minor #38474 [Notifier] Introduce NullMessage and remove transport setter in MessageInterface (jschaedl)

This PR was merged into the 5.x branch.

Discussion
----------

[Notifier] Introduce NullMessage and remove transport setter in MessageInterface

| Q             | A
| ------------- | ---
| Branch?       | 5.x
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | - <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT
| Doc PR        | - <!-- required for new features -->

Follow-up PR of https://github.com/symfony/symfony/pull/36479

Commits
-------

5701e89960 Introduce NullMessage and remove transport setter in MessageInterface

src/Symfony/Component/Notifier/Message/ChatMessage.php

@@ -77,7 +77,7 @@ final class ChatMessage implements MessageInterface
     /**
      * @return $this
      */
-    public function transport(?string $transport): MessageInterface
+    public function transport(?string $transport): self
     {
         $this->transport = $transport;
 

src/Symfony/Component/Notifier/Message/EmailMessage.php

@@ -102,7 +102,7 @@ final class EmailMessage implements MessageInterface
     /**
      * @return $this
      */
-    public function transport(string $transport): MessageInterface
+    public function transport(string $transport): self
     {
         if (!$this->message instanceof Email) {
             throw new LogicException('Cannot set a Transport on a RawMessage instance.');

src/Symfony/Component/Notifier/Message/MessageInterface.php

@@ -25,6 +25,4 @@ interface MessageInterface
     public function getOptions(): ?MessageOptionsInterface;
 
     public function getTransport(): ?string;
-
-    public function transport(string $transport): self;
 }

src/Symfony/Component/Notifier/Message/NullMessage.php

@@ -0,0 +1,47 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Notifier\Message;
+
+/**
+ * @author Jan Schädlich <jan.schaedlich@sensiolabs.de>
+ *
+ * @experimental in 5.2
+ */
+final class NullMessage implements MessageInterface
+{
+    private $decoratedMessage;
+
+    public function __construct(MessageInterface $message)
+    {
+        $this->decoratedMessage = $message;
+    }
+
+    public function getRecipientId(): ?string
+    {
+        return $this->decoratedMessage->getRecipientId();
+    }
+
+    public function getSubject(): string
+    {
+        return $this->decoratedMessage->getSubject();
+    }
+
+    public function getOptions(): ?MessageOptionsInterface
+    {
+        return $this->decoratedMessage->getOptions();
+    }
+
+    public function getTransport(): ?string
+    {
+        return $this->decoratedMessage->getTransport() ?? 'null';
+    }
+}

src/Symfony/Component/Notifier/Message/SmsMessage.php

@@ -83,7 +83,7 @@ final class SmsMessage implements MessageInterface
     /**
      * @return $this
      */
-    public function transport(string $transport): MessageInterface
+    public function transport(string $transport): self
     {
         $this->transport = $transport;
 

src/Symfony/Component/Notifier/Transport/NullTransport.php

@@ -15,6 +15,7 @@ use Symfony\Component\EventDispatcher\Event;
 use Symfony\Component\EventDispatcher\LegacyEventDispatcherProxy;
 use Symfony\Component\Notifier\Event\MessageEvent;
 use Symfony\Component\Notifier\Message\MessageInterface;
+use Symfony\Component\Notifier\Message\NullMessage;
 use Symfony\Component\Notifier\Message\SentMessage;
 use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
@@ -34,9 +35,7 @@ class NullTransport implements TransportInterface
 
     public function send(MessageInterface $message): SentMessage
     {
-        if (null === $message->getTransport()) {
-            $message->transport((string) $this);
-        }
+        $message = new NullMessage($message);
 
         if (null !== $this->dispatcher) {
             $this->dispatcher->dispatch(new MessageEvent($message));

src/Symfony/Component/Notifier/Transport/Transports.php

@@ -57,8 +57,6 @@ final class Transports implements TransportInterface
         if (!$transport = $message->getTransport()) {
             foreach ($this->transports as $transportName => $transport) {
                 if ($transport->supports($message)) {
-                    $message->transport($transportName);
-
                     return $transport->send($message);
                 }
             }