/**
  * After executing the message queue tests, restore the original queue interfaces.
  * @return void
  */
 function tearDownOnce()
 {
     // Remove any queue definitions that are set up by tests. Currently only 'default' is used.
     MessageQueue::remove_interface("default");
     // Restore each interface.
     foreach (self::$saved_interfaces as $name => $def) {
         MessageQueue::add_interface($name, $def);
     }
     parent::tearDownOnce();
 }