diff --git a/core/modules/contextual/src/Tests/ContextualDynamicContextTest.php b/core/modules/contextual/src/Tests/ContextualDynamicContextTest.php
index e5d2c85..eef4d80 100644
--- a/core/modules/contextual/src/Tests/ContextualDynamicContextTest.php
+++ b/core/modules/contextual/src/Tests/ContextualDynamicContextTest.php
@@ -184,5 +184,4 @@ protected function renderContextualLinks($ids, $current_path) {
     }
     return $this->drupalPostWithFormat('contextual/render', 'json', $post, array('query' => array('destination' => $current_path)));
   }
-
 }
diff --git a/core/modules/node/src/Tests/Views/NodeContextualLinksTest.php b/core/modules/node/src/Tests/Views/NodeContextualLinksTest.php
index acd7d7b..53526a1 100644
--- a/core/modules/node/src/Tests/Views/NodeContextualLinksTest.php
+++ b/core/modules/node/src/Tests/Views/NodeContextualLinksTest.php
@@ -114,5 +114,4 @@ public function testPageWithDisabledContextualModule() {
     $this->drupalLogin($admin_user);
     $this->drupalGet('node');
   }
-
 }
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
new file mode 100644
index 0000000..507332d
--- /dev/null
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -0,0 +1,3588 @@
+<?php
+
+/**
+ * @file
+ * Definition of \Drupal\simpletest\WebTestBase.
+ */
+
+namespace Drupal\simpletest;
+
+use Drupal\Component\Utility\Crypt;
+use Drupal\Component\Utility\NestedArray;
+use Drupal\Component\Utility\String;
+use Drupal\Core\DrupalKernel;
+use Drupal\Core\Database\Database;
+use Drupal\Core\Database\ConnectionNotDefinedException;
+use Drupal\Core\Language\Language;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\Session\UserSession;
+use Drupal\Core\StreamWrapper\PublicStream;
+use Drupal\Core\Datetime\DrupalDateTime;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Test case for typical Drupal tests.
+ */
+abstract class WebTestBase extends TestBase {
+
+  /**
+   * The profile to install as a basis for testing.
+   *
+   * @var string
+   */
+  protected $profile = 'testing';
+
+  /**
+   * The URL currently loaded in the internal browser.
+   *
+   * @var string
+   */
+  protected $url;
+
+  /**
+   * The handle of the current cURL connection.
+   *
+   * @var resource
+   */
+  protected $curlHandle;
+
+  /**
+   * The headers of the page currently loaded in the internal browser.
+   *
+   * @var Array
+   */
+  protected $headers;
+
+  /**
+   * Indicates that headers should be dumped if verbose output is enabled.
+   *
+   * Headers are dumped to verbose by drupalGet(), drupalHead(), and
+   * drupalPostForm().
+   *
+   * @var bool
+   */
+  protected $dumpHeaders = FALSE;
+
+  /**
+   * The content of the page currently loaded in the internal browser.
+   *
+   * @var string
+   */
+  protected $content;
+
+  /**
+   * The plain-text content of the currently-loaded page.
+   *
+   * @var string
+   */
+  protected $plainTextContent;
+
+  /**
+   * The value of drupalSettings for the currently-loaded page.
+   *
+   * drupalSettings refers to the drupalSettings JavaScript variable.
+   *
+   * @var Array
+   */
+  protected $drupalSettings;
+
+  /**
+   * The parsed version of the page.
+   *
+   * @var \SimpleXMLElement
+   */
+  protected $elements = NULL;
+
+  /**
+   * The current user logged in using the internal browser.
+   *
+   * @var bool
+   */
+  protected $loggedInUser = FALSE;
+
+  /**
+   * The current cookie file used by cURL.
+   *
+   * We do not reuse the cookies in further runs, so we do not need a file
+   * but we still need cookie handling, so we set the jar to NULL.
+   */
+  protected $cookieFile = NULL;
+
+  /**
+   * Additional cURL options.
+   *
+   * \Drupal\simpletest\WebTestBase itself never sets this but always obeys what
+   * is set.
+   */
+  protected $additionalCurlOptions = array();
+
+  /**
+   * The original user, before it was changed to a clean uid = 1 for testing.
+   *
+   * @var object
+   */
+  protected $originalUser = NULL;
+
+  /**
+   * The original shutdown handlers array, before it was cleaned for testing.
+   *
+   * @var array
+   */
+  protected $originalShutdownCallbacks = array();
+
+  /**
+   * HTTP authentication method.
+   */
+  protected $httpauth_method = CURLAUTH_BASIC;
+
+  /**
+   * HTTP authentication credentials (<username>:<password>).
+   */
+  protected $httpauth_credentials = NULL;
+
+  /**
+   * The current session name, if available.
+   */
+  protected $session_name = NULL;
+
+  /**
+   * The current session ID, if available.
+   */
+  protected $session_id = NULL;
+
+  /**
+   * Whether the files were copied to the test files directory.
+   */
+  protected $generatedTestFiles = FALSE;
+
+  /**
+   * The maximum number of redirects to follow when handling responses.
+   */
+  protected $maximumRedirects = 5;
+
+  /**
+   * The number of redirects followed during the handling of a request.
+   */
+  protected $redirect_count;
+
+  /**
+   * The kernel used in this test.
+   */
+  protected $kernel;
+
+  /**
+   * Cookies to set on curl requests.
+   *
+   * @var array
+   */
+  protected $curlCookies = array();
+
+  /**
+   * An array of custom translations suitable for drupal_rewrite_settings().
+   *
+   * @var array
+   */
+  protected $customTranslations;
+
+  /**
+   * Constructor for \Drupal\simpletest\WebTestBase.
+   */
+  function __construct($test_id = NULL) {
+    parent::__construct($test_id);
+    $this->skipClasses[__CLASS__] = TRUE;
+  }
+
+  /**
+   * Get a node from the database based on its title.
+   *
+   * @param $title
+   *   A node title, usually generated by $this->randomName().
+   * @param $reset
+   *   (optional) Whether to reset the entity cache.
+   *
+   * @return \Drupal\Core\Entity\EntityInterface
+   *   A node entity matching $title.
+   */
+  function drupalGetNodeByTitle($title, $reset = FALSE) {
+    if ($reset) {
+      \Drupal::entityManager()->getStorageController('node')->resetCache();
+    }
+    $nodes = entity_load_multiple_by_properties('node', array('title' => $title));
+    // Load the first node returned from the database.
+    $returned_node = reset($nodes);
+    return $returned_node;
+  }
+
+  /**
+   * Creates a node based on default settings.
+   *
+   * @param array $settings
+   *   (optional) An associative array of settings for the node, as used in
+   *   entity_create(). Override the defaults by specifying the key and value
+   *   in the array, for example:
+   *   @code
+   *     $this->drupalCreateNode(array(
+   *       'title' => t('Hello, world!'),
+   *       'type' => 'article',
+   *     ));
+   *   @endcode
+   *   The following defaults are provided:
+   *   - body: Random string using the default filter format:
+   *     @code
+   *       $settings['body'][0] = array(
+   *         'value' => $this->randomName(32),
+   *         'format' => filter_default_format(),
+   *       );
+   *     @endcode
+   *   - title: Random string.
+   *   - comment: COMMENT_OPEN.
+   *   - changed: REQUEST_TIME.
+   *   - promote: NODE_NOT_PROMOTED.
+   *   - log: Empty string.
+   *   - status: NODE_PUBLISHED.
+   *   - sticky: NODE_NOT_STICKY.
+   *   - type: 'page'.
+   *   - langcode: Language::LANGCODE_NOT_SPECIFIED.
+   *   - uid: The currently logged in user, or the user running test.
+   *   - revision: 1. (Backwards-compatible binary flag indicating whether a
+   *     new revision should be created; use 1 to specify a new revision.)
+   *
+   * @return \Drupal\node\Entity\Node
+   *   The created node entity.
+   */
+  protected function drupalCreateNode(array $settings = array()) {
+    // Populate defaults array.
+    $settings += array(
+      'body'      => array(array()),
+      'title'     => $this->randomName(8),
+      'changed'   => REQUEST_TIME,
+      'promote'   => NODE_NOT_PROMOTED,
+      'revision'  => 1,
+      'log'       => '',
+      'status'    => NODE_PUBLISHED,
+      'sticky'    => NODE_NOT_STICKY,
+      'type'      => 'page',
+      'langcode'  => Language::LANGCODE_NOT_SPECIFIED,
+    );
+
+    // Use the original node's created time for existing nodes.
+    if (isset($settings['created']) && !isset($settings['date'])) {
+      $settings['date'] = format_date($settings['created'], 'custom', 'Y-m-d H:i:s O');
+    }
+
+    // If the node's user uid is not specified manually, use the currently
+    // logged in user if available, or else the user running the test.
+    if (!isset($settings['uid'])) {
+      if ($this->loggedInUser) {
+        $settings['uid'] = $this->loggedInUser->id();
+      }
+      else {
+        global $user;
+        $settings['uid'] = $user->id();
+      }
+    }
+
+    // Merge body field value and format separately.
+    $settings['body'][0] += array(
+      'value' => $this->randomName(32),
+      'format' => filter_default_format(),
+    );
+
+    $node = entity_create('node', $settings);
+    if (!empty($settings['revision'])) {
+      $node->setNewRevision();
+    }
+    $node->save();
+
+    return $node;
+  }
+
+  /**
+   * Creates a custom content type based on default settings.
+   *
+   * @param array $values
+   *   An array of settings to change from the defaults.
+   *   Example: 'type' => 'foo'.
+   *
+   * @return \Drupal\node\Entity\NodeType
+   *   Created content type.
+   */
+  protected function drupalCreateContentType(array $values = array()) {
+    // Find a non-existent random type name.
+    if (!isset($values['type'])) {
+      do {
+        $id = strtolower($this->randomName(8));
+      } while (node_type_load($id));
+    }
+    else {
+      $id = $values['type'];
+    }
+    $values += array(
+      'type' => $id,
+      'name' => $id,
+    );
+    $type = entity_create('node_type', $values);
+    $status = $type->save();
+    menu_router_rebuild();
+
+    $this->assertEqual($status, SAVED_NEW, t('Created content type %type.', array('%type' => $type->id())));
+
+    // Reset permissions so that permissions for this content type are
+    // available.
+    $this->checkPermissions(array(), TRUE);
+
+    return $type;
+  }
+
+  /**
+   * Creates a block instance based on default settings.
+   *
+   * Note: Until this can be done programmatically, the active user account
+   * must have permission to administer blocks.
+   *
+   * @param string $plugin_id
+   *   The plugin ID of the block type for this block instance.
+   * @param array $settings
+   *   (optional) An associative array of settings for the block entity.
+   *   Override the defaults by specifying the key and value in the array, for
+   *   example:
+   *   @code
+   *     $this->drupalPlaceBlock('system_powered_by_block', array(
+   *       'label' => t('Hello, world!'),
+   *     ));
+   *   @endcode
+   *   The following defaults are provided:
+   *   - label: Random string.
+   *   - id: Random string.
+   *   - region: 'sidebar_first'.
+   *   - theme: The default theme.
+   *   - visibility: Empty array.
+   *
+   * @return \Drupal\block\Entity\Block
+   *   The block entity.
+   *
+   * @todo
+   *   Add support for creating custom block instances.
+   */
+  protected function drupalPlaceBlock($plugin_id, array $settings = array()) {
+    $settings += array(
+      'plugin' => $plugin_id,
+      'region' => 'sidebar_first',
+      'id' => strtolower($this->randomName(8)),
+      'theme' => \Drupal::config('system.theme')->get('default'),
+      'label' => $this->randomName(8),
+      'visibility' => array(),
+      'weight' => 0,
+    );
+    foreach (array('region', 'id', 'theme', 'plugin', 'visibility', 'weight') as $key) {
+      $values[$key] = $settings[$key];
+      // Remove extra values that do not belong in the settings array.
+      unset($settings[$key]);
+    }
+    $values['settings'] = $settings;
+    $block = entity_create('block', $values);
+    $block->save();
+    return $block;
+  }
+
+  /**
+   * Gets a list files that can be used in tests.
+   *
+   * @param $type
+   *   File type, possible values: 'binary', 'html', 'image', 'javascript',
+   *   'php', 'sql', 'text'.
+   * @param $size
+   *   File size in bytes to match. Please check the tests/files folder.
+   *
+   * @return
+   *   List of files that match filter.
+   */
+  protected function drupalGetTestFiles($type, $size = NULL) {
+    if (empty($this->generatedTestFiles)) {
+      // Generate binary test files.
+      $lines = array(64, 1024);
+      $count = 0;
+      foreach ($lines as $line) {
+        simpletest_generate_file('binary-' . $count++, 64, $line, 'binary');
+      }
+
+      // Generate text test files.
+      $lines = array(16, 256, 1024, 2048, 20480);
+      $count = 0;
+      foreach ($lines as $line) {
+        simpletest_generate_file('text-' . $count++, 64, $line);
+      }
+
+      // Copy other test files from simpletest.
+      $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, PublicStream::basePath());
+      }
+
+      $this->generatedTestFiles = TRUE;
+    }
+
+    $files = array();
+    // Make sure type is valid.
+    if (in_array($type, array('binary', 'html', 'image', 'javascript', 'php', 'sql', 'text'))) {
+      $files = file_scan_directory('public://', '/' . $type . '\-.*/');
+
+      // If size is set then remove any files that are not of that size.
+      if ($size !== NULL) {
+        foreach ($files as $file) {
+          $stats = stat($file->uri);
+          if ($stats['size'] != $size) {
+            unset($files[$file->uri]);
+          }
+        }
+      }
+    }
+    usort($files, array($this, 'drupalCompareFiles'));
+    return $files;
+  }
+
+  /**
+   * Compare two files based on size and file name.
+   */
+  protected function drupalCompareFiles($file1, $file2) {
+    $compare_size = filesize($file1->uri) - filesize($file2->uri);
+    if ($compare_size) {
+      // Sort by file size.
+      return $compare_size;
+    }
+    else {
+      // The files were the same size, so sort alphabetically.
+      return strnatcmp($file1->name, $file2->name);
+    }
+  }
+
+  /**
+   * Create a user with a given set of permissions.
+   *
+   * @param array $permissions
+   *   Array of permission names to assign to user. Note that the user always
+   *   has the default permissions derived from the "authenticated users" role.
+   * @param string $name
+   *   The user name.
+   *
+   * @return \Drupal\user\Entity\User|false
+   *   A fully loaded user object with pass_raw property, or FALSE if account
+   *   creation fails.
+   */
+  protected function drupalCreateUser(array $permissions = array(), $name = NULL) {
+    // Create a role with the given permission set, if any.
+    $rid = FALSE;
+    if ($permissions) {
+      $rid = $this->drupalCreateRole($permissions);
+      if (!$rid) {
+        return FALSE;
+      }
+    }
+
+    // Create a user assigned to that role.
+    $edit = array();
+    $edit['name']   = !empty($name) ? $name : $this->randomName();
+    $edit['mail']   = $edit['name'] . '@example.com';
+    $edit['pass']   = user_password();
+    $edit['status'] = 1;
+    if ($rid) {
+      $edit['roles'] = array($rid);
+    }
+
+    $account = entity_create('user', $edit);
+    $account->save();
+
+    $this->assertTrue($account->id(), String::format('User created with name %name and pass %pass', array('%name' => $edit['name'], '%pass' => $edit['pass'])), 'User login');
+    if (!$account->id()) {
+      return FALSE;
+    }
+
+    // Add the raw password so that we can log in as this user.
+    $account->pass_raw = $edit['pass'];
+    return $account;
+  }
+
+  /**
+   * Internal helper function; Create a role with specified permissions.
+   *
+   * @param array $permissions
+   *   Array of permission names to assign to role.
+   * @param string $rid
+   *   (optional) The role ID (machine name). Defaults to a random name.
+   * @param string $name
+   *   (optional) The label for the role. Defaults to a random string.
+   * @param integer $weight
+   *   (optional) The weight for the role. Defaults NULL so that entity_create()
+   *   sets the weight to maximum + 1.
+   *
+   * @return string
+   *   Role ID of newly created role, or FALSE if role creation failed.
+   */
+  protected function drupalCreateRole(array $permissions, $rid = NULL, $name = NULL, $weight = NULL) {
+    // Generate a random, lowercase machine name if none was passed.
+    if (!isset($rid)) {
+      $rid = strtolower($this->randomName(8));
+    }
+    // Generate a random label.
+    if (!isset($name)) {
+      // In the role UI role names are trimmed and random string can start or
+      // end with a space.
+      $name = trim($this->randomString(8));
+    }
+
+    // Check the all the permissions strings are valid.
+    if (!$this->checkPermissions($permissions)) {
+      return FALSE;
+    }
+
+    // Create new role.
+    $role = entity_create('user_role', array(
+      'id' => $rid,
+      'label' => $name,
+    ));
+    if (!is_null($weight)) {
+      $role->set('weight', $weight);
+    }
+    $result = $role->save();
+
+    $this->assertIdentical($result, SAVED_NEW, t('Created role ID @rid with name @name.', array(
+      '@name' => var_export($role->label(), TRUE),
+      '@rid' => var_export($role->id(), TRUE),
+    )), t('Role'));
+
+    if ($result === SAVED_NEW) {
+      // Grant the specified permissions to the role, if any.
+      if (!empty($permissions)) {
+        user_role_grant_permissions($role->id(), $permissions);
+        $assigned_permissions = entity_load('user_role', $role->id())->permissions;
+        $missing_permissions = array_diff($permissions, $assigned_permissions);
+        if (!$missing_permissions) {
+          $this->pass(t('Created permissions: @perms', array('@perms' => implode(', ', $permissions))), t('Role'));
+        }
+        else {
+          $this->fail(t('Failed to create permissions: @perms', array('@perms' => implode(', ', $missing_permissions))), t('Role'));
+        }
+      }
+      return $role->id();
+    }
+    else {
+      return FALSE;
+    }
+  }
+
+  /**
+   * Check to make sure that the array of permissions are valid.
+   *
+   * @param $permissions
+   *   Permissions to check.
+   * @param $reset
+   *   Reset cached available permissions.
+   *
+   * @return
+   *   TRUE or FALSE depending on whether the permissions are valid.
+   */
+  protected function checkPermissions(array $permissions, $reset = FALSE) {
+    $available = &drupal_static(__FUNCTION__);
+
+    if (!isset($available) || $reset) {
+      $available = array_keys(module_invoke_all('permission'));
+    }
+
+    $valid = TRUE;
+    foreach ($permissions as $permission) {
+      if (!in_array($permission, $available)) {
+        $this->fail(t('Invalid permission %permission.', array('%permission' => $permission)), t('Role'));
+        $valid = FALSE;
+      }
+    }
+    return $valid;
+  }
+
+  /**
+   * Log in a user with the internal browser.
+   *
+   * If a user is already logged in, then the current user is logged out before
+   * logging in the specified user.
+   *
+   * Please note that neither the global $user nor the passed-in user object is
+   * populated with data of the logged in user. If you need full access to the
+   * user object after logging in, it must be updated manually. If you also need
+   * access to the plain-text password of the user (set by drupalCreateUser()),
+   * e.g. to log in the same user again, then it must be re-assigned manually.
+   * For example:
+   * @code
+   *   // Create a user.
+   *   $account = $this->drupalCreateUser(array());
+   *   $this->drupalLogin($account);
+   *   // Load real user object.
+   *   $pass_raw = $account->pass_raw;
+   *   $account = user_load($account->id());
+   *   $account->pass_raw = $pass_raw;
+   * @endcode
+   *
+   * @param \Drupal\Core\Session\AccountInterface $account
+   *   User object representing the user to log in.
+   *
+   * @see drupalCreateUser()
+   */
+  protected function drupalLogin(AccountInterface $account) {
+    if ($this->loggedInUser) {
+      $this->drupalLogout();
+    }
+
+    $edit = array(
+      'name' => $account->getUsername(),
+      'pass' => $account->pass_raw
+    );
+    $this->drupalPostForm('user', $edit, t('Log in'));
+
+    // @see WebTestBase::drupalUserIsLoggedIn()
+    if (isset($this->session_id)) {
+      $account->session_id = $this->session_id;
+    }
+    $pass = $this->assert($this->drupalUserIsLoggedIn($account), format_string('User %name successfully logged in.', array('%name' => $account->getUsername())), 'User login');
+    if ($pass) {
+      $this->loggedInUser = $account;
+      $this->container->set('current_user', $account);
+    }
+  }
+
+  /**
+   * Returns whether a given user account is logged in.
+   *
+   * @param \Drupal\user\UserInterface $account
+   *   The user account object to check.
+   */
+  protected function drupalUserIsLoggedIn($account) {
+    if (!isset($account->session_id)) {
+      return FALSE;
+    }
+    // @see _drupal_session_read()
+    return (bool) db_query("SELECT sid FROM {users} u INNER JOIN {sessions} s ON u.uid = s.uid WHERE s.sid = :sid", array(':sid' => $account->session_id))->fetchField();
+  }
+
+  /**
+   * Generate a token for the currently logged in user.
+   */
+  protected function drupalGetToken($value = '') {
+    $private_key = drupal_get_private_key();
+    return Crypt::hmacBase64($value, $this->session_id . $private_key);
+  }
+
+  /**
+   * Logs a user out of the internal browser and confirms.
+   *
+   * Confirms logout by checking the login page.
+   */
+  protected function drupalLogout() {
+    // Make a request to the logout page, and redirect to the user page, the
+    // idea being if you were properly logged out you should be seeing a login
+    // screen.
+    $this->drupalGet('user/logout', array('query' => array('destination' => 'user')));
+    $this->assertResponse(200, 'User was logged out.');
+    $pass = $this->assertField('name', 'Username field found.', 'Logout');
+    $pass = $pass && $this->assertField('pass', 'Password field found.', 'Logout');
+
+    if ($pass) {
+      // @see WebTestBase::drupalUserIsLoggedIn()
+      unset($this->loggedInUser->session_id);
+      $this->loggedInUser = FALSE;
+      $this->container->set('current_user', drupal_anonymous_user());
+    }
+  }
+
+  /**
+   * Sets up a Drupal site for running functional and integration tests.
+   *
+   * Generates a random database prefix and installs Drupal with the specified
+   * installation profile in \Drupal\simpletest\WebTestBase::$profile into the
+   * prefixed database. Afterwards, installs any additional modules specified by
+   * the test.
+   *
+   * After installation all caches are flushed and several configuration values
+   * are reset to the values of the parent site executing the test, since the
+   * default values may be incompatible with the environment in which tests are
+   * being executed.
+   *
+   * @param ...
+   *   List of modules to enable for the duration of the test. This can be
+   *   either a single array or a variable number of string arguments.
+   *
+   * @see \Drupal\simpletest\WebTestBase::prepareDatabasePrefix()
+   * @see \Drupal\simpletest\WebTestBase::changeDatabasePrefix()
+   * @see \Drupal\simpletest\WebTestBase::prepareEnvironment()
+   */
+  protected function setUp() {
+    global $user, $conf;
+
+    // When running tests through the Simpletest UI (vs. on the command line),
+    // Simpletest's batch conflicts with the installer's batch. Batch API does
+    // not support the concept of nested batches (in which the nested is not
+    // progressive), so we need to temporarily pretend there was no batch.
+    // Backup the currently running Simpletest batch.
+    $this->originalBatch = batch_get();
+
+    // Create the database prefix for this test.
+    $this->prepareDatabasePrefix();
+
+    // Prepare the environment for running tests.
+    $this->prepareEnvironment();
+    if (!$this->setupEnvironment) {
+      return FALSE;
+    }
+
+    // Reset all statics and variables to perform tests in a clean environment.
+    $conf = array();
+    drupal_static_reset();
+
+    // Change the database prefix.
+    // All static variables need to be reset before the database prefix is
+    // changed, since \Drupal\Core\Utility\CacheArray implementations attempt to
+    // write back to persistent caches when they are destructed.
+    $this->changeDatabasePrefix();
+    if (!$this->setupDatabasePrefix) {
+      return FALSE;
+    }
+
+    // Set the 'simpletest_parent_profile' variable to add the parent profile's
+    // search path to the child site's search paths.
+    // @see drupal_system_listing()
+    $conf['simpletest_parent_profile'] = $this->originalProfile;
+
+    // Define information about the user 1 account.
+    $this->root_user = new UserSession(array(
+      'uid' => 1,
+      'name' => 'admin',
+      'mail' => 'admin@example.com',
+      'pass_raw' => $this->randomName(),
+    ));
+
+    // Reset the static batch to remove Simpletest's batch operations.
+    $batch = &batch_get();
+    $batch = array();
+    $variable_groups = array(
+      'system.file' => array(
+        'path.private' =>  $this->private_files_directory,
+        'path.temporary' =>  $this->temp_files_directory,
+      ),
+      'locale.settings' =>  array(
+        'translation.path' => $this->translation_files_directory,
+      ),
+    );
+    foreach ($variable_groups as $config_base => $variables) {
+      foreach ($variables as $name => $value) {
+        NestedArray::setValue($GLOBALS['conf'], array_merge(array($config_base), explode('.', $name)), $value);
+      }
+    }
+    $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'));
+    $parameters = $this->installParameters();
+    install_drupal($parameters);
+
+    // Set the install_profile so that web requests to the requests to the child
+    // site have the correct profile.
+    $settings = array(
+      'settings' => array(
+        'install_profile' => (object) array(
+          'value' => $this->profile,
+          'required' => TRUE,
+        ),
+      ),
+    );
+    $this->writeSettings($settings);
+    // Override install profile in Settings to so the correct profile is used by
+    // tests.
+    $this->settingsSet('install_profile', $this->profile);
+
+    $this->settingsSet('cache', array());
+    $this->rebuildContainer();
+
+    // Restore the original Simpletest batch.
+    $batch = &batch_get();
+    $batch = $this->originalBatch;
+
+    // Set path variables.
+
+    // Set 'parent_profile' of simpletest to add the parent profile's
+    // search path to the child site's search paths.
+    // @see drupal_system_listing()
+    \Drupal::config('simpletest.settings')->set('parent_profile', $this->originalProfile)->save();
+
+    // Collect modules to install.
+    $class = get_class($this);
+    $modules = array();
+    while ($class) {
+      if (property_exists($class, 'modules')) {
+        $modules = array_merge($modules, $class::$modules);
+      }
+      $class = get_parent_class($class);
+    }
+    if ($modules) {
+      $modules = array_unique($modules);
+      $success = \Drupal::moduleHandler()->install($modules, TRUE);
+      $this->assertTrue($success, t('Enabled modules: %modules', array('%modules' => implode(', ', $modules))));
+      $this->rebuildContainer();
+    }
+
+    // Reset/rebuild all data structures after enabling the modules.
+    $this->resetAll();
+
+    // Now make sure that the file path configurations are saved. This is done
+    // after we install the modules to override default values.
+    foreach ($variable_groups as $config_base => $variables) {
+      $config = \Drupal::config($config_base);
+      foreach ($variables as $name => $value) {
+        $config->set($name, $value);
+      }
+      $config->save();
+    }
+
+    // Use the test mail class instead of the default mail handler class.
+    \Drupal::config('system.mail')->set('interface.default', 'Drupal\Core\Mail\VariableLog')->save();
+
+    drupal_set_time_limit($this->timeLimit);
+    // Temporary fix so that when running from run-tests.sh we don't get an
+    // empty current path which would indicate we're on the home page.
+    $path = current_path();
+    if (empty($path)) {
+      _current_path('run-tests');
+    }
+    $this->setup = TRUE;
+  }
+
+  /**
+   * Returns the parameters that will be used when Simpletest installs Drupal.
+   *
+   * @see install_drupal()
+   * @see install_state_defaults()
+   */
+  protected function installParameters() {
+    $connection_info = Database::getConnectionInfo();
+    $parameters = array(
+      'interactive' => FALSE,
+      'parameters' => array(
+        'profile' => $this->profile,
+        'langcode' => 'en',
+      ),
+      'forms' => array(
+        'install_settings_form' => $connection_info['default'],
+        'install_configure_form' => array(
+          'site_name' => 'Drupal',
+          'site_mail' => 'simpletest@example.com',
+          'account' => array(
+            'name' => $this->root_user->name,
+            'mail' => $this->root_user->getEmail(),
+            'pass' => array(
+              'pass1' => $this->root_user->pass_raw,
+              'pass2' => $this->root_user->pass_raw,
+            ),
+          ),
+          // form_type_checkboxes_value() requires NULL instead of FALSE values
+          // for programmatic form submissions to disable a checkbox.
+          'update_status_module' => array(
+            1 => NULL,
+            2 => NULL,
+          ),
+        ),
+      ),
+    );
+    return $parameters;
+  }
+
+  /**
+   * Writes a test-specific settings.php file for the child site.
+   *
+   * The child site loads this after the parent site's settings.php, so settings
+   * here override those.
+   *
+   * @param $settings An array of settings to write out, in the format expected
+   *   by drupal_rewrite_settings().
+   *
+   * @see _drupal_load_test_overrides()
+   * @see drupal_rewrite_settings()
+   */
+  protected function writeSettings($settings) {
+    // drupal_rewrite_settings() sets the in-memory global variables in addition
+    // to writing the file. We'll want to restore the original globals.
+    foreach (array_keys($settings) as $variable_name) {
+      $original_globals[$variable_name] = isset($GLOBALS[$variable_name]) ? $GLOBALS[$variable_name] : NULL;
+    }
+
+    include_once DRUPAL_ROOT . '/core/includes/install.inc';
+    $filename = $this->public_files_directory . '/settings.php';
+    file_put_contents($filename, "<?php\n");
+    drupal_rewrite_settings($settings, $filename);
+
+    // Restore the original globals.
+    foreach ($original_globals as $variable_name => $value) {
+      $GLOBALS[$variable_name] = $value;
+    }
+  }
+
+  /**
+   * Sets custom translations to the settings object and queues them to writing.
+   *
+   * In order for those custom translations to persist (being written in test
+   * site's settings.php) make sure to also call self::writeCustomTranslations()
+   *
+   * @param string $langcode
+   *   The langcode to add translations for.
+   * @param array $values
+   *   Array of values containing the untranslated string and its translation.
+   *   For example:
+   *   @code
+   *   array(
+   *     '' => array('Sunday' => 'domingo'),
+   *     'Long month name' => array('March' => 'marzo'),
+   *   );
+   *   @endcode
+   */
+  protected function addCustomTranslations($langcode, array $values) {
+    $this->settingsSet('locale_custom_strings_' . $langcode, $values);
+    foreach ($values as $key => $translations) {
+      foreach ($translations as $label => $value) {
+        $this->customTranslations['locale_custom_strings_' . $langcode][$key][$label] = (object) array(
+          'value' => $value,
+          'required' => TRUE,
+        );
+      }
+    }
+  }
+
+  /**
+   * Writes custom translations to test site's settings.php.
+   */
+  protected function writeCustomTranslations() {
+    $this->writeSettings(array('settings' => $this->customTranslations));
+    $this->customTranslations = array();
+  }
+
+  /**
+   * Overrides \Drupal\simpletest\TestBase::rebuildContainer().
+   */
+  protected function rebuildContainer() {
+    parent::rebuildContainer();
+    // Make sure the url generator has a request object, otherwise calls to
+    // $this->drupalGet() will fail.
+    $this->prepareRequestForGenerator();
+  }
+
+  /**
+   * Resets all data structures after having enabled new modules.
+   *
+   * This method is called by \Drupal\simpletest\WebTestBase::setUp() after
+   * enabling the requested modules. It must be called again when additional
+   * modules are enabled later.
+   */
+  protected function resetAll() {
+    // Clear all database and static caches and rebuild data structures.
+    drupal_flush_all_caches();
+    $this->container = \Drupal::getContainer();
+
+    // Reload global $conf array and permissions.
+    $this->refreshVariables();
+    $this->checkPermissions(array(), TRUE);
+  }
+
+  /**
+   * Refreshes the in-memory set of variables.
+   *
+   * Useful after a page request is made that changes a variable in a different
+   * thread.
+   *
+   * In other words calling a settings page with $this->drupalPostForm() with a
+   * changed value would update a variable to reflect that change, but in the
+   * thread that made the call (thread running the test) the changed variable
+   * would not be picked up.
+   *
+   * This method clears the variables cache and loads a fresh copy from the
+   * database to ensure that the most up-to-date set of variables is loaded.
+   */
+  protected function refreshVariables() {
+    global $conf;
+    cache('bootstrap')->delete('variables');
+    $conf = variable_initialize();
+    // Clear the tag cache.
+    drupal_static_reset('Drupal\Core\Cache\CacheBackendInterface::tagCache');
+    drupal_container()->get('config.factory')->reset();
+  }
+
+  /**
+   * Cleans up after testing.
+   *
+   * Deletes created files and temporary files directory, deletes the tables
+   * created by setUp(), and resets the database prefix.
+   */
+  protected function tearDown() {
+    // Destroy the testing kernel.
+    if (isset($this->kernel)) {
+      $this->kernel->shutdown();
+    }
+    parent::tearDown();
+
+    // Ensure that internal logged in variable and cURL options are reset.
+    $this->loggedInUser = FALSE;
+    $this->additionalCurlOptions = array();
+
+    // Close the CURL handler and reset the cookies array used for upgrade
+    // testing so test classes containing multiple tests are not polluted.
+    $this->curlClose();
+    $this->curlCookies = array();
+  }
+
+  /**
+   * Initializes the cURL connection.
+   *
+   * If the simpletest_httpauth_credentials variable is set, this function will
+   * add HTTP authentication headers. This is necessary for testing sites that
+   * are protected by login credentials from public access.
+   * See the description of $curl_options for other options.
+   */
+  protected function curlInitialize() {
+    global $base_url;
+
+    if (!isset($this->curlHandle)) {
+      $this->curlHandle = curl_init();
+
+      // Some versions/configurations of cURL break on a NULL cookie jar, so
+      // supply a real file.
+      if (empty($this->cookieFile)) {
+        $this->cookieFile = $this->public_files_directory . '/cookie.jar';
+      }
+
+      $curl_options = array(
+        CURLOPT_COOKIEJAR => $this->cookieFile,
+        CURLOPT_URL => $base_url,
+        CURLOPT_FOLLOWLOCATION => FALSE,
+        CURLOPT_RETURNTRANSFER => TRUE,
+        // Required to make the tests run on HTTPS.
+        CURLOPT_SSL_VERIFYPEER => FALSE,
+        // Required to make the tests run on HTTPS.
+        CURLOPT_SSL_VERIFYHOST => FALSE,
+        CURLOPT_HEADERFUNCTION => array(&$this, 'curlHeaderCallback'),
+        CURLOPT_USERAGENT => $this->databasePrefix,
+      );
+      if (isset($this->httpauth_credentials)) {
+        $curl_options[CURLOPT_HTTPAUTH] = $this->httpauth_method;
+        $curl_options[CURLOPT_USERPWD] = $this->httpauth_credentials;
+      }
+      // curl_setopt_array() returns FALSE if any of the specified options
+      // cannot be set, and stops processing any further options.
+      $result = curl_setopt_array($this->curlHandle, $this->additionalCurlOptions + $curl_options);
+      if (!$result) {
+        throw new \UnexpectedValueException('One or more cURL options could not be set.');
+      }
+
+      // By default, the child session name should be the same as the parent.
+      $this->session_name = session_name();
+    }
+    // We set the user agent header on each request so as to use the current
+    // time and a new uniqid.
+    if (preg_match('/simpletest\d+/', $this->databasePrefix, $matches)) {
+      curl_setopt($this->curlHandle, CURLOPT_USERAGENT, drupal_generate_test_ua($matches[0]));
+    }
+  }
+
+  /**
+   * Initializes and executes a cURL request.
+   *
+   * @param $curl_options
+   *   An associative array of cURL options to set, where the keys are constants
+   *   defined by the cURL library. For a list of valid options, see
+   *   http://www.php.net/manual/function.curl-setopt.php
+   * @param $redirect
+   *   FALSE if this is an initial request, TRUE if this request is the result
+   *   of a redirect.
+   *
+   * @return
+   *   The content returned from the call to curl_exec().
+   *
+   * @see curlInitialize()
+   */
+  protected function curlExec($curl_options, $redirect = FALSE) {
+    $this->curlInitialize();
+
+    if (!empty($curl_options[CURLOPT_URL])) {
+      // cURL incorrectly handles URLs with a fragment by including the
+      // fragment in the request to the server, causing some web servers
+      // to reject the request citing "400 - Bad Request". To prevent
+      // this, we strip the fragment from the request.
+      // TODO: Remove this for Drupal 8, since fixed in curl 7.20.0.
+      if (strpos($curl_options[CURLOPT_URL], '#')) {
+        $original_url = $curl_options[CURLOPT_URL];
+        $curl_options[CURLOPT_URL] = strtok($curl_options[CURLOPT_URL], '#');
+      }
+    }
+
+    $url = empty($curl_options[CURLOPT_URL]) ? curl_getinfo($this->curlHandle, CURLINFO_EFFECTIVE_URL) : $curl_options[CURLOPT_URL];
+
+    if (!empty($curl_options[CURLOPT_POST])) {
+      // This is a fix for the Curl library to prevent Expect: 100-continue
+      // headers in POST requests, that may cause unexpected HTTP response
+      // codes from some webservers (like lighttpd that returns a 417 error
+      // code). It is done by setting an empty "Expect" header field that is
+      // not overwritten by Curl.
+      $curl_options[CURLOPT_HTTPHEADER][] = 'Expect:';
+    }
+
+    $cookies = array();
+    if (!empty($this->curlCookies)) {
+      $cookies = $this->curlCookies;
+    }
+    // In order to debug webtests you need to either set a cookie or have the
+    // xdebug session in the URL. If the developer listens to connection on the
+    // parent site, by default the cookie is not forwarded to the client side,
+    // so you can't debug actual running code. In order to make debuggers work
+    // this bit of information is forwarded. Make sure that the debugger listens
+    // to at least three external connections.
+    if (isset($_COOKIE['XDEBUG_SESSION'])) {
+      $cookies[] = 'XDEBUG_SESSION=' . $_COOKIE['XDEBUG_SESSION'];
+    }
+
+    // Merge additional cookies in.
+    if (!empty($cookies)) {
+      $curl_options += array(
+        CURLOPT_COOKIE => '',
+      );
+      // Ensure any existing cookie data string ends with the correct separator.
+      if (!empty($curl_options[CURLOPT_COOKIE])) {
+        $curl_options[CURLOPT_COOKIE] = rtrim($curl_options[CURLOPT_COOKIE], '; ') . '; ';
+      }
+      $curl_options[CURLOPT_COOKIE] .= implode('; ', $cookies) . ';';
+    }
+
+    curl_setopt_array($this->curlHandle, $this->additionalCurlOptions + $curl_options);
+
+    if (!$redirect) {
+      // Reset headers, the session ID and the redirect counter.
+      $this->session_id = NULL;
+      $this->headers = array();
+      $this->redirect_count = 0;
+    }
+
+    $content = curl_exec($this->curlHandle);
+    $status = curl_getinfo($this->curlHandle, CURLINFO_HTTP_CODE);
+
+    // cURL incorrectly handles URLs with fragments, so instead of
+    // letting cURL handle redirects we take of them ourselves to
+    // to prevent fragments being sent to the web server as part
+    // of the request.
+    // TODO: Remove this for Drupal 8, since fixed in curl 7.20.0.
+    if (in_array($status, array(300, 301, 302, 303, 305, 307)) && $this->redirect_count < $this->maximumRedirects) {
+      if ($this->drupalGetHeader('location')) {
+        $this->redirect_count++;
+        $curl_options = array();
+        $curl_options[CURLOPT_URL] = $this->drupalGetHeader('location');
+        $curl_options[CURLOPT_HTTPGET] = TRUE;
+        return $this->curlExec($curl_options, TRUE);
+      }
+    }
+
+    $this->drupalSetContent($content, isset($original_url) ? $original_url : curl_getinfo($this->curlHandle, CURLINFO_EFFECTIVE_URL));
+    $message_vars = array(
+      '!method' => !empty($curl_options[CURLOPT_NOBODY]) ? 'HEAD' : (empty($curl_options[CURLOPT_POSTFIELDS]) ? 'GET' : 'POST'),
+      '@url' => isset($original_url) ? $original_url : $url,
+      '@status' => $status,
+      '!length' => format_size(strlen($this->drupalGetContent()))
+    );
+    $message = String::format('!method @url returned @status (!length).', $message_vars);
+    $this->assertTrue($this->drupalGetContent() !== FALSE, $message, 'Browser');
+    return $this->drupalGetContent();
+  }
+
+  /**
+   * Reads headers and registers errors received from the tested site.
+   *
+   * @param $curlHandler
+   *   The cURL handler.
+   * @param $header
+   *   An header.
+   *
+   * @see _drupal_log_error().
+   */
+  protected function curlHeaderCallback($curlHandler, $header) {
+    // Header fields can be extended over multiple lines by preceding each
+    // extra line with at least one SP or HT. They should be joined on receive.
+    // Details are in RFC2616 section 4.
+    if ($header[0] == ' ' || $header[0] == "\t") {
+      // Normalize whitespace between chucks.
+      $this->headers[] = array_pop($this->headers) . ' ' . trim($header);
+    }
+    else {
+      $this->headers[] = $header;
+    }
+
+    // Errors are being sent via X-Drupal-Assertion-* headers,
+    // generated by _drupal_log_error() in the exact form required
+    // by \Drupal\simpletest\WebTestBase::error().
+    if (preg_match('/^X-Drupal-Assertion-[0-9]+: (.*)$/', $header, $matches)) {
+      // Call \Drupal\simpletest\WebTestBase::error() with the parameters from
+      // the header.
+      call_user_func_array(array(&$this, 'error'), unserialize(urldecode($matches[1])));
+    }
+
+    // Save cookies.
+    if (preg_match('/^Set-Cookie: ([^=]+)=(.+)/', $header, $matches)) {
+      $name = $matches[1];
+      $parts = array_map('trim', explode(';', $matches[2]));
+      $value = array_shift($parts);
+      $this->cookies[$name] = array('value' => $value, 'secure' => in_array('secure', $parts));
+      if ($name == $this->session_name) {
+        if ($value != 'deleted') {
+          $this->session_id = $value;
+        }
+        else {
+          $this->session_id = NULL;
+        }
+      }
+    }
+
+    // This is required by cURL.
+    return strlen($header);
+  }
+
+  /**
+   * Close the cURL handler and unset the handler.
+   */
+  protected function curlClose() {
+    if (isset($this->curlHandle)) {
+      curl_close($this->curlHandle);
+      unset($this->curlHandle);
+    }
+  }
+
+  /**
+   * Parse content returned from curlExec using DOM and SimpleXML.
+   *
+   * @return
+   *   A SimpleXMLElement or FALSE on failure.
+   */
+  protected function parse() {
+    if (!$this->elements) {
+      // DOM can load HTML soup. But, HTML soup can throw warnings, suppress
+      // them.
+      $htmlDom = new \DOMDocument();
+      @$htmlDom->loadHTML('<?xml encoding="UTF-8">' . $this->drupalGetContent());
+      if ($htmlDom) {
+        $this->pass(t('Valid HTML found on "@path"', array('@path' => $this->getUrl())), t('Browser'));
+        // It's much easier to work with simplexml than DOM, luckily enough
+        // we can just simply import our DOM tree.
+        $this->elements = simplexml_import_dom($htmlDom);
+      }
+    }
+    if (!$this->elements) {
+      $this->fail(t('Parsed page successfully.'), t('Browser'));
+    }
+
+    return $this->elements;
+  }
+
+  /**
+   * Retrieves a Drupal path or an absolute path.
+   *
+   * @param $path
+   *   Drupal path or URL to load into internal browser
+   * @param $options
+   *   Options to be forwarded to the url generator.
+   * @param $headers
+   *   An array containing additional HTTP request headers, each formatted as
+   *   "name: value".
+   *
+   * @return
+   *   The retrieved HTML string, also available as $this->drupalGetContent()
+   */
+  protected function drupalGet($path, array $options = array(), array $headers = array()) {
+    $options['absolute'] = TRUE;
+
+    // We re-using a CURL connection here. If that connection still has certain
+    // options set, it might change the GET into a POST. Make sure we clear out
+    // previous options.
+    $url = $this->container->get('url_generator')->generateFromPath($path, $options);
+    $out = $this->curlExec(array(CURLOPT_HTTPGET => TRUE, CURLOPT_URL => $url, CURLOPT_NOBODY => FALSE, CURLOPT_HTTPHEADER => $headers));
+    // Ensure that any changes to variables in the other thread are picked up.
+    $this->refreshVariables();
+
+    // Replace original page output with new output from redirected page(s).
+    if ($new = $this->checkForMetaRefresh()) {
+      $out = $new;
+    }
+
+    $verbose = 'GET request to: ' . $path .
+               '<hr />Ending URL: ' . $this->getUrl();
+    if ($this->dumpHeaders) {
+      $verbose .= '<hr />Headers: <pre>' . check_plain(var_export(array_map('trim', $this->headers), TRUE)) . '</pre>';
+    }
+    $verbose .= '<hr />' . $out;
+
+    $this->verbose($verbose);
+    return $out;
+  }
+
+  /**
+   * Retrieves a Drupal path or an absolute path and JSON decode the result.
+   *
+   * @param string $path
+   *   Path to request AJAX from.
+   * @param array $options
+   *   Array of options to pass to url().
+   * @param array $headers
+   *   Array of headers. Eg array('Accept: application/vnd.drupal-ajax').
+   *
+   * @return array
+   *   Decoded json.
+   * Requests a Drupal path in JSON format, and JSON decodes the response.
+   */
+  protected function drupalGetJSON($path, array $options = array(), array $headers = array()) {
+    $headers[] = 'Accept: application/json';
+    return drupal_json_decode($this->drupalGet($path, $options, $headers));
+  }
+
+  /**
+   * Requests a Drupal path in drupal_ajax format and JSON-decodes the response.
+   */
+  protected function drupalGetAJAX($path, array $options = array(), array $headers = array()) {
+    $headers[] = 'Accept: application/vnd.drupal-ajax';
+    return drupal_json_decode($this->drupalGet($path, $options, $headers));
+  }
+
+  /**
+   * Executes a form submission.
+   *
+   * It will be done as usual POST request with SimpleBrowser.
+   *
+   * @param $path
+   *   Location of the post form. Either a Drupal path or an absolute path or
+   *   NULL to post to the current page. For multi-stage forms you can set the
+   *   path to NULL and have it post to the last received page. Example:
+   *
+   *   @code
+   *   // First step in form.
+   *   $edit = array(...);
+   *   $this->drupalPostForm('some_url', $edit, t('Save'));
+   *
+   *   // Second step in form.
+   *   $edit = array(...);
+   *   $this->drupalPostForm(NULL, $edit, t('Save'));
+   *   @endcode
+   * @param  $edit
+   *   Field data in an associative array. Changes the current input fields
+   *   (where possible) to the values indicated.
+   *
+   *   When working with form tests, the keys for an $edit element should match
+   *   the 'name' parameter of the HTML of the form. For example, the 'body'
+   *   field for a node has the following HTML:
+   *   @code
+   *   <textarea id="edit-body-und-0-value" class="text-full form-textarea
+   *    resize-vertical" placeholder="" cols="60" rows="9"
+   *    name="body[0][value]"></textarea>
+   *   @endcode
+   *   When testing this field using an $edit parameter, the code becomes:
+   *   @code
+   *   $edit["body[0][value]"] = 'My test value';
+   *   @endcode
+   *
+   *   A checkbox can be set to TRUE to be checked and should be set to FALSE to
+   *   be unchecked. Multiple select fields can be tested using 'name[]' and
+   *   setting each of the desired values in an array:
+   *   @code
+   *   $edit = array();
+   *   $edit['name[]'] = array('value1', 'value2');
+   *   @endcode
+   *
+   *   Note that when a form contains file upload fields, other
+   *   fields cannot start with the '@' character.
+   * @param $submit
+   *   Value of the submit button whose click is to be emulated. For example,
+   *   t('Save'). The processing of the request depends on this value. For
+   *   example, a form may have one button with the value t('Save') and another
+   *   button with the value t('Delete'), and execute different code depending
+   *   on which one is clicked.
+   *
+   *   This function can also be called to emulate an Ajax submission. In this
+   *   case, this value needs to be an array with the following keys:
+   *   - path: A path to submit the form values to for Ajax-specific processing,
+   *     which is likely different than the $path parameter used for retrieving
+   *     the initial form. Defaults to 'system/ajax'.
+   *   - triggering_element: If the value for the 'path' key is 'system/ajax' or
+   *     another generic Ajax processing path, this needs to be set to the name
+   *     of the element. If the name doesn't identify the element uniquely, then
+   *     this should instead be an array with a single key/value pair,
+   *     corresponding to the element name and value. The callback for the
+   *     generic Ajax processing path uses this to find the #ajax information
+   *     for the element, including which specific callback to use for
+   *     processing the request.
+   *
+   *   This can also be set to NULL in order to emulate an Internet Explorer
+   *   submission of a form with a single text field, and pressing ENTER in that
+   *   textfield: under these conditions, no button information is added to the
+   *   POST data.
+   * @param $options
+   *   Options to be forwarded to the url generator.
+   * @param $headers
+   *   An array containing additional HTTP request headers, each formatted as
+   *   "name: value".
+   * @param $form_html_id
+   *   (optional) HTML ID of the form to be submitted. On some pages
+   *   there are many identical forms, so just using the value of the submit
+   *   button is not enough. For example: 'trigger-node-presave-assign-form'.
+   *   Note that this is not the Drupal $form_id, but rather the HTML ID of the
+   *   form, which is typically the same thing but with hyphens replacing the
+   *   underscores.
+   * @param $extra_post
+   *   (optional) A string of additional data to append to the POST submission.
+   *   This can be used to add POST data for which there are no HTML fields, as
+   *   is done by drupalPostAjaxForm(). This string is literally appended to the
+   *   POST data, so it must already be urlencoded and contain a leading "&"
+   *   (e.g., "&extra_var1=hello+world&extra_var2=you%26me").
+   */
+  protected function drupalPostForm($path, $edit, $submit, array $options = array(), array $headers = array(), $form_html_id = NULL, $extra_post = NULL) {
+    $submit_matches = FALSE;
+    $ajax = is_array($submit);
+    if (isset($path)) {
+      $this->drupalGet($path, $options);
+    }
+    if ($this->parse()) {
+      $edit_save = $edit;
+      // Let's iterate over all the forms.
+      $xpath = "//form";
+      if (!empty($form_html_id)) {
+        $xpath .= "[@id='" . $form_html_id . "']";
+      }
+      $forms = $this->xpath($xpath);
+      foreach ($forms as $form) {
+        // We try to set the fields of this form as specified in $edit.
+        $edit = $edit_save;
+        $post = array();
+        $upload = array();
+        $submit_matches = $this->handleForm($post, $edit, $upload, $ajax ? NULL : $submit, $form);
+        $action = isset($form['action']) ? $this->getAbsoluteUrl((string) $form['action']) : $this->getUrl();
+        if ($ajax) {
+          $action = $this->getAbsoluteUrl(!empty($submit['path']) ? $submit['path'] : 'system/ajax');
+          // Ajax callbacks verify the triggering element if necessary, so while
+          // we may eventually want extra code that verifies it in the
+          // handleForm() function, it's not currently a requirement.
+          $submit_matches = TRUE;
+        }
+        // We post only if we managed to handle every field in edit and the
+        // submit button matches.
+        if (!$edit && ($submit_matches || !isset($submit))) {
+          $post_array = $post;
+          if ($upload) {
+            foreach ($upload as $key => $file) {
+              $file = drupal_realpath($file);
+              if ($file && is_file($file)) {
+                // Use the new CurlFile class for file uploads when using PHP
+                // 5.5.
+                if (class_exists('CurlFile')) {
+                  $post[$key] = curl_file_create($file);
+                }
+                else {
+                  // @todo: Drop support for this when PHP 5.5 is required.
+                  $post[$key] = '@' . $file;
+                }
+              }
+            }
+          }
+          else {
+            $post = $this->serializePostValues($post) . $extra_post;
+          }
+          $out = $this->curlExec(array(CURLOPT_URL => $action, CURLOPT_POST => TRUE, CURLOPT_POSTFIELDS => $post, CURLOPT_HTTPHEADER => $headers));
+          // Ensure that any changes to variables in the other thread are picked
+          // up.
+          $this->refreshVariables();
+
+          // Replace original page output with new output from redirected
+          // page(s).
+          if ($new = $this->checkForMetaRefresh()) {
+            $out = $new;
+          }
+
+          $verbose = 'POST request to: ' . $path;
+          $verbose .= '<hr />Ending URL: ' . $this->getUrl();
+          if ($this->dumpHeaders) {
+            $verbose .= '<hr />Headers: <pre>' . check_plain(var_export(array_map('trim', $this->headers), TRUE)) . '</pre>';
+          }
+          $verbose .= '<hr />Fields: ' . highlight_string('<?php ' . var_export($post_array, TRUE), TRUE);
+          $verbose .= '<hr />' . $out;
+
+          $this->verbose($verbose);
+          return $out;
+        }
+      }
+      // We have not found a form which contained all fields of $edit.
+      foreach ($edit as $name => $value) {
+        $this->fail(t('Failed to set field @name to @value', array('@name' => $name, '@value' => $value)));
+      }
+      if (!$ajax && isset($submit)) {
+        $this->assertTrue($submit_matches, format_string('Found the @submit button', array('@submit' => $submit)));
+      }
+      $this->fail(format_string('Found the requested form fields at @path', array('@path' => $path)));
+    }
+  }
+
+  /**
+   * Executes an Ajax form submission.
+   *
+   * This executes a POST as ajax.js does. The returned JSON data is used to
+   * update $this->content via drupalProcessAjaxResponse(). It also returns
+   * the array of AJAX commands received.
+   *
+   * @param $path
+   *   Location of the form containing the Ajax enabled element to test. Can be
+   *   either a Drupal path or an absolute path or NULL to use the current page.
+   * @param $edit
+   *   Field data in an associative array. Changes the current input fields
+   *   (where possible) to the values indicated.
+   * @param $triggering_element
+   *   The name of the form element that is responsible for triggering the Ajax
+   *   functionality to test. May be a string or, if the triggering element is
+   *   a button, an associative array where the key is the name of the button
+   *   and the value is the button label. i.e.) array('op' => t('Refresh')).
+   * @param $ajax_path
+   *   (optional) Override the path set by the Ajax settings of the triggering
+   *   element. In the absence of both the triggering element's Ajax path and
+   *   $ajax_path 'system/ajax' will be used.
+   * @param $options
+   *   (optional) Options to be forwarded to the url generator.
+   * @param $headers
+   *   (optional) An array containing additional HTTP request headers, each
+   *   formatted as "name: value". Forwarded to drupalPostForm().
+   * @param $form_html_id
+   *   (optional) HTML ID of the form to be submitted, use when there is more
+   *   than one identical form on the same page and the value of the triggering
+   *   element is not enough to identify the form. Note this is not the Drupal
+   *   ID of the form but rather the HTML ID of the form.
+   * @param $ajax_settings
+   *   (optional) An array of Ajax settings which if specified will be used in
+   *   place of the Ajax settings of the triggering element.
+   *
+   * @return
+   *   An array of Ajax commands.
+   *
+   * @see drupalPostForm()
+   * @see drupalProcessAjaxResponse()
+   * @see ajax.js
+   */
+  protected function drupalPostAjaxForm($path, $edit, $triggering_element, $ajax_path = NULL, array $options = array(), array $headers = array(), $form_html_id = NULL, $ajax_settings = NULL) {
+    // Get the content of the initial page prior to calling drupalPostForm(),
+    // since drupalPostForm() replaces $this->content.
+    if (isset($path)) {
+      $this->drupalGet($path, $options);
+    }
+    $content = $this->content;
+    $drupal_settings = $this->drupalSettings;
+
+    $headers[] = 'Accept: application/vnd.drupal-ajax';
+
+    // Get the Ajax settings bound to the triggering element.
+    if (!isset($ajax_settings)) {
+      if (is_array($triggering_element)) {
+        $xpath = '//*[@name="' . key($triggering_element) . '" and @value="' . current($triggering_element) . '"]';
+      }
+      else {
+        $xpath = '//*[@name="' . $triggering_element . '"]';
+      }
+      if (isset($form_html_id)) {
+        $xpath = '//form[@id="' . $form_html_id . '"]' . $xpath;
+      }
+      $element = $this->xpath($xpath);
+      $element_id = (string) $element[0]['id'];
+      $ajax_settings = $drupal_settings['ajax'][$element_id];
+    }
+
+    // Add extra information to the POST data as ajax.js does.
+    $extra_post = array();
+    if (isset($ajax_settings['submit'])) {
+      foreach ($ajax_settings['submit'] as $key => $value) {
+        $extra_post[$key] = $value;
+      }
+    }
+    $ajax_html_ids = array();
+    foreach ($this->xpath('//*[@id]') as $element) {
+      $ajax_html_ids[] = (string) $element['id'];
+    }
+    if (!empty($ajax_html_ids)) {
+      $extra_post['ajax_html_ids'] = implode(' ', $ajax_html_ids);
+    }
+    $extra_post += $this->getAjaxPageStatePostData();
+    // Now serialize all the $extra_post values, and prepend it with an '&'.
+    $extra_post = '&' . $this->serializePostValues($extra_post);
+
+    // Unless a particular path is specified, use the one specified by the
+    // Ajax settings, or else 'system/ajax'.
+    if (!isset($ajax_path)) {
+      $ajax_path = isset($ajax_settings['url']) ? $ajax_settings['url'] : 'system/ajax';
+    }
+
+    // Submit the POST request.
+    $return = drupal_json_decode($this->drupalPostForm(NULL, $edit, array('path' => $ajax_path, 'triggering_element' => $triggering_element), $options, $headers, $form_html_id, $extra_post));
+
+    // Change the page content by applying the returned commands.
+    if (!empty($ajax_settings) && !empty($return)) {
+      $this->drupalProcessAjaxResponse($content, $return, $ajax_settings, $drupal_settings);
+    }
+
+    return $return;
+  }
+
+  /**
+   * Processes an AJAX response into current content.
+   *
+   * This processes the AJAX response as ajax.js does. It uses the response's
+   * JSON data, an array of commands, to update $this->content using equivalent
+   * DOM manipulation as is used by ajax.js.
+   * It does not apply custom AJAX commands though, because emulation is only
+   * implemented for the AJAX commands that ship with Drupal core.
+   *
+   * @param string $content
+   *   The current HTML content.
+   * @param array $ajax_response
+   *   An array of AJAX commands.
+   * @param array $ajax_settings
+   *   An array of AJAX settings which will be used to process the response.
+   * @param array $drupal_settings
+   *   An array of settings to update the value of drupalSettings for the
+   *   currently-loaded page.
+   *
+   * @see drupalPostAjaxForm()
+   * @see ajax.js
+   */
+  protected function drupalProcessAjaxResponse($content, array $ajax_response, array $ajax_settings, array $drupal_settings) {
+
+    // ajax.js applies some defaults to the settings object, so do the same
+    // for what's used by this function.
+    $ajax_settings += array(
+      'method' => 'replaceWith',
+    );
+    // DOM can load HTML soup. But, HTML soup can throw warnings, suppress
+    // them.
+    $dom = new \DOMDocument();
+    @$dom->loadHTML($content);
+    // XPath allows for finding wrapper nodes better than DOM does.
+    $xpath = new \DOMXPath($dom);
+    foreach ($ajax_response as $command) {
+      switch ($command['command']) {
+        case 'settings':
+          $drupal_settings = drupal_merge_js_settings(array($drupal_settings, $command['settings']));
+          break;
+
+        case 'insert':
+          $wrapperNode = NULL;
+          // When a command doesn't specify a selector, use the
+          // #ajax['wrapper'] which is always an HTML ID.
+          if (!isset($command['selector'])) {
+            $wrapperNode = $xpath->query('//*[@id="' . $ajax_settings['wrapper'] . '"]')->item(0);
+          }
+          // @todo Ajax commands can target any jQuery selector, but these are
+          //   hard to fully emulate with XPath. For now, just handle 'head'
+          //   and 'body', since these are used by ajax_render().
+          elseif (in_array($command['selector'], array('head', 'body'))) {
+            $wrapperNode = $xpath->query('//' . $command['selector'])->item(0);
+          }
+          if ($wrapperNode) {
+            // ajax.js adds an enclosing DIV to work around a Safari bug.
+            $newDom = new \DOMDocument();
+            @$newDom->loadHTML('<div>' . $command['data'] . '</div>');
+            $newNode = $dom->importNode($newDom->documentElement->firstChild->firstChild, TRUE);
+            $method = isset($command['method']) ? $command['method'] : $ajax_settings['method'];
+            // The "method" is a jQuery DOM manipulation function. Emulate
+            // each one using PHP's DOMNode API.
+            switch ($method) {
+              case 'replaceWith':
+                $wrapperNode->parentNode->replaceChild($newNode, $wrapperNode);
+                break;
+              case 'append':
+                $wrapperNode->appendChild($newNode);
+                break;
+              case 'prepend':
+                // If no firstChild, insertBefore() falls back to
+                // appendChild().
+                $wrapperNode->insertBefore($newNode, $wrapperNode->firstChild);
+                break;
+              case 'before':
+                $wrapperNode->parentNode->insertBefore($newNode, $wrapperNode);
+                break;
+              case 'after':
+                // If no nextSibling, insertBefore() falls back to
+                // appendChild().
+                $wrapperNode->parentNode->insertBefore($newNode, $wrapperNode->nextSibling);
+                break;
+              case 'html':
+                foreach ($wrapperNode->childNodes as $childNode) {
+                  $wrapperNode->removeChild($childNode);
+                }
+                $wrapperNode->appendChild($newNode);
+                break;
+            }
+          }
+          break;
+
+        // @todo Add suitable implementations for these commands in order to
+        //   have full test coverage of what ajax.js can do.
+        case 'remove':
+          break;
+        case 'changed':
+          break;
+        case 'css':
+          break;
+        case 'data':
+          break;
+        case 'restripe':
+          break;
+        case 'add_css':
+          break;
+      }
+    }
+    $content = $dom->saveHTML();
+    $this->drupalSetContent($content);
+    $this->drupalSetSettings($drupal_settings);
+  }
+
+  /**
+   * Perform a POST HTTP request.
+   *
+   * @param string $path
+   *   Drupal path where the request should be POSTed to. Will be transformed
+   *   into an absolute path automatically.
+   * @param string $accept
+   *   The value for the "Accept" header. Usually either 'application/json' or
+   *   'application/vnd.drupal-ajax'.
+   * @param array $post
+   *   The POST data. When making a 'application/vnd.drupal-ajax' request, the
+   *   Ajax page state data should be included. Use getAjaxPageStatePostData()
+   *   for that.
+   * @param array $options
+   *   (optional) Options to be forwarded to the url generator. The 'absolute'
+   *   option will automatically be enabled.
+   *
+   * @return
+   *   The content returned from the call to curl_exec().
+   *
+   * @see WebTestBase::getAjaxPageStatePostData()
+   * @see WebTestBase::curlExec()
+   * @see url()
+   */
+  protected function drupalPost($path, $accept, array $post, $options = array()) {
+    return $this->curlExec(array(
+      CURLOPT_URL => url($path, $options + array('absolute' => TRUE)),
+      CURLOPT_POST => TRUE,
+      CURLOPT_POSTFIELDS => $this->serializePostValues($post),
+      CURLOPT_HTTPHEADER => array(
+        'Accept: ' . $accept,
+        'Content-Type: application/x-www-form-urlencoded',
+      ),
+    ));
+  }
+
+  /**
+   * Get server-rendered contextual links for the given contextual link ids.
+   *
+   * Requires that contextual.module is enabled to work correctly.
+   *
+   * @param array $ids
+   *   An array of contextual link ids.
+   * @param string $current_path
+   *   The Drupal path for the page for which the contextual links are rendered.
+   *
+   * @return string
+   *   The response body.
+   */
+  protected function renderContextualLinks($ids, $current_path) {
+    $post = array();
+    for ($i = 0; $i < count($ids); $i++) {
+      $post['ids[' . $i . ']'] = $ids[$i];
+    }
+    return $this->drupalPost('contextual/render', 'application/json', $post, array('query' => array('destination' => $current_path)));
+  }
+
+  /**
+   * Get the Ajax page state from drupalSettings and prepare it for POSTing.
+   *
+   * @return array
+   *   The Ajax page state POST data.
+   */
+  protected function getAjaxPageStatePostData() {
+    $post = array();
+    $drupal_settings = $this->drupalSettings;
+    if (isset($drupal_settings['ajaxPageState'])) {
+      $post['ajax_page_state[theme]'] = $drupal_settings['ajaxPageState']['theme'];
+      $post['ajax_page_state[theme_token]'] = $drupal_settings['ajaxPageState']['theme_token'];
+      foreach ($drupal_settings['ajaxPageState']['css'] as $key => $value) {
+        $post["ajax_page_state[css][$key]"] = 1;
+      }
+      foreach ($drupal_settings['ajaxPageState']['js'] as $key => $value) {
+        $post["ajax_page_state[js][$key]"] = 1;
+      }
+    }
+    return $post;
+  }
+
+  /**
+   * Serialize POST HTTP request values.
+   *
+   * Encode according to application/x-www-form-urlencoded. Both names and
+   * values needs to be urlencoded, according to
+   * http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.1
+   *
+   * @param array $post
+   *   The array of values to be POSTed.
+   *
+   * @return string
+   *   The serialized result.
+   */
+  protected function serializePostValues($post = array()) {
+    foreach ($post as $key => $value) {
+      $post[$key] = urlencode($key) . '=' . urlencode($value);
+    }
+    return implode('&', $post);
+  }
+
+  /**
+   * Runs cron in the Drupal installed by Simpletest.
+   */
+  protected function cronRun() {
+    $this->drupalGet('cron/' . \Drupal::state()->get('system.cron_key'));
+  }
+
+  /**
+   * Checks for meta refresh tag and if found call drupalGet() recursively.
+   *
+   * This function looks for the http-equiv attribute to be set to "Refresh" and
+   * is case-sensitive.
+   *
+   * @return
+   *   Either the new page content or FALSE.
+   */
+  protected function checkForMetaRefresh() {
+    if (strpos($this->drupalGetContent(), '<meta ') && $this->parse()) {
+      $refresh = $this->xpath('//meta[@http-equiv="Refresh"]');
+      if (!empty($refresh)) {
+        // Parse the content attribute of the meta tag for the format:
+        // "[delay]: URL=[page_to_redirect_to]".
+        if (preg_match('/\d+;\s*URL=(?<url>.*)/i', $refresh[0]['content'], $match)) {
+          return $this->drupalGet($this->getAbsoluteUrl(decode_entities($match['url'])));
+        }
+      }
+    }
+    return FALSE;
+  }
+
+  /**
+   * Retrieves only the headers for a Drupal path or an absolute path.
+   *
+   * @param $path
+   *   Drupal path or URL to load into internal browser
+   * @param $options
+   *   Options to be forwarded to the url generator.
+   * @param $headers
+   *   An array containing additional HTTP request headers, each formatted as
+   *   "name: value".
+   *
+   * @return
+   *   The retrieved headers, also available as $this->drupalGetContent()
+   */
+  protected function drupalHead($path, array $options = array(), array $headers = array()) {
+    $options['absolute'] = TRUE;
+    $url = $this->container->get('url_generator')->generateFromPath($path, $options);
+    $out = $this->curlExec(array(CURLOPT_NOBODY => TRUE, CURLOPT_URL => $url, CURLOPT_HTTPHEADER => $headers));
+    // Ensure that any changes to variables in the other thread are picked up.
+    $this->refreshVariables();
+
+    if ($this->dumpHeaders) {
+      $this->verbose('GET request to: ' . $path .
+                     '<hr />Ending URL: ' . $this->getUrl() .
+                     '<hr />Headers: <pre>' . check_plain(var_export(array_map('trim', $this->headers), TRUE)) . '</pre>');
+    }
+
+    return $out;
+  }
+
+  /**
+   * Handles form input related to drupalPostForm().
+   *
+   * Ensure that the specified fields exist and attempt to create POST data in
+   * the correct manner for the particular field type.
+   *
+   * @param $post
+   *   Reference to array of post values.
+   * @param $edit
+   *   Reference to array of edit values to be checked against the form.
+   * @param $submit
+   *   Form submit button value.
+   * @param $form
+   *   Array of form elements.
+   *
+   * @return
+   *   Submit value matches a valid submit input in the form.
+   */
+  protected function handleForm(&$post, &$edit, &$upload, $submit, $form) {
+    // Retrieve the form elements.
+    $elements = $form->xpath('.//input[not(@disabled)]|.//textarea[not(@disabled)]|.//select[not(@disabled)]');
+    $submit_matches = FALSE;
+    foreach ($elements as $element) {
+      // SimpleXML objects need string casting all the time.
+      $name = (string) $element['name'];
+      // This can either be the type of <input> or the name of the tag itself
+      // for <select> or <textarea>.
+      $type = isset($element['type']) ? (string) $element['type'] : $element->getName();
+      $value = isset($element['value']) ? (string) $element['value'] : '';
+      $done = FALSE;
+      if (isset($edit[$name])) {
+        switch ($type) {
+          case 'text':
+          case 'tel':
+          case 'textarea':
+          case 'url':
+          case 'number':
+          case 'range':
+          case 'color':
+          case 'hidden':
+          case 'password':
+          case 'email':
+          case 'search':
+          case 'date':
+          case 'time':
+          case 'datetime':
+          case 'datetime-local';
+            $post[$name] = $edit[$name];
+            unset($edit[$name]);
+            break;
+          case 'radio':
+            if ($edit[$name] == $value) {
+              $post[$name] = $edit[$name];
+              unset($edit[$name]);
+            }
+            break;
+          case 'checkbox':
+            // To prevent checkbox from being checked.pass in a FALSE,
+            // otherwise the checkbox will be set to its value regardless
+            // of $edit.
+            if ($edit[$name] === FALSE) {
+              unset($edit[$name]);
+              continue 2;
+            }
+            else {
+              unset($edit[$name]);
+              $post[$name] = $value;
+            }
+            break;
+          case 'select':
+            $new_value = $edit[$name];
+            $options = $this->getAllOptions($element);
+            if (is_array($new_value)) {
+              // Multiple select box.
+              if (!empty($new_value)) {
+                $index = 0;
+                $key = preg_replace('/\[\]$/', '', $name);
+                foreach ($options as $option) {
+                  $option_value = (string) $option['value'];
+                  if (in_array($option_value, $new_value)) {
+                    $post[$key . '[' . $index++ . ']'] = $option_value;
+                    $done = TRUE;
+                    unset($edit[$name]);
+                  }
+                }
+              }
+              else {
+                // No options selected: do not include any POST data for the
+                // element.
+                $done = TRUE;
+                unset($edit[$name]);
+              }
+            }
+            else {
+              // Single select box.
+              foreach ($options as $option) {
+                if ($new_value == $option['value']) {
+                  $post[$name] = $new_value;
+                  unset($edit[$name]);
+                  $done = TRUE;
+                  break;
+                }
+              }
+            }
+            break;
+          case 'file':
+            $upload[$name] = $edit[$name];
+            unset($edit[$name]);
+            break;
+        }
+      }
+      if (!isset($post[$name]) && !$done) {
+        switch ($type) {
+          case 'textarea':
+            $post[$name] = (string) $element;
+            break;
+          case 'select':
+            $single = empty($element['multiple']);
+            $first = TRUE;
+            $index = 0;
+            $key = preg_replace('/\[\]$/', '', $name);
+            $options = $this->getAllOptions($element);
+            foreach ($options as $option) {
+              // For single select, we load the first option, if there is a
+              // selected option that will overwrite it later.
+              if ($option['selected'] || ($first && $single)) {
+                $first = FALSE;
+                if ($single) {
+                  $post[$name] = (string) $option['value'];
+                }
+                else {
+                  $post[$key . '[' . $index++ . ']'] = (string) $option['value'];
+                }
+              }
+            }
+            break;
+          case 'file':
+            break;
+          case 'submit':
+          case 'image':
+            if (isset($submit) && $submit == $value) {
+              $post[$name] = $value;
+              $submit_matches = TRUE;
+            }
+            break;
+          case 'radio':
+          case 'checkbox':
+            if (!isset($element['checked'])) {
+              break;
+            }
+            // Deliberate no break.
+          default:
+            $post[$name] = $value;
+        }
+      }
+    }
+    return $submit_matches;
+  }
+
+  /**
+   * Builds an XPath query.
+   *
+   * Builds an XPath query by replacing placeholders in the query by the value
+   * of the arguments.
+   *
+   * XPath 1.0 (the version supported by libxml2, the underlying XML library
+   * used by PHP) doesn't support any form of quotation. This function
+   * simplifies the building of XPath expression.
+   *
+   * @param $xpath
+   *   An XPath query, possibly with placeholders in the form ':name'.
+   * @param $args
+   *   An array of arguments with keys in the form ':name' matching the
+   *   placeholders in the query. The values may be either strings or numeric
+   *   values.
+   *
+   * @return
+   *   An XPath query with arguments replaced.
+   */
+  protected function buildXPathQuery($xpath, array $args = array()) {
+    // Replace placeholders.
+    foreach ($args as $placeholder => $value) {
+      // XPath 1.0 doesn't support a way to escape single or double quotes in a
+      // string literal. We split double quotes out of the string, and encode
+      // them separately.
+      if (is_string($value)) {
+        // Explode the text at the quote characters.
+        $parts = explode('"', $value);
+
+        // Quote the parts.
+        foreach ($parts as &$part) {
+          $part = '"' . $part . '"';
+        }
+
+        // Return the string.
+        $value = count($parts) > 1 ? 'concat(' . implode(', \'"\', ', $parts) . ')' : $parts[0];
+      }
+
+      // Use preg_replace_callback() instead of preg_replace() to prevent the
+      // regular expression engine from trying to substitute backreferences.
+      $replacement = function ($matches) use ($value) {
+        return $value;
+      };
+      $xpath = preg_replace_callback('/' . preg_quote($placeholder) . '\b/', $replacement, $xpath);
+    }
+    return $xpath;
+  }
+
+  /**
+   * Performs an xpath search on the contents of the internal browser.
+   *
+   * The search is relative to the root element (HTML tag normally) of the page.
+   *
+   * @param $xpath
+   *   The xpath string to use in the search.
+   *
+   * @return
+   *   The return value of the xpath search. For details on the xpath string
+   *   format and return values see the SimpleXML documentation,
+   *   http://php.net/manual/function.simplexml-element-xpath.php.
+   */
+  protected function xpath($xpath, array $arguments = array()) {
+    if ($this->parse()) {
+      $xpath = $this->buildXPathQuery($xpath, $arguments);
+      $result = $this->elements->xpath($xpath);
+      // Some combinations of PHP / libxml versions return an empty array
+      // instead of the documented FALSE. Forcefully convert any falsish values
+      // to an empty array to allow foreach(...) constructions.
+      return $result ? $result : array();
+    }
+    else {
+      return FALSE;
+    }
+  }
+
+  /**
+   * Get all option elements, including nested options, in a select.
+   *
+   * @param $element
+   *   The element for which to get the options.
+   *
+   * @return
+   *   Option elements in select.
+   */
+  protected function getAllOptions(\SimpleXMLElement $element) {
+    $options = array();
+    // Add all options items.
+    foreach ($element->option as $option) {
+      $options[] = $option;
+    }
+
+    // Search option group children.
+    if (isset($element->optgroup)) {
+      foreach ($element->optgroup as $group) {
+        $options = array_merge($options, $this->getAllOptions($group));
+      }
+    }
+    return $options;
+  }
+
+  /**
+   * Passes if a link with the specified label is found.
+   *
+   * An optional link index may be passed.
+   *
+   * @param $label
+   *   Text between the anchor tags.
+   * @param $index
+   *   Link position counting from zero.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The gorup this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE if the assertion succeeded, FALSE otherwise.
+   */
+  protected function assertLink($label, $index = 0, $message = '', $group = 'Other') {
+    $links = $this->xpath('//a[normalize-space(text())=:label]', array(':label' => $label));
+    $message = ($message ?  $message : t('Link with label %label found.', array('%label' => $label)));
+    return $this->assert(isset($links[$index]), $message, $group);
+  }
+
+  /**
+   * Passes if a link with the specified label is not found.
+   *
+   * @param $label
+   *   Text between the anchor tags.
+   * @param $index
+   *   Link position counting from zero.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE if the assertion succeeded, FALSE otherwise.
+   */
+  protected function assertNoLink($label, $message = '', $group = 'Other') {
+    $links = $this->xpath('//a[normalize-space(text())=:label]', array(':label' => $label));
+    $message = ($message ?  $message : t('Link with label %label not found.', array('%label' => $label)));
+    return $this->assert(empty($links), $message, $group);
+  }
+
+  /**
+   * Passes if a link containing a given href (part) is found.
+   *
+   * @param $href
+   *   The full or partial value of the 'href' attribute of the anchor tag.
+   * @param $index
+   *   Link position counting from zero.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE if the assertion succeeded, FALSE otherwise.
+   */
+  protected function assertLinkByHref($href, $index = 0, $message = '', $group = 'Other') {
+    $links = $this->xpath('//a[contains(@href, :href)]', array(':href' => $href));
+    $message = ($message ?  $message : t('Link containing href %href found.', array('%href' => $href)));
+    return $this->assert(isset($links[$index]), $message, $group);
+  }
+
+  /**
+   * Passes if a link containing a given href (part) is not found.
+   *
+   * @param $href
+   *   The full or partial value of the 'href' attribute of the anchor tag.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE if the assertion succeeded, FALSE otherwise.
+   */
+  protected function assertNoLinkByHref($href, $message = '', $group = 'Other') {
+    $links = $this->xpath('//a[contains(@href, :href)]', array(':href' => $href));
+    $message = ($message ?  $message : t('No link containing href %href found.', array('%href' => $href)));
+    return $this->assert(empty($links), $message, $group);
+  }
+
+  /**
+   * Follows a link by name.
+   *
+   * Will click the first link found with this link text by default, or a later
+   * one if an index is given. Match is case sensitive with normalized space.
+   * The label is translated label. There is an assert for successful click.
+   *
+   * @param $label
+   *   Text between the anchor tags.
+   * @param $index
+   *   Link position counting from zero.
+   *
+   * @return
+   *   Page on success, or FALSE on failure.
+   */
+  protected function clickLink($label, $index = 0) {
+    $url_before = $this->getUrl();
+    $urls = $this->xpath('//a[normalize-space(text())=:label]', array(':label' => $label));
+
+    if (isset($urls[$index])) {
+      $url_target = $this->getAbsoluteUrl($urls[$index]['href']);
+    }
+
+    $this->assertTrue(isset($urls[$index]), String::format('Clicked link %label (@url_target) from @url_before', array('%label' => $label, '@url_target' => $url_target, '@url_before' => $url_before)), 'Browser');
+
+    if (isset($url_target)) {
+      return $this->drupalGet($url_target);
+    }
+    return FALSE;
+  }
+
+  /**
+   * Takes a path and returns an absolute path.
+   *
+   * @param $path
+   *   A path from the internal browser content.
+   *
+   * @return
+   *   The $path with $base_url prepended, if necessary.
+   */
+  protected function getAbsoluteUrl($path) {
+    global $base_url, $base_path;
+
+    $parts = parse_url($path);
+    if (empty($parts['host'])) {
+      // Ensure that we have a string (and no xpath object).
+      $path = (string) $path;
+      // Strip $base_path, if existent.
+      $length = strlen($base_path);
+      if (substr($path, 0, $length) === $base_path) {
+        $path = substr($path, $length);
+      }
+      // Ensure that we have an absolute path.
+      if ($path[0] !== '/') {
+        $path = '/' . $path;
+      }
+      // Finally, prepend the $base_url.
+      $path = $base_url . $path;
+    }
+    return $path;
+  }
+
+  /**
+   * Get the current URL from the cURL handler.
+   *
+   * @return
+   *   The current URL.
+   */
+  protected function getUrl() {
+    return $this->url;
+  }
+
+  /**
+   * Gets the HTTP response headers of the requested page.
+   *
+   * Normally we are only interested in the headers returned by the last
+   * request. However, if a page is redirected or HTTP authentication is in use,
+   * multiple requests will be required to retrieve the page. Headers from all
+   * requests may be requested by passing TRUE to this function.
+   *
+   * @param $all_requests
+   *   Boolean value specifying whether to return headers from all requests
+   *   instead of just the last request. Defaults to FALSE.
+   *
+   * @return
+   *   A name/value array if headers from only the last request are requested.
+   *   If headers from all requests are requested, an array of name/value
+   *   arrays, one for each request.
+   *
+   *   The pseudonym ":status" is used for the HTTP status line.
+   *
+   *   Values for duplicate headers are stored as a single comma-separated list.
+   */
+  protected function drupalGetHeaders($all_requests = FALSE) {
+    $request = 0;
+    $headers = array($request => array());
+    foreach ($this->headers as $header) {
+      $header = trim($header);
+      if ($header === '') {
+        $request++;
+      }
+      else {
+        if (strpos($header, 'HTTP/') === 0) {
+          $name = ':status';
+          $value = $header;
+        }
+        else {
+          list($name, $value) = explode(':', $header, 2);
+          $name = strtolower($name);
+        }
+        if (isset($headers[$request][$name])) {
+          $headers[$request][$name] .= ',' . trim($value);
+        }
+        else {
+          $headers[$request][$name] = trim($value);
+        }
+      }
+    }
+    if (!$all_requests) {
+      $headers = array_pop($headers);
+    }
+    return $headers;
+  }
+
+  /**
+   * Gets the value of an HTTP response header.
+   *
+   * If multiple requests were required to retrieve the page, only the headers
+   * from the last request will be checked by default. However, if TRUE is
+   * passed as the second argument, all requests will be processed from last to
+   * first until the header is found.
+   *
+   * @param $name
+   *   The name of the header to retrieve. Names are case-insensitive (see RFC
+   *   2616 section 4.2).
+   * @param $all_requests
+   *   Boolean value specifying whether to check all requests if the header is
+   *   not found in the last request. Defaults to FALSE.
+   *
+   * @return
+   *   The HTTP header value or FALSE if not found.
+   */
+  protected function drupalGetHeader($name, $all_requests = FALSE) {
+    $name = strtolower($name);
+    $header = FALSE;
+    if ($all_requests) {
+      foreach (array_reverse($this->drupalGetHeaders(TRUE)) as $headers) {
+        if (isset($headers[$name])) {
+          $header = $headers[$name];
+          break;
+        }
+      }
+    }
+    else {
+      $headers = $this->drupalGetHeaders();
+      if (isset($headers[$name])) {
+        $header = $headers[$name];
+      }
+    }
+    return $header;
+  }
+
+  /**
+   * Gets the current raw HTML of requested page.
+   */
+  protected function drupalGetContent() {
+    return $this->content;
+  }
+
+  /**
+   * Gets the value of drupalSettings for the currently-loaded page.
+   *
+   * drupalSettings refers to the drupalSettings JavaScript variable.
+   */
+  protected function drupalGetSettings() {
+    return $this->drupalSettings;
+  }
+
+  /**
+   * Gets an array containing all e-mails sent during this test case.
+   *
+   * @param $filter
+   *   An array containing key/value pairs used to filter the e-mails that are
+   *   returned.
+   *
+   * @return
+   *   An array containing e-mail messages captured during the current test.
+   */
+  protected function drupalGetMails($filter = array()) {
+    $captured_emails = \Drupal::state()->get('system.test_email_collector') ?: array();
+    $filtered_emails = array();
+
+    foreach ($captured_emails as $message) {
+      foreach ($filter as $key => $value) {
+        if (!isset($message[$key]) || $message[$key] != $value) {
+          continue 2;
+        }
+      }
+      $filtered_emails[] = $message;
+    }
+
+    return $filtered_emails;
+  }
+
+  /**
+   * Sets the raw HTML content.
+   *
+   * This can be useful when a page has been fetched outside of the internal
+   * browser and assertions need to be made on the returned page.
+   *
+   * A good example would be when testing HTTP request made by Drupal. After
+   * fetching the page the content can be set and page elements can be checked
+   * to ensure that the function worked properly.
+   */
+  protected function drupalSetContent($content, $url = 'internal:') {
+    $this->content = $content;
+    $this->url = $url;
+    $this->plainTextContent = FALSE;
+    $this->elements = FALSE;
+    $this->drupalSettings = array();
+    if (preg_match('/var drupalSettings = (.*?);$/m', $content, $matches)) {
+      $this->drupalSettings = drupal_json_decode($matches[1]);
+    }
+  }
+
+  /**
+   * Sets the value of drupalSettings for the currently-loaded page.
+   *
+   * drupalSettings refers to the drupalSettings JavaScript variable.
+   */
+  protected function drupalSetSettings($settings) {
+    $this->drupalSettings = $settings;
+  }
+
+  /**
+   * Passes if the internal browser's URL matches the given path.
+   *
+   * @param $path
+   *   The expected system path.
+   * @param $options
+   *   (optional) Any additional options to pass for $path to the url generator.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertUrl($path, array $options = array(), $message = '', $group = 'Other') {
+    if (!$message) {
+      $message = t('Current URL is @url.', array(
+        '@url' => var_export($this->container->get('url_generator')->generateFromPath($path, $options), TRUE),
+      ));
+    }
+    $options['absolute'] = TRUE;
+    // Paths in query strings can be encoded or decoded with no functional
+    // difference, decode them for comparison purposes.
+    $actual_url = urldecode($this->getUrl());
+    $expected_url = urldecode($this->container->get('url_generator')->generateFromPath($path, $options));
+    return $this->assertEqual($actual_url, $expected_url, $message, $group);
+  }
+
+  /**
+   * Passes if the raw text IS found on the loaded page, fail otherwise.
+   *
+   * Raw text refers to the raw HTML that the page generated.
+   *
+   * @param $raw
+   *   Raw (HTML) string to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertRaw($raw, $message = '', $group = 'Other') {
+    if (!$message) {
+      $message = t('Raw "@raw" found', array('@raw' => $raw));
+    }
+    return $this->assert(strpos($this->drupalGetContent(), $raw) !== FALSE, $message, $group);
+  }
+
+  /**
+   * Passes if the raw text is NOT found on the loaded page, fail otherwise.
+   *
+   * Raw text refers to the raw HTML that the page generated.
+   *
+   * @param $raw
+   *   Raw (HTML) string to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoRaw($raw, $message = '', $group = 'Other') {
+    if (!$message) {
+      $message = t('Raw "@raw" not found', array('@raw' => $raw));
+    }
+    return $this->assert(strpos($this->drupalGetContent(), $raw) === FALSE, $message, $group);
+  }
+
+  /**
+   * Passes if the text IS found on the text version of the page.
+   *
+   * The text version is the equivalent of what a user would see when viewing
+   * through a web browser. In other words the HTML has been filtered out of the
+   * contents.
+   *
+   * @param $text
+   *   Plain text to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertText($text, $message = '', $group = 'Other') {
+    return $this->assertTextHelper($text, $message, $group, FALSE);
+  }
+
+  /**
+   * Passes if the text is NOT found on the text version of the page.
+   *
+   * The text version is the equivalent of what a user would see when viewing
+   * through a web browser. In other words the HTML has been filtered out of the
+   * contents.
+   *
+   * @param $text
+   *   Plain text to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoText($text, $message = '', $group = 'Other') {
+    return $this->assertTextHelper($text, $message, $group, TRUE);
+  }
+
+  /**
+   * Helper for assertText and assertNoText.
+   *
+   * It is not recommended to call this function directly.
+   *
+   * @param $text
+   *   Plain text to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   * @param $not_exists
+   *   TRUE if this text should not exist, FALSE if it should.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertTextHelper($text, $message = '', $group, $not_exists) {
+    if ($this->plainTextContent === FALSE) {
+      $this->plainTextContent = filter_xss($this->drupalGetContent(), array());
+    }
+    if (!$message) {
+      $message = !$not_exists ? t('"@text" found', array('@text' => $text)) : t('"@text" not found', array('@text' => $text));
+    }
+    return $this->assert($not_exists == (strpos($this->plainTextContent, $text) === FALSE), $message, $group);
+  }
+
+  /**
+   * Passes if the text is found ONLY ONCE on the text version of the page.
+   *
+   * The text version is the equivalent of what a user would see when viewing
+   * through a web browser. In other words the HTML has been filtered out of
+   * the contents.
+   *
+   * @param $text
+   *   Plain text to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertUniqueText($text, $message = '', $group = 'Other') {
+    return $this->assertUniqueTextHelper($text, $message, $group, TRUE);
+  }
+
+  /**
+   * Passes if the text is found MORE THAN ONCE on the text version of the page.
+   *
+   * The text version is the equivalent of what a user would see when viewing
+   * through a web browser. In other words the HTML has been filtered out of
+   * the contents.
+   *
+   * @param $text
+   *   Plain text to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoUniqueText($text, $message = '', $group = 'Other') {
+    return $this->assertUniqueTextHelper($text, $message, $group, FALSE);
+  }
+
+  /**
+   * Helper for assertUniqueText and assertNoUniqueText.
+   *
+   * It is not recommended to call this function directly.
+   *
+   * @param $text
+   *   Plain text to look for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   * @param $be_unique
+   *   TRUE if this text should be found only once, FALSE if it should be found
+   *   more than once.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertUniqueTextHelper($text, $message = '', $group, $be_unique) {
+    if ($this->plainTextContent === FALSE) {
+      $this->plainTextContent = filter_xss($this->drupalGetContent(), array());
+    }
+    if (!$message) {
+      $message = '"' . $text . '"' . ($be_unique ? ' found only once' : ' found more than once');
+    }
+    $first_occurance = strpos($this->plainTextContent, $text);
+    if ($first_occurance === FALSE) {
+      return $this->assert(FALSE, $message, $group);
+    }
+    $offset = $first_occurance + strlen($text);
+    $second_occurance = strpos($this->plainTextContent, $text, $offset);
+    return $this->assert($be_unique == ($second_occurance === FALSE), $message, $group);
+  }
+
+  /**
+   * Triggers a pass if the Perl regex pattern is found in the raw content.
+   *
+   * @param $pattern
+   *   Perl regex to look for including the regex delimiters.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertPattern($pattern, $message = '', $group = 'Other') {
+    if (!$message) {
+      $message = t('Pattern "@pattern" found', array('@pattern' => $pattern));
+    }
+    return $this->assert((bool) preg_match($pattern, $this->drupalGetContent()), $message, $group);
+  }
+
+  /**
+   * Triggers a pass if the perl regex pattern is not found in raw content.
+   *
+   * @param $pattern
+   *   Perl regex to look for including the regex delimiters.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoPattern($pattern, $message = '', $group = 'Other') {
+    if (!$message) {
+      $message = t('Pattern "@pattern" not found', array('@pattern' => $pattern));
+    }
+    return $this->assert(!preg_match($pattern, $this->drupalGetContent()), $message, $group);
+  }
+
+  /**
+   * Pass if the page title is the given string.
+   *
+   * @param $title
+   *   The string the title should be.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertTitle($title, $message = '', $group = 'Other') {
+    $actual = (string) current($this->xpath('//title'));
+    if (!$message) {
+      $message = t('Page title @actual is equal to @expected.', array(
+        '@actual' => var_export($actual, TRUE),
+        '@expected' => var_export($title, TRUE),
+      ));
+    }
+    return $this->assertEqual($actual, $title, $message, $group);
+  }
+
+  /**
+   * Pass if the page title is not the given string.
+   *
+   * @param $title
+   *   The string the title should not be.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoTitle($title, $message = '', $group = 'Other') {
+    $actual = (string) current($this->xpath('//title'));
+    if (!$message) {
+      $message = t('Page title @actual is not equal to @unexpected.', array(
+        '@actual' => var_export($actual, TRUE),
+        '@unexpected' => var_export($title, TRUE),
+      ));
+    }
+    return $this->assertNotEqual($actual, $title, $message, $group);
+  }
+
+  /**
+   * Asserts themed output.
+   *
+   * @param $callback
+   *   The name of the theme function to invoke; e.g. 'links' for theme_links().
+   * @param $variables
+   *   An array of variables to pass to the theme function.
+   * @param $expected
+   *   The expected themed output string.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertThemeOutput($callback, array $variables = array(), $expected, $message = '', $group = 'Other') {
+    $output = theme($callback, $variables);
+    $this->verbose('Variables:' . '<pre>' .  check_plain(var_export($variables, TRUE)) . '</pre>'
+      . '<hr />' . 'Result:' . '<pre>' .  check_plain(var_export($output, TRUE)) . '</pre>'
+      . '<hr />' . 'Expected:' . '<pre>' .  check_plain(var_export($expected, TRUE)) . '</pre>'
+      . '<hr />' . $output
+    );
+    if (!$message) {
+      $message = '%callback rendered correctly.';
+    }
+    $message = format_string($message, array('%callback' => 'theme_' . $callback . '()'));
+    return $this->assertIdentical($output, $expected, $message, $group);
+  }
+
+  /**
+   * Asserts that a field exists in the current page by the given XPath.
+   *
+   * @param $xpath
+   *   XPath used to find the field.
+   * @param $value
+   *   (optional) Value of the field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertFieldByXPath($xpath, $value = NULL, $message = '', $group = 'Other') {
+    $fields = $this->xpath($xpath);
+
+    // If value specified then check array for match.
+    $found = TRUE;
+    if (isset($value)) {
+      $found = FALSE;
+      if ($fields) {
+        foreach ($fields as $field) {
+          if (isset($field['value']) && $field['value'] == $value) {
+            // Input element with correct value.
+            $found = TRUE;
+          }
+          elseif (isset($field->option)) {
+            // Select element found.
+            if ($this->getSelectedItem($field) == $value) {
+              $found = TRUE;
+            }
+            else {
+              // No item selected so use first item.
+              $items = $this->getAllOptions($field);
+              if (!empty($items) && $items[0]['value'] == $value) {
+                $found = TRUE;
+              }
+            }
+          }
+          elseif ((string) $field == $value) {
+            // Text area with correct text.
+            $found = TRUE;
+          }
+        }
+      }
+    }
+    return $this->assertTrue($fields && $found, $message, $group);
+  }
+
+  /**
+   * Get the selected value from a select field.
+   *
+   * @param $element
+   *   SimpleXMLElement select element.
+   *
+   * @return
+   *   The selected value or FALSE.
+   */
+  protected function getSelectedItem(\SimpleXMLElement $element) {
+    foreach ($element->children() as $item) {
+      if (isset($item['selected'])) {
+        return $item['value'];
+      }
+      elseif ($item->getName() == 'optgroup') {
+        if ($value = $this->getSelectedItem($item)) {
+          return $value;
+        }
+      }
+    }
+    return FALSE;
+  }
+
+  /**
+   * Asserts that a field does not exist in the current page by the given XPath.
+   *
+   * @param $xpath
+   *   XPath used to find the field.
+   * @param $value
+   *   (optional) Value of the field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoFieldByXPath($xpath, $value = NULL, $message = '', $group = 'Other') {
+    $fields = $this->xpath($xpath);
+
+    // If value specified then check array for match.
+    $found = TRUE;
+    if (isset($value)) {
+      $found = FALSE;
+      if ($fields) {
+        foreach ($fields as $field) {
+          if ($field['value'] == $value) {
+            $found = TRUE;
+          }
+        }
+      }
+    }
+    return $this->assertFalse($fields && $found, $message, $group);
+  }
+
+  /**
+   * Asserts that a field exists with the given name and value.
+   *
+   * @param $name
+   *   Name of field to assert.
+   * @param $value
+   *   Value of the field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertFieldByName($name, $value = NULL, $message = NULL, $group = 'Browser') {
+    if (!isset($message)) {
+      if (!isset($value)) {
+        $message = t('Found field with name @name', array(
+          '@name' => var_export($name, TRUE),
+        ));
+      }
+      else {
+        $message = t('Found field with name @name and value @value', array(
+          '@name' => var_export($name, TRUE),
+          '@value' => var_export($value, TRUE),
+        ));
+      }
+    }
+    return $this->assertFieldByXPath($this->constructFieldXpath('name', $name), $value, $message, $group);
+  }
+
+  /**
+   * Asserts that a field does not exist with the given name and value.
+   *
+   * @param $name
+   *   Name of field to assert.
+   * @param $value
+   *   Value of the field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoFieldByName($name, $value = '', $message = '', $group = 'Browser') {
+    return $this->assertNoFieldByXPath($this->constructFieldXpath('name', $name), $value, $message ? $message : t('Did not find field by name @name', array('@name' => $name)), $group);
+  }
+
+  /**
+   * Asserts that a field exists with the given id and value.
+   *
+   * @param $id
+   *   Id of field to assert.
+   * @param $value
+   *   Value of the field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertFieldById($id, $value = '', $message = '', $group = 'Browser') {
+    return $this->assertFieldByXPath($this->constructFieldXpath('id', $id), $value, $message ? $message : t('Found field by id @id', array('@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a field does not exist with the given id and value.
+   *
+   * @param $id
+   *   Id of field to assert.
+   * @param $value
+   *   Value of the field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoFieldById($id, $value = '', $message = '', $group = 'Browser') {
+    return $this->assertNoFieldByXPath($this->constructFieldXpath('id', $id), $value, $message ? $message : t('Did not find field by id @id', array('@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a checkbox field in the current page is checked.
+   *
+   * @param $id
+   *   Id of field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertFieldChecked($id, $message = '', $group = 'Browser') {
+    $elements = $this->xpath('//input[@id=:id]', array(':id' => $id));
+    return $this->assertTrue(isset($elements[0]) && !empty($elements[0]['checked']), $message ? $message : t('Checkbox field @id is checked.', array('@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a checkbox field in the current page is not checked.
+   *
+   * @param $id
+   *   Id of field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoFieldChecked($id, $message = '', $group = 'Browser') {
+    $elements = $this->xpath('//input[@id=:id]', array(':id' => $id));
+    return $this->assertTrue(isset($elements[0]) && empty($elements[0]['checked']), $message ? $message : t('Checkbox field @id is not checked.', array('@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a select option in the current page exists.
+   *
+   * @param $id
+   *   Id of select field to assert.
+   * @param $option
+   *   Option to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertOption($id, $option, $message = '', $group = 'Browser') {
+    $options = $this->xpath('//select[@id=:id]/option[@value=:option]', array(':id' => $id, ':option' => $option));
+    return $this->assertTrue(isset($options[0]), $message ? $message : t('Option @option for field @id exists.', array('@option' => $option, '@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a select option in the current page does not exist.
+   *
+   * @param $id
+   *   Id of select field to assert.
+   * @param $option
+   *   Option to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoOption($id, $option, $message = '', $group = 'Browser') {
+    $selects = $this->xpath('//select[@id=:id]', array(':id' => $id));
+    $options = $this->xpath('//select[@id=:id]/option[@value=:option]', array(':id' => $id, ':option' => $option));
+    return $this->assertTrue(isset($selects[0]) && !isset($options[0]), $message ? $message : t('Option @option for field @id does not exist.', array('@option' => $option, '@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a select option in the current page is checked.
+   *
+   * @param $id
+   *   Id of select field to assert.
+   * @param $option
+   *   Option to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   *
+   * @todo $id is unusable. Replace with $name.
+   */
+  protected function assertOptionSelected($id, $option, $message = '', $group = 'Browser') {
+    $elements = $this->xpath('//select[@id=:id]//option[@value=:option]', array(':id' => $id, ':option' => $option));
+    return $this->assertTrue(isset($elements[0]) && !empty($elements[0]['selected']), $message ? $message : t('Option @option for field @id is selected.', array('@option' => $option, '@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a select option in the current page is not checked.
+   *
+   * @param $id
+   *   Id of select field to assert.
+   * @param $option
+   *   Option to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoOptionSelected($id, $option, $message = '', $group = 'Browser') {
+    $elements = $this->xpath('//select[@id=:id]//option[@value=:option]', array(':id' => $id, ':option' => $option));
+    return $this->assertTrue(isset($elements[0]) && empty($elements[0]['selected']), $message ? $message : t('Option @option for field @id is not selected.', array('@option' => $option, '@id' => $id)), $group);
+  }
+
+  /**
+   * Asserts that a field exists with the given name or id.
+   *
+   * @param $field
+   *   Name or id of field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertField($field, $message = '', $group = 'Other') {
+    return $this->assertFieldByXPath($this->constructFieldXpath('name', $field) . '|' . $this->constructFieldXpath('id', $field), NULL, $message, $group);
+  }
+
+  /**
+   * Asserts that a field does not exist with the given name or id.
+   *
+   * @param $field
+   *   Name or id of field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoField($field, $message = '', $group = 'Other') {
+    return $this->assertNoFieldByXPath($this->constructFieldXpath('name', $field) . '|' . $this->constructFieldXpath('id', $field), NULL, $message, $group);
+  }
+
+  /**
+   * Asserts that each HTML ID is used for just a single element.
+   *
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   * @param $ids_to_skip
+   *   An optional array of ids to skip when checking for duplicates. It is
+   *   always a bug to have duplicate HTML IDs, so this parameter is to enable
+   *   incremental fixing of core code. Whenever a test passes this parameter,
+   *   it should add a "todo" comment above the call to this function explaining
+   *   the legacy bug that the test wishes to ignore and including a link to an
+   *   issue that is working to fix that legacy bug.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertNoDuplicateIds($message = '', $group = 'Other', $ids_to_skip = array()) {
+    $status = TRUE;
+    foreach ($this->xpath('//*[@id]') as $element) {
+      $id = (string) $element['id'];
+      if (isset($seen_ids[$id]) && !in_array($id, $ids_to_skip)) {
+        $this->fail(t('The HTML ID %id is unique.', array('%id' => $id)), $group);
+        $status = FALSE;
+      }
+      $seen_ids[$id] = TRUE;
+    }
+    return $this->assert($status, $message, $group);
+  }
+
+  /**
+   * Helper: Constructs an XPath for the given set of attributes and value.
+   *
+   * @param $attribute
+   *   Field attributes.
+   * @param $value
+   *   Value of field.
+   *
+   * @return
+   *   XPath for specified values.
+   */
+  protected function constructFieldXpath($attribute, $value) {
+    $xpath = '//textarea[@' . $attribute . '=:value]|//input[@' . $attribute . '=:value]|//select[@' . $attribute . '=:value]';
+    return $this->buildXPathQuery($xpath, array(':value' => $value));
+  }
+
+  /**
+   * Asserts the page responds with the specified response code.
+   *
+   * @param $code
+   *   Response code. For example 200 is a successful page request. For a list
+   *   of all codes see http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   Assertion result.
+   */
+  protected function assertResponse($code, $message = '', $group = 'Browser') {
+    $curl_code = curl_getinfo($this->curlHandle, CURLINFO_HTTP_CODE);
+    $match = is_array($code) ? in_array($curl_code, $code) : $curl_code == $code;
+    return $this->assertTrue($match, $message ? $message : t('HTTP response expected !code, actual !curl_code', array('!code' => $code, '!curl_code' => $curl_code)), $group);
+  }
+
+  /**
+   * Asserts the page did not return the specified response code.
+   *
+   * @param $code
+   *   Response code. For example 200 is a successful page request. For a list
+   *   of all codes see http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Browser'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   Assertion result.
+   */
+  protected function assertNoResponse($code, $message = '', $group = 'Browser') {
+    $curl_code = curl_getinfo($this->curlHandle, CURLINFO_HTTP_CODE);
+    $match = is_array($code) ? in_array($curl_code, $code) : $curl_code == $code;
+    return $this->assertFalse($match, $message ? $message : t('HTTP response not expected !code, actual !curl_code', array('!code' => $code, '!curl_code' => $curl_code)), $group);
+  }
+
+  /**
+   * Asserts that the most recently sent e-mail message has the given value.
+   *
+   * The field in $name must have the content described in $value.
+   *
+   * @param $name
+   *   Name of field or message property to assert. Examples: subject, body,
+   *   id, ...
+   * @param $value
+   *   Value of the field to assert.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'E-mail'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertMail($name, $value = '', $message = '', $group = 'E-mail') {
+    $captured_emails = \Drupal::state()->get('system.test_email_collector') ?: array();
+    $email = end($captured_emails);
+    return $this->assertTrue($email && isset($email[$name]) && $email[$name] == $value, $message, $group);
+  }
+
+  /**
+   * Asserts that the most recently sent e-mail message has the string in it.
+   *
+   * @param $field_name
+   *   Name of field or message property to assert: subject, body, id, ...
+   * @param $string
+   *   String to search for.
+   * @param $email_depth
+   *   Number of emails to search for string, starting with most recent.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertMailString($field_name, $string, $email_depth, $message = '', $group = 'Other') {
+    $mails = $this->drupalGetMails();
+    $string_found = FALSE;
+    for ($i = count($mails) -1; $i >= count($mails) - $email_depth && $i >= 0; $i--) {
+      $mail = $mails[$i];
+      // Normalize whitespace, as we don't know what the mail system might have
+      // done. Any run of whitespace becomes a single space.
+      $normalized_mail = preg_replace('/\s+/', ' ', $mail[$field_name]);
+      $normalized_string = preg_replace('/\s+/', ' ', $string);
+      $string_found = (FALSE !== strpos($normalized_mail, $normalized_string));
+      if ($string_found) {
+        break;
+      }
+    }
+    if (!$message) {
+      $message = format_string('Expected text found in @field of email message: "@expected".', array('@field' => $field_name, '@expected' => $string));
+    }
+    return $this->assertTrue($string_found, $message, $group);
+  }
+
+  /**
+   * Asserts that the most recently sent e-mail message has the pattern in it.
+   *
+   * @param $field_name
+   *   Name of field or message property to assert: subject, body, id, ...
+   * @param $regex
+   *   Pattern to search for.
+   * @param $message
+   *   (optional) A message to display with the assertion. Do not translate
+   *   messages: use format_string() to embed variables in the message text, not
+   *   t(). If left blank, a default message will be displayed.
+   * @param $group
+   *   (optional) The group this message is in, which is displayed in a column
+   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
+   *   translate this string. Defaults to 'Other'; most tests do not override
+   *   this default.
+   *
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function assertMailPattern($field_name, $regex, $message = '', $group = 'Other') {
+    $mails = $this->drupalGetMails();
+    $mail = end($mails);
+    $regex_found = preg_match("/$regex/", $mail[$field_name]);
+    if (!$message) {
+      $message = format_string('Expected text found in @field of email message: "@expected".', array('@field' => $field_name, '@expected' => $regex));
+    }
+    return $this->assertTrue($regex_found, $message, $group);
+  }
+
+  /**
+   * Outputs to verbose the most recent $count emails sent.
+   *
+   * @param $count
+   *   Optional number of emails to output.
+   */
+  protected function verboseEmail($count = 1) {
+    $mails = $this->drupalGetMails();
+    for ($i = count($mails) -1; $i >= count($mails) - $count && $i >= 0; $i--) {
+      $mail = $mails[$i];
+      $this->verbose(t('Email:') . '<pre>' . print_r($mail, TRUE) . '</pre>');
+    }
+  }
+
+  /**
+   * Creates a mock request and sets it on the generator.
+   *
+   * This is used to manipulate how the generator generates paths during tests.
+   * It also ensures that calls to $this->drupalGet() will work when running
+   * from run-tests.sh because the url generator no longer looks at the global
+   * variables that are set there but relies on getting this information from a
+   * request object.
+   *
+   * @param bool $clean_urls
+   *   Whether to mock the request using clean urls.
+   * @param $override_server_vars
+   *   An array of server variables to override.
+   *
+   * @return $request
+   *   The mocked request object.
+   */
+  protected function prepareRequestForGenerator($clean_urls = TRUE, $override_server_vars = array()) {
+    $generator = $this->container->get('url_generator');
+    $request = Request::createFromGlobals();
+    $server = $request->server->all();
+    if (basename($server['SCRIPT_FILENAME']) != basename($server['SCRIPT_NAME'])) {
+      // We need this for when the test is executed by run-tests.sh.
+      // @todo Remove this once run-tests.sh has been converted to use a Request
+      //   object.
+      $cwd = getcwd();
+      $server['SCRIPT_FILENAME'] = $cwd . '/' . basename($server['SCRIPT_NAME']);
+      $base_path = rtrim($server['REQUEST_URI'], '/');
+    }
+    else {
+      $base_path = $request->getBasePath();
+    }
+    if ($clean_urls) {
+      $request_path = $base_path ? $base_path . '/user' : 'user';
+    }
+    else {
+      $request_path = $base_path ? $base_path . '/index.php/user' : '/index.php/user';
+    }
+    $server = array_merge($server, $override_server_vars);
+
+    $request = Request::create($request_path, 'GET', array(), array(), array(), $server);
+    $generator->setRequest($request);
+    return $request;
+  }
+}