diff --git a/core/modules/field/lib/Drupal/field/Tests/DisplayApiTest.php b/core/modules/field/lib/Drupal/field/Tests/DisplayApiTest.php
index 88001f0..b2eaace 100644
--- a/core/modules/field/lib/Drupal/field/Tests/DisplayApiTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/DisplayApiTest.php
@@ -124,7 +124,7 @@ function testFieldItemListView() {
 
     // No display settings: check that default display settings are used.
     $output = $items->view();
-    $this->content = drupal_render($output);
+    $this->render($output);
     $settings = \Drupal::service('plugin.manager.field.formatter')->getDefaultSettings('field_test_default');
     $setting = $settings['test_formatter_setting'];
     $this->assertText($this->label, 'Label was displayed.');
@@ -142,7 +142,7 @@ function testFieldItemListView() {
       ),
     );
     $output = $items->view($display);
-    $this->content = drupal_render($output);
+    $this->render($output);
     $setting = $display['settings']['test_formatter_setting_multiple'];
     $this->assertNoText($this->label, 'Label was not displayed.');
     $this->assertText('field_test_entity_display_build_alter', 'Alter fired, display passed.');
@@ -162,8 +162,7 @@ function testFieldItemListView() {
       ),
     );
     $output = $items->view($display);
-    $view = drupal_render($output);
-    $this->content = $view;
+    $view = $this->render($output);
     $setting = $display['settings']['test_formatter_setting_additional'];
     $this->assertNoText($this->label, 'Label was not displayed.');
     $this->assertNoText('field_test_entity_display_build_alter', 'Alter not fired.');
@@ -174,7 +173,7 @@ function testFieldItemListView() {
     // View mode: check that display settings specified in the display object
     // are used.
     $output = $items->view('teaser');
-    $this->content = drupal_render($output);
+    $this->render($output);
     $setting = $this->display_options['teaser']['settings']['test_formatter_setting'];
     $this->assertText($this->label, 'Label was displayed.');
     foreach ($this->values as $delta => $value) {
@@ -184,7 +183,7 @@ function testFieldItemListView() {
     // Unknown view mode: check that display settings for 'default' view mode
     // are used.
     $output = $items->view('unknown_view_mode');
-    $this->content = drupal_render($output);
+    $this->render($output);
     $setting = $this->display_options['default']['settings']['test_formatter_setting'];
     $this->assertText($this->label, 'Label was displayed.');
     foreach ($this->values as $delta => $value) {
@@ -202,7 +201,7 @@ function testFieldItemView() {
     foreach ($this->values as $delta => $value) {
       $item = $this->entity->{$this->field_name}[$delta];
       $output = $item->view();
-      $this->content = drupal_render($output);
+      $this->render($output);
       $this->assertText($setting . '|' . $value['value'], format_string('Value @delta was displayed with expected setting.', array('@delta' => $delta)));
     }
 
@@ -217,7 +216,7 @@ function testFieldItemView() {
     foreach ($this->values as $delta => $value) {
       $item = $this->entity->{$this->field_name}[$delta];
       $output = $item->view($display);
-      $this->content = drupal_render($output);
+      $this->render($output);
       $this->assertText($setting . '|0:' . $value['value'], format_string('Value @delta was displayed with expected setting.', array('@delta' => $delta)));
     }
 
@@ -232,7 +231,7 @@ function testFieldItemView() {
     foreach ($this->values as $delta => $value) {
       $item = $this->entity->{$this->field_name}[$delta];
       $output = $item->view($display);
-      $this->content = drupal_render($output);
+      $this->render($output);
       $this->assertText($setting . '|' . $value['value'] . '|' . ($value['value'] + 1), format_string('Value @delta was displayed with expected setting.', array('@delta' => $delta)));
     }
 
@@ -242,7 +241,7 @@ function testFieldItemView() {
     foreach ($this->values as $delta => $value) {
       $item = $this->entity->{$this->field_name}[$delta];
       $output = $item->view('teaser');
-      $this->content = drupal_render($output);
+      $this->render($output);
       $this->assertText($setting . '|' . $value['value'], format_string('Value @delta was displayed with expected setting.', array('@delta' => $delta)));
     }
 
@@ -252,7 +251,7 @@ function testFieldItemView() {
     foreach ($this->values as $delta => $value) {
       $item = $this->entity->{$this->field_name}[$delta];
       $output = $item->view('unknown_view_mode');
-      $this->content = drupal_render($output);
+      $this->render($output);
       $this->assertText($setting . '|' . $value['value'], format_string('Value @delta was displayed with expected setting.', array('@delta' => $delta)));
     }
   }
@@ -272,8 +271,7 @@ function testFieldEmpty() {
     // $this->entity is set by the setUp() method and by default contains 4
     // numeric values.  We only want to test the display of this one field.
     $output = $this->entity->get($this->field_name)->view($display);
-    $view = drupal_render($output);
-    $this->content = $view;
+    $view = $this->render($output);
     // The test field by default contains values, so should not display the
     // default "empty" text.
     $this->assertNoText($display['settings']['test_empty_string']);
@@ -282,8 +280,7 @@ function testFieldEmpty() {
     $this->entity->{$this->field_name} = array();
     $this->entity->save();
     $output = $this->entity->get($this->field_name)->view($display);
-    $view = drupal_render($output);
-    $this->content = $view;
+    $view = $this->render($output);
     // This time, as the field values have been removed, we *should* show the
     // default "empty" text.
     $this->assertText($display['settings']['test_empty_string']);
diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldAttachOtherTest.php b/core/modules/field/lib/Drupal/field/Tests/FieldAttachOtherTest.php
index 39f6e28..c37e09d 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldAttachOtherTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldAttachOtherTest.php
@@ -83,7 +83,7 @@ function testEntityDisplayBuild() {
 
     // View all fields.
     $content = $display->build($entity);
-    $this->content = drupal_render($content);
+    $this->render($content);
     $this->assertRaw($this->instance->getLabel(), "First field's label is displayed.");
     foreach ($values as $delta => $value) {
       $this->assertRaw("$formatter_setting|{$value['value']}", "Value $delta is displayed, formatter settings are applied.");
@@ -98,14 +98,14 @@ function testEntityDisplayBuild() {
     $display_options['label'] = 'hidden';
     $display->setComponent($this->field->getName(), $display_options);
     $content = $display->build($entity);
-    $this->content = drupal_render($content);
+    $this->render($content);
     $this->assertNoRaw($this->instance->getLabel(), "Hidden label: label is not displayed.");
 
     // Field hidden.
     $entity = clone($entity_init);
     $display->removeComponent($this->field->getName());
     $content = $display->build($entity);
-    $this->content = drupal_render($content);
+    $this->render($content);
     $this->assertNoRaw($this->instance->getLabel(), "Hidden field: label is not displayed.");
     foreach ($values as $delta => $value) {
       $this->assertNoRaw("$formatter_setting|{$value['value']}", "Hidden field: value $delta is not displayed.");
@@ -122,7 +122,7 @@ function testEntityDisplayBuild() {
       ),
     ));
     $content = $display->build($entity);
-    $this->content = drupal_render($content);
+    $this->render($content);
     $expected_output = $formatter_setting;
     foreach ($values as $delta => $value) {
       $expected_output .= "|$delta:{$value['value']}";
@@ -140,7 +140,7 @@ function testEntityDisplayBuild() {
       ),
     ));
     $content = $display->build($entity);
-    $this->content = drupal_render($content);
+    $this->render($content);
     foreach ($values as $delta => $value) {
       $expected = $formatter_setting . '|' . $value['value'] . '|' . ($value['value'] + 1);
       $this->assertRaw($expected, "Value $delta is displayed, formatter settings are applied.");
diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldUnitTestBase.php b/core/modules/field/lib/Drupal/field/Tests/FieldUnitTestBase.php
index 5f77d92..c249bd2 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldUnitTestBase.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldUnitTestBase.php
@@ -25,13 +25,6 @@
   public static $modules = array('user', 'entity', 'system', 'field', 'text', 'entity_test', 'field_test');
 
   /**
-   * A string for assert raw and text helper methods.
-   *
-   * @var string
-   */
-  protected $content;
-
-  /**
    * Set the default field storage backend for fields created during tests.
    */
   function setUp() {
@@ -163,104 +156,4 @@ function assertFieldValues(EntityInterface $entity, $field_name, $expected_value
     }
   }
 
-  /**
-   * Pass if the raw text IS found in set string.
-   *
-   * @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->content, $raw) !== FALSE, $message, $group);
-  }
-
-
-  /**
-   * Pass if the raw text IS NOT found in set string.
-   *
-   * @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" found', array('@raw' => $raw));
-    }
-    return $this->assert(strpos($this->content, $raw) === FALSE, $message, $group);
-  }
-
-  /**
-   * Pass if the text IS found in set string.
-   *
-   * @param $text
-   *   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 = '', $group = 'Other') {
-    if (!$message) {
-      $message = t('Raw "@raw" found', array('@raw' => $text));
-    }
-    return $this->assert(strpos(Xss::filter($this->content, array()), $text) !== FALSE, $message, $group);
-  }
-
-  /**
-   * Pass if the text IS NOT found in set string.
-   *
-   * @param $text
-   *   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 = '', $group = 'Other') {
-    if (!$message) {
-      $message = t('Raw "@raw" not found', array('@raw' => $text));
-    }
-    return $this->assert(strpos(Xss::filter($this->content, array()), $text) === FALSE, $message, $group);
-  }
 }
diff --git a/core/modules/field/lib/Drupal/field/Tests/FormTest.php b/core/modules/field/lib/Drupal/field/Tests/FormTest.php
index bbfccb7..a82a490 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FormTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FormTest.php
@@ -427,7 +427,7 @@ function testFieldFormJSAddMore() {
     // Press 'add more' button through Ajax, and place the expected HTML result
     // as the tested content.
     $commands = $this->drupalPostAjaxForm(NULL, $edit, $field_name . '_add_more');
-    $this->content = $commands[1]['data'];
+    $this->setRawContent($commands[1]['data']);
 
     for ($delta = 0; $delta <= $delta_range; $delta++) {
       $this->assertFieldByName("{$field_name}[$delta][value]", $values[$delta], "Widget $delta is displayed and has the right value");
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/AssertContentTrait.php b/core/modules/simpletest/lib/Drupal/simpletest/AssertContentTrait.php
new file mode 100644
index 0000000..47b3f95
--- /dev/null
+++ b/core/modules/simpletest/lib/Drupal/simpletest/AssertContentTrait.php
@@ -0,0 +1,1174 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\simpletest\AssertContentTrait.
+ */
+
+namespace Drupal\simpletest;
+
+use Drupal\Component\Serialization\Json;
+use Drupal\Component\Utility\String;
+use Drupal\Component\Utility\Xss;
+
+/**
+ * Provides test methods to assert content.
+ */
+trait AssertContentTrait {
+
+  /**
+   * The current raw content.
+   *
+   * @var string
+   */
+  protected $content;
+
+  /**
+   * The plain-text content of raw $content (text nodes).
+   *
+   * @var string
+   */
+  protected $plainTextContent;
+
+  /**
+   * The drupalSettings value from the current raw $content.
+   *
+   * drupalSettings refers to the drupalSettings JavaScript variable.
+   *
+   * @var array
+   */
+  protected $drupalSettings;
+
+  /**
+   * The XML structure parsed from the current raw $content.
+   *
+   * @var \SimpleXMLElement
+   */
+  protected $elements;
+
+  /**
+   * Gets the current raw content.
+   */
+  protected function getRawContent() {
+    return $this->content;
+  }
+
+  /**
+   * Sets the raw content (e.g. HTML).
+   *
+   * @param string $content
+   *   The raw content to set.
+   */
+  protected function setRawContent($content) {
+    $this->content = $content;
+    $this->plainTextContent = NULL;
+    $this->elements = NULL;
+    $this->drupalSettings = array();
+    if (preg_match('/var drupalSettings = (.*?);$/m', $content, $matches)) {
+      $this->drupalSettings = Json::decode($matches[1]);
+    }
+  }
+
+  /**
+   * Retrieves the plain-text content from the current raw content.
+   */
+  protected function getTextContent() {
+    if (!isset($this->plainTextContent)) {
+      $this->plainTextContent = Xss::filter($this->getRawContent(), array());
+    }
+    return $this->plainTextContent;
+  }
+
+  /**
+   * Gets the value of drupalSettings for the currently-loaded page.
+   *
+   * drupalSettings refers to the drupalSettings JavaScript variable.
+   */
+  protected function getDrupalSettings() {
+    return $this->drupalSettings;
+  }
+
+  /**
+   * Sets the value of drupalSettings for the currently-loaded page.
+   *
+   * drupalSettings refers to the drupalSettings JavaScript variable.
+   */
+  protected function setDrupalSettings($settings) {
+    $this->drupalSettings = $settings;
+  }
+
+  /**
+   * Parse content returned from curlExec using DOM and SimpleXML.
+   *
+   * @return
+   *   A SimpleXMLElement or FALSE on failure.
+   */
+  protected function parse() {
+    if (!isset($this->elements)) {
+      // DOM can load HTML soup. But, HTML soup can throw warnings, suppress
+      // them.
+      $htmlDom = new \DOMDocument();
+      @$htmlDom->loadHTML('<?xml encoding="UTF-8">' . $this->getRawContent());
+      if ($htmlDom) {
+        $this->pass(String::format('Valid HTML found on "@path"', array('@path' => $this->getUrl())), '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 === FALSE) {
+      $this->fail('Parsed page successfully.', 'Browser');
+    }
+
+    return $this->elements;
+  }
+
+  /**
+   * 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 string $xpath
+   *   An XPath query, possibly with placeholders in the form ':name'.
+   * @param array $args
+   *   An array of arguments with keys in the form ':name' matching the
+   *   placeholders in the query. The values may be either strings or numeric
+   *   values.
+   *
+   * @return string
+   *   An XPath query with arguments replaced.
+   */
+  protected function buildXPathQuery($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 string $xpath
+   *   The xpath string to use in the search.
+   * @param array $arguments
+   *   An array of arguments with keys in the form ':name' matching the
+   *   placeholders in the query. The values may be either strings or numeric
+   *   values.
+   *
+   * @return array
+   *   The return value of the xpath search. For details on the xpath string
+   *   format and return values see the SimpleXML documentation,
+   *   http://php.net/manual/function.simplexml-element-xpath.php.
+   */
+  protected function xpath($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 : String::format('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 : String::format('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 : String::format('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 : String::format('No link containing href %href found.', array('%href' => $href)));
+    return $this->assert(empty($links), $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 = String::format('Raw "@raw" found', array('@raw' => $raw));
+    }
+    return $this->assert(strpos($this->getRawContent(), $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 = String::format('Raw "@raw" not found', array('@raw' => $raw));
+    }
+    return $this->assert(strpos($this->getRawContent(), $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, $not_exists) {
+    if (!$message) {
+      $message = !$not_exists ? String::format('"@text" found', array('@text' => $text)) : String::format('"@text" not found', array('@text' => $text));
+    }
+    return $this->assert($not_exists == (strpos($this->getTextContent(), $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, $be_unique) {
+    if (!$message) {
+      $message = '"' . $text . '"' . ($be_unique ? ' found only once' : ' found more than once');
+    }
+    $first_occurance = strpos($this->getTextContent(), $text);
+    if ($first_occurance === FALSE) {
+      return $this->assert(FALSE, $message, $group);
+    }
+    $offset = $first_occurance + strlen($text);
+    $second_occurance = strpos($this->getTextContent(), $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 = String::format('Pattern "@pattern" found', array('@pattern' => $pattern));
+    }
+    return $this->assert((bool) preg_match($pattern, $this->getRawContent()), $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 = String::format('Pattern "@pattern" not found', array('@pattern' => $pattern));
+    }
+    return $this->assert(!preg_match($pattern, $this->getRawContent()), $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) {
+      $message = String::format('Page title @actual is equal to @expected.', array(
+        '@actual' => var_export($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) {
+      $message = String::format('Page title @actual is not equal to @unexpected.', array(
+        '@actual' => var_export($actual, TRUE),
+        '@unexpected' => var_export($title, TRUE),
+      ));
+    }
+    return $this->assertNotEqual($actual, $title, $message, $group);
+  }
+
+  /**
+   * Asserts themed output.
+   *
+   * @param $callback
+   *   The name of the theme hook to invoke; e.g. 'links' for links.html.twig.
+   * @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.
+            $selected = $this->getSelectedItem($field);
+            if ($selected === FALSE) {
+              // No item selected so use first item.
+              $items = $this->getAllOptions($field);
+              if (!empty($items) && $items[0]['value'] == $value) {
+                $found = TRUE;
+              }
+            }
+            elseif ($selected == $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)) {
+        $message = String::format('Found field with name @name', array(
+          '@name' => var_export($name, TRUE),
+        ));
+      }
+      else {
+        $message = String::format('Found field with name @name and value @value', array(
+          '@name' => var_export($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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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(String::format('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));
+  }
+
+}
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
index d6bd64f..93402f4 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\simpletest;
 
+use Drupal\Component\Utility\String;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\KeyValueStore\KeyValueMemoryFactory;
@@ -31,6 +32,8 @@
  */
 abstract class DrupalUnitTestBase extends UnitTestBase {
 
+  use AssertContentTrait;
+
   /**
    * Modules to enable.
    *
@@ -465,4 +468,20 @@ protected function unregisterStreamWrapper($scheme, $type) {
     }
   }
 
+  /**
+   * Renders a render array.
+   *
+   * @param array $elements
+   *   The elements to render.
+   *
+   * @return string
+   *   The rendered string output (typically HTML).
+   */
+  protected function render(array $elements) {
+    $content = drupal_render($elements);
+    $this->setRawContent($content);
+    $this->verbose('<pre style="white-space: pre-wrap">' . String::checkPlain($content));
+    return $content;
+  }
+
 }
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 7cfbc58..e6aa041 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -29,6 +29,8 @@
  */
 abstract class WebTestBase extends TestBase {
 
+  use AssertContentTrait;
+
   /**
    * The profile to install as a basis for testing.
    *
@@ -68,36 +70,6 @@
   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 $elements = NULL;
-
-  /**
    * The current user logged in using the internal browser.
    *
    * @var bool
@@ -1297,16 +1269,18 @@ protected function curlExec($curl_options, $redirect = FALSE) {
       }
     }
 
-    $this->drupalSetContent($content, isset($original_url) ? $original_url : curl_getinfo($this->curlHandle, CURLINFO_EFFECTIVE_URL));
+    $this->setRawContent($content);
+    $this->url = isset($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()))
+      '!length' => format_size(strlen($this->getRawContent()))
     );
     $message = String::format('!method @url returned @status (!length).', $message_vars);
-    $this->assertTrue($this->drupalGetContent() !== FALSE, $message, 'Browser');
-    return $this->drupalGetContent();
+    $this->assertTrue($this->getRawContent() !== FALSE, $message, 'Browser');
+    return $this->getRawContent();
   }
 
   /**
@@ -1386,32 +1360,6 @@ protected function isInChildSite() {
   }
 
   /**
-   * 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(String::format('Valid HTML found on "@path"', array('@path' => $this->getUrl())), '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('Parsed page successfully.', 'Browser');
-    }
-
-    return $this->elements;
-  }
-
-  /**
    * Retrieves a Drupal path or an absolute path.
    *
    * @param $path
@@ -1423,7 +1371,7 @@ protected function parse() {
    *   "name: value".
    *
    * @return
-   *   The retrieved HTML string, also available as $this->drupalGetContent()
+   *   The retrieved HTML string, also available as $this->getRawContent()
    */
   protected function drupalGet($path, array $options = array(), array $headers = array()) {
     $options['absolute'] = TRUE;
@@ -1884,8 +1832,8 @@ protected function drupalProcessAjaxResponse($content, array $ajax_response, arr
       }
     }
     $content = $dom->saveHTML();
-    $this->drupalSetContent($content);
-    $this->drupalSetSettings($drupal_settings);
+    $this->setRawContent($content);
+    $this->setDrupalSettings($drupal_settings);
   }
 
   /**
@@ -2005,7 +1953,7 @@ protected function cronRun() {
    *   Either the new page content or FALSE.
    */
   protected function checkForMetaRefresh() {
-    if (strpos($this->drupalGetContent(), '<meta ') && $this->parse()) {
+    if (strpos($this->getRawContent(), '<meta ') && $this->parse()) {
       $refresh = $this->xpath('//meta[@http-equiv="Refresh"]');
       if (!empty($refresh)) {
         // Parse the content attribute of the meta tag for the format:
@@ -2030,7 +1978,7 @@ protected function checkForMetaRefresh() {
    *   "name: value".
    *
    * @return
-   *   The retrieved headers, also available as $this->drupalGetContent()
+   *   The retrieved headers, also available as $this->getRawContent()
    */
   protected function drupalHead($path, array $options = array(), array $headers = array()) {
     $options['absolute'] = TRUE;
@@ -2210,215 +2158,6 @@ protected function handleForm(&$post, &$edit, &$upload, $submit, $form) {
   }
 
   /**
-   * 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 string $xpath
-   *   An XPath query, possibly with placeholders in the form ':name'.
-   * @param array $args
-   *   An array of arguments with keys in the form ':name' matching the
-   *   placeholders in the query. The values may be either strings or numeric
-   *   values.
-   *
-   * @return string
-   *   An XPath query with arguments replaced.
-   */
-  protected function buildXPathQuery($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 string $xpath
-   *   The xpath string to use in the search.
-   * @param array $arguments
-   *   An array of arguments with keys in the form ':name' matching the
-   *   placeholders in the query. The values may be either strings or numeric
-   *   values.
-   *
-   * @return array
-   *   The return value of the xpath search. For details on the xpath string
-   *   format and return values see the SimpleXML documentation,
-   *   http://php.net/manual/function.simplexml-element-xpath.php.
-   */
-  protected function xpath($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 : String::format('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 : String::format('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 : String::format('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 : String::format('No link containing href %href found.', array('%href' => $href)));
-    return $this->assert(empty($links), $message, $group);
-  }
-
-  /**
    * Follows a link by name.
    *
    * Will click the first link found with this link text by default, or a later
@@ -2582,18 +2321,22 @@ protected function drupalGetHeader($name, $all_requests = FALSE) {
 
   /**
    * Gets the current raw HTML of requested page.
+   *
+   * @deprecated 8.x
+   *   Use getRawContent().
    */
   protected function drupalGetContent() {
-    return $this->content;
+    return $this->getRawContent();
   }
 
   /**
    * Gets the value of drupalSettings for the currently-loaded page.
    *
-   * drupalSettings refers to the drupalSettings JavaScript variable.
+   * @deprecated 8.x
+   *   Use getDrupalSettings().
    */
   protected function drupalGetSettings() {
-    return $this->drupalSettings;
+    return $this->getDrupalSettings();
   }
 
   /**
@@ -2625,31 +2368,21 @@ protected function drupalGetMails($filter = array()) {
   /**
    * Sets the raw HTML content.
    *
-   * This can be useful when a page has been fetched outside of the internal
-   * browser and assertions need to be made on the returned page.
-   *
-   * A good example would be when testing HTTP request made by Drupal. After
-   * fetching the page the content can be set and page elements can be checked
-   * to ensure that the function worked properly.
+   * @deprecated 8.x
+   *   Use setRawContent().
    */
-  protected function drupalSetContent($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)) {
-      $this->drupalSettings = Json::decode($matches[1]);
-    }
+  protected function drupalSetContent($content) {
+    $this->setRawContent($content);
   }
 
   /**
    * Sets the value of drupalSettings for the currently-loaded page.
    *
-   * drupalSettings refers to the drupalSettings JavaScript variable.
+   * @deprecated 8.x
+   *   Use setDrupalSettings().
    */
   protected function drupalSetSettings($settings) {
-    $this->drupalSettings = $settings;
+    $this->setDrupalSettings($settings);
   }
 
   /**
@@ -2687,851 +2420,6 @@ protected function assertUrl($path, array $options = array(), $message = '', $gr
   }
 
   /**
-   * 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 = String::format('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 = String::format('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) {
-      $this->plainTextContent = Xss::filter($this->drupalGetContent(), array());
-    }
-    if (!$message) {
-      $message = !$not_exists ? String::format('"@text" found', array('@text' => $text)) : String::format('"@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) {
-      $this->plainTextContent = Xss::filter($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 = String::format('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 = String::format('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) {
-      $message = String::format('Page title @actual is equal to @expected.', array(
-        '@actual' => var_export($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) {
-      $message = String::format('Page title @actual is not equal to @unexpected.', array(
-        '@actual' => var_export($actual, TRUE),
-        '@unexpected' => var_export($title, TRUE),
-      ));
-    }
-    return $this->assertNotEqual($actual, $title, $message, $group);
-  }
-
-  /**
-   * Asserts themed output.
-   *
-   * @param $callback
-   *   The name of the theme hook to invoke; e.g. 'links' for links.html.twig.
-   * @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.
-            $selected = $this->getSelectedItem($field);
-            if ($selected === FALSE) {
-              // No item selected so use first item.
-              $items = $this->getAllOptions($field);
-              if (!empty($items) && $items[0]['value'] == $value) {
-                $found = TRUE;
-              }
-            }
-            elseif ($selected == $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)) {
-        $message = String::format('Found field with name @name', array(
-          '@name' => var_export($name, TRUE),
-        ));
-      }
-      else {
-        $message = String::format('Found field with name @name and value @value', array(
-          '@name' => var_export($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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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 : String::format('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(String::format('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 $code
diff --git a/core/modules/simpletest/tests/Drupal/simpletest/Tests/WebTestBaseTest.php b/core/modules/simpletest/tests/Drupal/simpletest/Tests/WebTestBaseTest.php
index bbfdadd..8617867 100644
--- a/core/modules/simpletest/tests/Drupal/simpletest/Tests/WebTestBaseTest.php
+++ b/core/modules/simpletest/tests/Drupal/simpletest/Tests/WebTestBaseTest.php
@@ -66,11 +66,11 @@ public function testAssertFieldByName($filename, $name, $value, $expected) {
 
     $web_test = $this->getMockBuilder('Drupal\simpletest\WebTestBase')
       ->disableOriginalConstructor()
-      ->setMethods(array('assertTrue', 'drupalGetContent', 'pass'))
+      ->setMethods(array('getRawContent', 'assertTrue', 'pass'))
       ->getMock();
 
     $web_test->expects($this->any())
-      ->method('drupalGetContent')
+      ->method('getRawContent')
       ->will($this->returnValue($content));
 
     $web_test->expects($this->once())
diff --git a/core/modules/system/lib/Drupal/system/Tests/Theme/TableTest.php b/core/modules/system/lib/Drupal/system/Tests/Theme/TableTest.php
index 26a0fd8..fa4b819 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Theme/TableTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/TableTest.php
@@ -41,7 +41,7 @@ function testThemeTableStickyHeaders() {
       '#rows' => $rows,
       '#sticky' => TRUE,
     );
-    $this->content = drupal_render($table);
+    $this->render($table);
     $js = _drupal_add_js();
     $this->assertTrue(isset($js['core/misc/tableheader.js']), 'tableheader.js was included when $sticky = TRUE.');
     $this->assertRaw('sticky-enabled',  'Table has a class of sticky-enabled when $sticky = TRUE.');
@@ -66,7 +66,7 @@ function testThemeTableNoStickyHeaders() {
       '#colgroups' => $colgroups,
       '#sticky' => FALSE,
     );
-    $this->content = drupal_render($table);
+    $this->render($table);
     $js = _drupal_add_js();
     $this->assertFalse(isset($js['core/misc/tableheader.js']), 'tableheader.js was not included because $sticky = FALSE.');
     $this->assertNoRaw('sticky-enabled',  'Table does not have a class of sticky-enabled because $sticky = FALSE.');
@@ -91,7 +91,7 @@ function testThemeTableWithEmptyMessage() {
       '#rows' => array(),
       '#empty' => t('No strings available.'),
     );
-    $this->content = drupal_render($table);
+    $this->render($table);
     $this->assertRaw('<tr class="odd"><td colspan="3" class="empty message">No strings available.</td>', 'Correct colspan was set on empty message.');
     $this->assertRaw('<thead><tr><th>Header 1</th>', 'Table header was printed.');
   }
@@ -110,7 +110,7 @@ function testThemeTableWithNoStriping() {
       '#type' => 'table',
       '#rows' => $rows,
     );
-    $this->content = drupal_render($table);
+    $this->render($table);
     $this->assertNoRaw('class="odd"', 'Odd/even classes were not added because $no_striping = TRUE.');
     $this->assertNoRaw('no_striping', 'No invalid no_striping HTML attribute was printed.');
   }
@@ -130,42 +130,8 @@ function testThemeTableHeaderCellOption() {
       '#type' => 'table',
       '#rows' => $rows,
     );
-    $this->content = drupal_render($table);
+    $this->render($table);
     $this->assertRaw('<th>1</th><td>1</td><td>1</td>', 'The th and td tags was printed correctly.');
   }
 
-  /**
-   * Asserts that a raw string appears in $this->content.
-   *
-   * @param string $value
-   *   The expected string.
-   * @param string $message
-   *   (optional) A custom assertion message.
-   */
-  protected function assertRaw($value, $message = NULL) {
-    if (!isset($message)) {
-      $message = String::format("Raw value @value found.", array(
-        '@value' => var_export($value, TRUE),
-      ));
-    }
-    $this->assert(strpos($this->content, $value) !== FALSE, $message);
-  }
-
-  /**
-   * Asserts that a raw string does not appear in $this->content.
-   *
-   * @param string $value
-   *   The not expected string.
-   * @param string $message
-   *   (optional) A custom assertion message.
-   */
-  protected function assertNoRaw($value, $message = NULL) {
-    if (!isset($message)) {
-      $message = String::format("Raw value @value not found.", array(
-        '@value' => var_export($value, TRUE),
-      ));
-    }
-    $this->assert(strpos($this->content, $value) === FALSE, $message);
-  }
-
 }
diff --git a/core/modules/text/lib/Drupal/text/Tests/Formatter/TextPlainUnitTest.php b/core/modules/text/lib/Drupal/text/Tests/Formatter/TextPlainUnitTest.php
index 8e37920..07c4fe3 100644
--- a/core/modules/text/lib/Drupal/text/Tests/Formatter/TextPlainUnitTest.php
+++ b/core/modules/text/lib/Drupal/text/Tests/Formatter/TextPlainUnitTest.php
@@ -28,13 +28,6 @@ class TextPlainUnitTest extends DrupalUnitTestBase {
    */
   public static $modules = array('entity', 'field', 'text', 'entity_test', 'system', 'filter', 'user');
 
-  /**
-   * Contains rendered content.
-   *
-   * @var string
-   */
-  protected $content;
-
   public static function getInfo() {
     return array(
       'name'  => 'Text field text_plain formatter',
@@ -123,8 +116,8 @@ protected function createEntity($values = array()) {
    */
   protected function renderEntityFields(ContentEntityInterface $entity, EntityViewDisplayInterface $display) {
     $content = $display->build($entity);
-    $this->content = drupal_render($content);
-    return $this->content;
+    $content = $this->render($content);
+    return $content;
   }
 
   /**
diff --git a/core/modules/views/lib/Drupal/views/Tests/Plugin/RowEntityTest.php b/core/modules/views/lib/Drupal/views/Tests/Plugin/RowEntityTest.php
index 0b406f5..aed7874 100644
--- a/core/modules/views/lib/Drupal/views/Tests/Plugin/RowEntityTest.php
+++ b/core/modules/views/lib/Drupal/views/Tests/Plugin/RowEntityTest.php
@@ -32,13 +32,6 @@ class RowEntityTest extends ViewUnitTestBase {
    */
   public static $testViews = array('test_entity_row');
 
-  /**
-   * A string for assert raw and text helper methods.
-   *
-   * @var string
-   */
-  protected $content;
-
   public static function getInfo() {
     return array(
       'name' => 'Row: Entity',
@@ -68,8 +61,7 @@ public function testEntityRow() {
     $term->save();
 
     $view = Views::getView('test_entity_row');
-    $this->content = $view->preview();
-    $this->content = drupal_render($this->content);
+    $this->render($view->preview());
 
     $this->assertText($term->getName(), 'The rendered entity appears as row in the view.');
 
@@ -82,28 +74,4 @@ public function testEntityRow() {
     $this->assertTrue(isset($form['view_mode']['#options']['default']), 'Ensure that the default view mode is available');
   }
 
-  /**
-   * Pass if the text is found in set string.
-   *
-   * @param string $text
-   *   Text to look for.
-   * @param string $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 string $group
-   *   (optional) The group this message is in, which is displayed in a column
-   *   in test output. Use 'Debug' to indicate this is debugging output. Do not
-   *   translate this string. Defaults to 'Other'; most tests do not override
-   *   this default.
-   *
-   * @return bool TRUE on pass, FALSE on fail.
-   */
-  protected function assertText($text, $message = '', $group = 'Other') {
-    if (!$message) {
-      $message = t('Raw "@raw" found', array('@raw' => $text));
-    }
-    return $this->assert(strpos(Xss::filter($this->content, array()), $text) !== FALSE, $message, $group);
-  }
-
 }
diff --git a/core/modules/views/lib/Drupal/views/Tests/Plugin/StyleGridTest.php b/core/modules/views/lib/Drupal/views/Tests/Plugin/StyleGridTest.php
index e9132b1..dfa4e30 100644
--- a/core/modules/views/lib/Drupal/views/Tests/Plugin/StyleGridTest.php
+++ b/core/modules/views/lib/Drupal/views/Tests/Plugin/StyleGridTest.php
@@ -83,7 +83,7 @@ protected function assertGrid(ViewExecutable $view, $alignment, $columns) {
     $this->executeView($view);
     $output = $view->preview();
     $output = drupal_render($output);
-    $this->drupalSetContent($output, 'internal://test-grid');
+    $this->drupalSetContent($output);
     if (!in_array($alignment, $this->alignmentsTested)) {
       $result = $this->xpath('//div[contains(@class, "views-view-grid") and contains(@class, :alignment) and contains(@class, :columns)]', array(':alignment' => $alignment, ':columns' => 'cols-' . $columns));
       $this->assertTrue(count($result), ucfirst($alignment) . " grid markup detected.");