getStamps example

$stamps = [];
        if (null !== $this->dispatcher) {
            // The dispatched event here has `queued` set to `true`; the goal is NOT to render the message, but to let             // listeners do something before a message is sent to the queue.             // We are using a cloned message as we still want to dispatch the **original** message, not the one modified by listeners.             // That's because the listeners will run again when the email is sent via Messenger by the transport (see `AbstractTransport`).             // Listeners should act depending on the `$queued` argument of the `MessageEvent` instance.             $clonedMessage = clone $message;
            $clonedEnvelope = null !== $envelope ? clone $envelope : Envelope::create($clonedMessage);
            $event = new MessageEvent($clonedMessage, $clonedEnvelope, (string) $this->transport, true);
            $this->dispatcher->dispatch($event);
            $stamps = $event->getStamps();

            if ($event->isRejected()) {
                return;
            }
        }

        try {
            $this->bus->dispatch(new SendEmailMessage($message, $envelope), $stamps);
        } catch (HandlerFailedException $e) {
            foreach ($e->getNestedExceptions() as $nested) {
                if ($nested instanceof TransportExceptionInterface) {
                    

use Symfony\Component\Mime\Message;

class MessengerTransportListenerTest extends TestCase
{
    public function testNoMessengerTransportStampsByDefault()
    {
        $l = new MessengerTransportListener();
        $envelope = new Envelope(new Address('sender@example.com'), [new Address('recipient@example.com')]);
        $message = new Message(new Headers());
        $event = new MessageEvent($message, $envelope, 'smtp', true);
        $l->onMessage($event);
        $this->assertEmpty($event->getStamps());
    }

    public function testMessengerTransportStampViaHeader()
    {
        $l = new MessengerTransportListener();
        $envelope = new Envelope(new Address('sender@example.com'), [new Address('recipient@example.com')]);
        $headers = (new Headers())->addTextHeader('X-Bus-Transport', 'async');
        $message = new Message($headers);
        $event = new MessageEvent($message, $envelope, 'smtp', true);
        $l->onMessage($event);
        $this->assertCount(1, $event->getStamps());