diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 810d4ea..5a12af6 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -326,7 +326,7 @@ protected function drupalCreateContentType(array $values = array()) {
     $status = $type->save();
     menu_router_rebuild();
 
-    $this->assertEqual($status, SAVED_NEW, t('Created content type %type.', array('%type' => $type->id())));
+    $this->assertEqual($status, SAVED_NEW, String::format('Created content type %type.', array('%type' => $type->id())));
 
     // Reset permissions so that permissions for this content type are
     // available.
@@ -582,10 +582,10 @@ protected function drupalCreateRole(array $permissions, $rid = NULL, $name = NUL
     }
     $result = $role->save();
 
-    $this->assertIdentical($result, SAVED_NEW, t('Created role ID @rid with name @name.', array(
+    $this->assertIdentical($result, SAVED_NEW, String::format('Created role ID @rid with name @name.', array(
       '@name' => var_export($role->label(), TRUE),
       '@rid' => var_export($role->id(), TRUE),
-    )), t('Role'));
+    )), 'Role');
 
     if ($result === SAVED_NEW) {
       // Grant the specified permissions to the role, if any.
@@ -594,10 +594,10 @@ protected function drupalCreateRole(array $permissions, $rid = NULL, $name = NUL
         $assigned_permissions = entity_load('user_role', $role->id())->permissions;
         $missing_permissions = array_diff($permissions, $assigned_permissions);
         if (!$missing_permissions) {
-          $this->pass(t('Created permissions: @perms', array('@perms' => implode(', ', $permissions))), t('Role'));
+          $this->pass(String::format('Created permissions: @perms', array('@perms' => implode(', ', $permissions))), 'Role');
         }
         else {
-          $this->fail(t('Failed to create permissions: @perms', array('@perms' => implode(', ', $missing_permissions))), t('Role'));
+          $this->fail(String::format('Failed to create permissions: @perms', array('@perms' => implode(', ', $missing_permissions))), 'Role');
         }
       }
       return $role->id();
@@ -628,7 +628,7 @@ protected function checkPermissions(array $permissions, $reset = FALSE) {
     $valid = TRUE;
     foreach ($permissions as $permission) {
       if (!in_array($permission, $available)) {
-        $this->fail(t('Invalid permission %permission.', array('%permission' => $permission)), t('Role'));
+        $this->fail(String::format('Invalid permission %permission.', array('%permission' => $permission)), 'Role');
         $valid = FALSE;
       }
     }
@@ -851,7 +851,7 @@ protected function setUp() {
     if ($modules) {
       $modules = array_unique($modules);
       $success = \Drupal::moduleHandler()->install($modules, TRUE);
-      $this->assertTrue($success, t('Enabled modules: %modules', array('%modules' => implode(', ', $modules))));
+      $this->assertTrue($success, String::format('Enabled modules: %modules', array('%modules' => implode(', ', $modules))));
       $this->rebuildContainer();
     }
 
@@ -1340,14 +1340,14 @@ protected function parse() {
       $htmlDom = new \DOMDocument();
       @$htmlDom->loadHTML('<?xml encoding="UTF-8">' . $this->drupalGetContent());
       if ($htmlDom) {
-        $this->pass(t('Valid HTML found on "@path"', array('@path' => $this->getUrl())), t('Browser'));
+        $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(t('Parsed page successfully.'), t('Browser'));
+      $this->fail('Parsed page successfully.', 'Browser');
     }
 
     return $this->elements;
@@ -1595,7 +1595,7 @@ protected function drupalPostForm($path, $edit, $submit, array $options = array(
       }
       // We have not found a form which contained all fields of $edit.
       foreach ($edit as $name => $value) {
-        $this->fail(t('Failed to set field @name to @value', array('@name' => $name, '@value' => $value)));
+        $this->fail(String::format('Failed to set field @name to @value', array('@name' => $name, '@value' => $value)));
       }
       if (!$ajax && isset($submit)) {
         $this->assertTrue($submit_matches, format_string('Found the @submit button', array('@submit' => $submit)));
@@ -2278,7 +2278,7 @@ protected function getAllOptions(\SimpleXMLElement $element) {
    */
   protected function assertLink($label, $index = 0, $message = '', $group = 'Other') {
     $links = $this->xpath('//a[normalize-space(text())=:label]', array(':label' => $label));
-    $message = ($message ?  $message : t('Link with label %label found.', array('%label' => $label)));
+    $message = ($message ?  $message : String::format('Link with label %label found.', array('%label' => $label)));
     return $this->assert(isset($links[$index]), $message, $group);
   }
 
@@ -2304,7 +2304,7 @@ protected function assertLink($label, $index = 0, $message = '', $group = 'Other
    */
   protected function assertNoLink($label, $message = '', $group = 'Other') {
     $links = $this->xpath('//a[normalize-space(text())=:label]', array(':label' => $label));
-    $message = ($message ?  $message : t('Link with label %label not found.', array('%label' => $label)));
+    $message = ($message ?  $message : String::format('Link with label %label not found.', array('%label' => $label)));
     return $this->assert(empty($links), $message, $group);
   }
 
@@ -2330,7 +2330,7 @@ protected function assertNoLink($label, $message = '', $group = 'Other') {
    */
   protected function assertLinkByHref($href, $index = 0, $message = '', $group = 'Other') {
     $links = $this->xpath('//a[contains(@href, :href)]', array(':href' => $href));
-    $message = ($message ?  $message : t('Link containing href %href found.', array('%href' => $href)));
+    $message = ($message ?  $message : String::format('Link containing href %href found.', array('%href' => $href)));
     return $this->assert(isset($links[$index]), $message, $group);
   }
 
@@ -2354,7 +2354,7 @@ protected function assertLinkByHref($href, $index = 0, $message = '', $group = '
    */
   protected function assertNoLinkByHref($href, $message = '', $group = 'Other') {
     $links = $this->xpath('//a[contains(@href, :href)]', array(':href' => $href));
-    $message = ($message ?  $message : t('No link containing href %href found.', array('%href' => $href)));
+    $message = ($message ?  $message : String::format('No link containing href %href found.', array('%href' => $href)));
     return $this->assert(empty($links), $message, $group);
   }
 
@@ -2614,7 +2614,7 @@ protected function drupalSetSettings($settings) {
    */
   protected function assertUrl($path, array $options = array(), $message = '', $group = 'Other') {
     if (!$message) {
-      $message = t('Current URL is @url.', array(
+      $message = String::format('Current URL is @url.', array(
         '@url' => var_export($this->container->get('url_generator')->generateFromPath($path, $options), TRUE),
       ));
     }
@@ -2648,7 +2648,7 @@ protected function assertUrl($path, array $options = array(), $message = '', $gr
    */
   protected function assertRaw($raw, $message = '', $group = 'Other') {
     if (!$message) {
-      $message = t('Raw "@raw" found', array('@raw' => $raw));
+      $message = String::format('Raw "@raw" found', array('@raw' => $raw));
     }
     return $this->assert(strpos($this->drupalGetContent(), $raw) !== FALSE, $message, $group);
   }
@@ -2675,7 +2675,7 @@ protected function assertRaw($raw, $message = '', $group = 'Other') {
    */
   protected function assertNoRaw($raw, $message = '', $group = 'Other') {
     if (!$message) {
-      $message = t('Raw "@raw" not found', array('@raw' => $raw));
+      $message = String::format('Raw "@raw" not found', array('@raw' => $raw));
     }
     return $this->assert(strpos($this->drupalGetContent(), $raw) === FALSE, $message, $group);
   }
@@ -2759,7 +2759,7 @@ protected function assertTextHelper($text, $message = '', $group, $not_exists) {
       $this->plainTextContent = filter_xss($this->drupalGetContent(), array());
     }
     if (!$message) {
-      $message = !$not_exists ? t('"@text" found', array('@text' => $text)) : t('"@text" not found', array('@text' => $text));
+      $message = !$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, $group);
   }
@@ -2875,7 +2875,7 @@ protected function assertUniqueTextHelper($text, $message = '', $group, $be_uniq
    */
   protected function assertPattern($pattern, $message = '', $group = 'Other') {
     if (!$message) {
-      $message = t('Pattern "@pattern" found', array('@pattern' => $pattern));
+      $message = String::format('Pattern "@pattern" found', array('@pattern' => $pattern));
     }
     return $this->assert((bool) preg_match($pattern, $this->drupalGetContent()), $message, $group);
   }
@@ -2900,7 +2900,7 @@ protected function assertPattern($pattern, $message = '', $group = 'Other') {
    */
   protected function assertNoPattern($pattern, $message = '', $group = 'Other') {
     if (!$message) {
-      $message = t('Pattern "@pattern" not found', array('@pattern' => $pattern));
+      $message = String::format('Pattern "@pattern" not found', array('@pattern' => $pattern));
     }
     return $this->assert(!preg_match($pattern, $this->drupalGetContent()), $message, $group);
   }
@@ -2926,7 +2926,7 @@ protected function assertNoPattern($pattern, $message = '', $group = 'Other') {
   protected function assertTitle($title, $message = '', $group = 'Other') {
     $actual = (string) current($this->xpath('//title'));
     if (!$message) {
-      $message = t('Page title @actual is equal to @expected.', array(
+      $message = String::format('Page title @actual is equal to @expected.', array(
         '@actual' => var_export($actual, TRUE),
         '@expected' => var_export($title, TRUE),
       ));
@@ -2955,7 +2955,7 @@ protected function assertTitle($title, $message = '', $group = 'Other') {
   protected function assertNoTitle($title, $message = '', $group = 'Other') {
     $actual = (string) current($this->xpath('//title'));
     if (!$message) {
-      $message = t('Page title @actual is not equal to @unexpected.', array(
+      $message = String::format('Page title @actual is not equal to @unexpected.', array(
         '@actual' => var_export($actual, TRUE),
         '@unexpected' => var_export($title, TRUE),
       ));
@@ -3139,12 +3139,12 @@ protected function assertNoFieldByXPath($xpath, $value = NULL, $message = '', $g
   protected function assertFieldByName($name, $value = NULL, $message = NULL, $group = 'Browser') {
     if (!isset($message)) {
       if (!isset($value)) {
-        $message = t('Found field with name @name', array(
+        $message = String::format('Found field with name @name', array(
           '@name' => var_export($name, TRUE),
         ));
       }
       else {
-        $message = t('Found field with name @name and value @value', array(
+        $message = String::format('Found field with name @name and value @value', array(
           '@name' => var_export($name, TRUE),
           '@value' => var_export($value, TRUE),
         ));
@@ -3174,7 +3174,7 @@ protected function assertFieldByName($name, $value = NULL, $message = NULL, $gro
    *   TRUE on pass, FALSE on fail.
    */
   protected function assertNoFieldByName($name, $value = '', $message = '', $group = 'Browser') {
-    return $this->assertNoFieldByXPath($this->constructFieldXpath('name', $name), $value, $message ? $message : t('Did not find field by name @name', array('@name' => $name)), $group);
+    return $this->assertNoFieldByXPath($this->constructFieldXpath('name', $name), $value, $message ? $message : String::format('Did not find field by name @name', array('@name' => $name)), $group);
   }
 
   /**
@@ -3198,7 +3198,7 @@ protected function assertNoFieldByName($name, $value = '', $message = '', $group
    *   TRUE on pass, FALSE on fail.
    */
   protected function assertFieldById($id, $value = '', $message = '', $group = 'Browser') {
-    return $this->assertFieldByXPath($this->constructFieldXpath('id', $id), $value, $message ? $message : t('Found field by id @id', array('@id' => $id)), $group);
+    return $this->assertFieldByXPath($this->constructFieldXpath('id', $id), $value, $message ? $message : String::format('Found field by id @id', array('@id' => $id)), $group);
   }
 
   /**
@@ -3222,7 +3222,7 @@ protected function assertFieldById($id, $value = '', $message = '', $group = 'Br
    *   TRUE on pass, FALSE on fail.
    */
   protected function assertNoFieldById($id, $value = '', $message = '', $group = 'Browser') {
-    return $this->assertNoFieldByXPath($this->constructFieldXpath('id', $id), $value, $message ? $message : t('Did not find field by id @id', array('@id' => $id)), $group);
+    return $this->assertNoFieldByXPath($this->constructFieldXpath('id', $id), $value, $message ? $message : String::format('Did not find field by id @id', array('@id' => $id)), $group);
   }
 
   /**
@@ -3245,7 +3245,7 @@ protected function assertNoFieldById($id, $value = '', $message = '', $group = '
    */
   protected function assertFieldChecked($id, $message = '', $group = 'Browser') {
     $elements = $this->xpath('//input[@id=:id]', array(':id' => $id));
-    return $this->assertTrue(isset($elements[0]) && !empty($elements[0]['checked']), $message ? $message : t('Checkbox field @id is checked.', array('@id' => $id)), $group);
+    return $this->assertTrue(isset($elements[0]) && !empty($elements[0]['checked']), $message ? $message : String::format('Checkbox field @id is checked.', array('@id' => $id)), $group);
   }
 
   /**
@@ -3268,7 +3268,7 @@ protected function assertFieldChecked($id, $message = '', $group = 'Browser') {
    */
   protected function assertNoFieldChecked($id, $message = '', $group = 'Browser') {
     $elements = $this->xpath('//input[@id=:id]', array(':id' => $id));
-    return $this->assertTrue(isset($elements[0]) && empty($elements[0]['checked']), $message ? $message : t('Checkbox field @id is not checked.', array('@id' => $id)), $group);
+    return $this->assertTrue(isset($elements[0]) && empty($elements[0]['checked']), $message ? $message : String::format('Checkbox field @id is not checked.', array('@id' => $id)), $group);
   }
 
   /**
@@ -3293,7 +3293,7 @@ protected function assertNoFieldChecked($id, $message = '', $group = 'Browser')
    */
   protected function assertOption($id, $option, $message = '', $group = 'Browser') {
     $options = $this->xpath('//select[@id=:id]/option[@value=:option]', array(':id' => $id, ':option' => $option));
-    return $this->assertTrue(isset($options[0]), $message ? $message : t('Option @option for field @id exists.', array('@option' => $option, '@id' => $id)), $group);
+    return $this->assertTrue(isset($options[0]), $message ? $message : String::format('Option @option for field @id exists.', array('@option' => $option, '@id' => $id)), $group);
   }
 
   /**
@@ -3319,7 +3319,7 @@ protected function assertOption($id, $option, $message = '', $group = 'Browser')
   protected function assertNoOption($id, $option, $message = '', $group = 'Browser') {
     $selects = $this->xpath('//select[@id=:id]', array(':id' => $id));
     $options = $this->xpath('//select[@id=:id]/option[@value=:option]', array(':id' => $id, ':option' => $option));
-    return $this->assertTrue(isset($selects[0]) && !isset($options[0]), $message ? $message : t('Option @option for field @id does not exist.', array('@option' => $option, '@id' => $id)), $group);
+    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);
   }
 
   /**
@@ -3346,7 +3346,7 @@ protected function assertNoOption($id, $option, $message = '', $group = 'Browser
    */
   protected function assertOptionSelected($id, $option, $message = '', $group = 'Browser') {
     $elements = $this->xpath('//select[@id=:id]//option[@value=:option]', array(':id' => $id, ':option' => $option));
-    return $this->assertTrue(isset($elements[0]) && !empty($elements[0]['selected']), $message ? $message : t('Option @option for field @id is selected.', array('@option' => $option, '@id' => $id)), $group);
+    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);
   }
 
   /**
@@ -3371,7 +3371,7 @@ protected function assertOptionSelected($id, $option, $message = '', $group = 'B
    */
   protected function assertNoOptionSelected($id, $option, $message = '', $group = 'Browser') {
     $elements = $this->xpath('//select[@id=:id]//option[@value=:option]', array(':id' => $id, ':option' => $option));
-    return $this->assertTrue(isset($elements[0]) && empty($elements[0]['selected']), $message ? $message : t('Option @option for field @id is not selected.', array('@option' => $option, '@id' => $id)), $group);
+    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);
   }
 
   /**
@@ -3446,7 +3446,7 @@ protected function assertNoDuplicateIds($message = '', $group = 'Other', $ids_to
     foreach ($this->xpath('//*[@id]') as $element) {
       $id = (string) $element['id'];
       if (isset($seen_ids[$id]) && !in_array($id, $ids_to_skip)) {
-        $this->fail(t('The HTML ID %id is unique.', array('%id' => $id)), $group);
+        $this->fail(String::format('The HTML ID %id is unique.', array('%id' => $id)), $group);
         $status = FALSE;
       }
       $seen_ids[$id] = TRUE;
@@ -3492,7 +3492,7 @@ protected function constructFieldXpath($attribute, $value) {
   protected function assertResponse($code, $message = '', $group = 'Browser') {
     $curl_code = curl_getinfo($this->curlHandle, CURLINFO_HTTP_CODE);
     $match = is_array($code) ? in_array($curl_code, $code) : $curl_code == $code;
-    return $this->assertTrue($match, $message ? $message : t('HTTP response expected !code, actual !curl_code', array('!code' => $code, '!curl_code' => $curl_code)), $group);
+    return $this->assertTrue($match, $message ? $message : String::format('HTTP response expected !code, actual !curl_code', array('!code' => $code, '!curl_code' => $curl_code)), $group);
   }
 
   /**
@@ -3517,7 +3517,7 @@ protected function assertResponse($code, $message = '', $group = 'Browser') {
   protected function assertNoResponse($code, $message = '', $group = 'Browser') {
     $curl_code = curl_getinfo($this->curlHandle, CURLINFO_HTTP_CODE);
     $match = is_array($code) ? in_array($curl_code, $code) : $curl_code == $code;
-    return $this->assertFalse($match, $message ? $message : t('HTTP response not expected !code, actual !curl_code', array('!code' => $code, '!curl_code' => $curl_code)), $group);
+    return $this->assertFalse($match, $message ? $message : String::format('HTTP response not expected !code, actual !curl_code', array('!code' => $code, '!curl_code' => $curl_code)), $group);
   }
 
   /**
@@ -3631,7 +3631,7 @@ protected function verboseEmail($count = 1) {
     $mails = $this->drupalGetMails();
     for ($i = count($mails) -1; $i >= count($mails) - $count && $i >= 0; $i--) {
       $mail = $mails[$i];
-      $this->verbose(t('Email:') . '<pre>' . print_r($mail, TRUE) . '</pre>');
+      $this->verbose('Email:<pre>' . print_r($mail, TRUE) . '</pre>');
     }
   }