrade_8060() {
+  if ($path = update_variable_get('file_public_path')) {
+    drupal_rewrite_settings(array('settings' => array('file_public_path' => $path)));
+  }
+}
+
+/**
  * @} End of "defgroup updates-7.x-to-8.x".
  * The next series of updates should start at 9000.
  */
diff --git a/core/scripts/run-tests.sh b/core/scripts/run-tests.sh
index 091af6c..31a9c89 100755
--- a/core/scripts/run-tests.sh
+++ b/core/scripts/run-tests.sh
@@ -3,6 +3,7 @@
  * @file
  * This script runs Drupal tests from command line.
  */
+use Drupal\Core\StreamWrapper\PublicStream;
 
 const SIMPLETEST_SCRIPT_COLOR_PASS = 32; // Green.
 const SIMPLETEST_SCRIPT_COLOR_FAIL = 31; // Red.
@@ -399,7 +400,7 @@ function simpletest_script_execute_batch($test_classes) {
           echo 'FATAL ' . $child['class'] . ': test runner returned a non-zero error code (' . $status['exitcode'] . ').' . "\n";
           if ($args['die-on-fail']) {
             list($db_prefix, ) = simpletest_last_test_get($child['test_id']);
-            $public_files = variable_get('file_public_path', conf_path() . '/files');
+            $public_files = PublicStream::basePath();
             $test_directory = $public_files . '/simpletest/' . substr($db_prefix, 10);
             echo 'Simpletest database and files kept and test exited immediately on fail so should be reproducible if you change settings.php to use the database prefix '. $db_prefix . ' and config directories in '. $test_directory . "\n";
             $args['keep-results'] = TRUE;
@@ -568,7 +569,7 @@ function simpletest_script_cleanup($test_id, $test_class, $exitcode) {
 
   // Check whether a test file directory was setup already.
   // @see prepareEnvironment()
-  $public_files = variable_get('file_public_path', conf_path() . '/files');
+  $public_files = PublicStream::basePath();
   $test_directory = $public_files . '/simpletest/' . substr($db_prefix, 10);
   if (is_dir($test_directory)) {
     // Output the error_log.
diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
index fe16cfc..a11647d 100644
--- a/sites/default/default.settings.php
+++ b/sites/default/default.settings.php
@@ -455,6 +455,15 @@
 # $settings['mixed_mode_sessions'] = TRUE;
 
 /**
+ * Public file path:
+ *
+ * A local file system path where public files will be stored. This directory
+ * must exist and be writable by Drupal. This directory must be relative to
+ * the Drupal installation directory and be accessible over the web.
+ */
+# $settings['file_public_path'] = 'sites/default/files';
+
+/**
  * Session write interval:
  *
  * Set the minimum interval between each session write to database.