public function testNotifier()
      {  
         /** @var NotifierInterface $notifier */
         $firstNotification = new Notification('Hello World!', ['chat/slack']);
        $firstNotification->content("Symfony is awesome!");

        $notifier->send($firstNotification);

        $secondNotification = (new Notification('New urgent notification'))
            ->importance(Notification::IMPORTANCE_URGENT)
        ;
        $notifier->send($secondNotification);

                $this->assertNotificationCount(2);
        $first = 0;
        $second = 1;
        $this->assertNotificationIsNotQueued($this->getNotifierEvent($first));
        $this->assertNotificationIsNotQueued($this->getNotifierEvent($second));

        $notification = $this->getNotifierMessage($first);
        $this->assertNotificationSubjectContains($notification, 'Hello World!');
        $this->assertNotificationSubjectNotContains($notification, 'New urgent notification');
        $this->assertNotificationTransportIsEqual($notification,'slack');
        $this->assertNotificationTransportIsNotEqual($notification,'mercure');


        $notification = $this->getNotifierMessage($second);
        $this->assertNotificationSubjectContains($notification, 'New urgent notification');
        $this->assertNotificationSubjectNotContains($notification, 'Hello World!');
        $this->assertNotificationTransportIsEqual($notification,'mercure');
        $this->assertNotificationTransportIsNotEqual($notification,'slack');

  }