diff --git a/core/lib/Drupal/Core/Mail/MalPhpMail.php b/core/lib/Drupal/Core/Mail/MalPhpMail.php
deleted file mode 100644
index f55cebc..0000000
--- a/core/lib/Drupal/Core/Mail/MalPhpMail.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-
-/**
- * @file
- * Definition of Drupal\Core\Mail\MalPhpMail.
- */
-
-namespace Drupal\Core\Mail;
-
-/**
- * Defines a mail sending implementation that return false.
- *
- * This class is for running tests or for development.
- */
-class MalPhpMail extends PhpMail implements MailInterface {
-
-  /**
-   * Overrides Drupal\Core\Mail\PhpMail::mail().
-   */
-  public function mail(array $message) {
-    return FALSE;
-  }
-}
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserCreateFailMailTest.php b/core/modules/user/lib/Drupal/user/Tests/UserCreateFailMailTest.php
index abd53c5..d6cc63f 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserCreateFailMailTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserCreateFailMailTest.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Definition of Drupal\user\Tests\UserCreateFailMailTest.
+ * Contains Drupal\user\Tests\UserCreateFailMailTest.
  */
 
 namespace Drupal\user\Tests;
@@ -14,6 +14,9 @@
  */
 class UserCreateFailMailTest extends WebTestBase {
 
+  // Enable user_mail_failure_test module.
+  public static $modules = array('user_mail_failure_test');
+
   public static function getInfo() {
     return array(
       'name' => 'User create with failed mail function',
@@ -22,32 +25,25 @@ public static function getInfo() {
     );
   }
 
-  /**
-   * Create a user through the administration interface and ensure that it
-   * displays proper message when mail does not work.
-   */
+  // Test the create user administration page.
   protected function testUserAdd() {
     $user = $this->drupalCreateUser(array('administer users'));
     $this->drupalLogin($user);
 
-    // We stop mail function
-    $mail_system_variable = config('system.mail')->get('interface.default');
-    config('system.mail')->set('interface.default', 'Drupal\Core\Mail\MalPhpMail')->save();
-    // We create a user, notify the created user and fail to send email.
+    // Replace the mail functionality with a fake, malfunctioning service.
+    config('system.mail')->set('interface.default', 'Drupal\user_mail_failure_test\TestPhpMailFailure')->save();
+    // Create a user, but fail to send an email.
     $name = $this->randomName();
     $edit = array(
       'name' => $name,
       'mail' => $this->randomName() . '@example.com',
       'pass[pass1]' => $pass = $this->randomString(),
       'pass[pass2]' => $pass,
-      'notify' => true,
+      'notify' => TRUE,
     );
     $this->drupalPost('admin/people/create', $edit, t('Create new account'));
 
-    $this->assertText(t('Unable to send e-mail. Contact the site administrator if the problem persists.'),'Error message for disfunctional mail.');
-    $this->assertNoText(t('A welcome message with further instructions has been e-mailed to the new user @name.', array('@name' => $edit['name'])), 'Do not show welcome message');
-
-    // Set the old variable back.
-    config('system.mail')->set('interface.default', $mail_system_variable)->save();
+    $this->assertText(t('Unable to send e-mail. Contact the site administrator if the problem persists.'));
+    $this->assertNoText(t('A welcome message with further instructions has been e-mailed to the new user @name.', array('@name' => $edit['name'])));
   }
 }
diff --git a/core/modules/user/tests/modules/user_mail_failure_test/lib/Drupal/user_mail_failure_test/TestPhpMailFailure.php b/core/modules/user/tests/modules/user_mail_failure_test/lib/Drupal/user_mail_failure_test/TestPhpMailFailure.php
new file mode 100644
index 0000000..5ed8797
--- /dev/null
+++ b/core/modules/user/tests/modules/user_mail_failure_test/lib/Drupal/user_mail_failure_test/TestPhpMailFailure.php
@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\user_mail_failure_test\TestPhpMailFailure.
+ */
+
+namespace Drupal\user_mail_failure_test;
+
+use Drupal\Core\Mail\PhpMail;
+use Drupal\Core\Mail\MailInterface;
+
+/**
+ * Defines a mail sending implementation that return false.
+ *
+ * This class is for running tests or for development.
+ */
+class TestPhpMailFailure extends PhpMail implements MailInterface {
+
+  /**
+   * Overrides Drupal\Core\Mail\PhpMail::mail().
+   */
+  public function mail(array $message) {
+    return FALSE;
+  }
+}
diff --git a/core/modules/user/tests/modules/user_mail_failure_test/user_mail_failure_test.info.yml b/core/modules/user/tests/modules/user_mail_failure_test/user_mail_failure_test.info.yml
new file mode 100644
index 0000000..139a601
--- /dev/null
+++ b/core/modules/user/tests/modules/user_mail_failure_test/user_mail_failure_test.info.yml
@@ -0,0 +1,8 @@
+name: 'User mail failure test'
+description: 'Create situation of mail failure.'
+package: Testing
+version: VERSION
+core: 8.x
+dependencies:
+  - user
+hidden: true
diff --git a/core/modules/user/tests/modules/user_mail_failure_test/user_mail_failure_test.module b/core/modules/user/tests/modules/user_mail_failure_test/user_mail_failure_test.module
new file mode 100644
index 0000000..e69de29