[5.8] Provide notification callback with Swift message

src/Illuminate/Notifications/Channels/MailChannel.php

@@ -137,6 +137,8 @@ protected function buildMessage($mailMessage, $notifiable, $notification, $messa
         if (! is_null($message->priority)) {
             $mailMessage->setPriority($message->priority);
         }
+
+        $this->runCallbacks($mailMessage, $message);
     }
 
     /**
@@ -225,4 +227,20 @@ protected function addAttachments($mailMessage, $message)
             $mailMessage->attachData($attachment['data'], $attachment['name'], $attachment['options']);
         }
     }
+
+    /**
+     * Run the callbacks for the message.
+     *
+     * @param  \Illuminate\Mail\Message  $mailMessage
+     * @param  \Illuminate\Notifications\Messages\MailMessage  $message
+     * @return $this
+     */
+    protected function runCallbacks($mailMessage, $message)
+    {
+        foreach ($message->callbacks as $callback) {
+            $callback($mailMessage->getSwiftMessage());
+        }
+
+        return $this;
+    }
 }

src/Illuminate/Notifications/Messages/MailMessage.php

@@ -73,6 +73,13 @@ class MailMessage extends SimpleMessage implements Renderable
      */
     public $rawAttachments = [];
 
+    /**
+     * The callbacks for the message.
+     *
+     * @var array
+     */
+    public $callbacks = [];
+
     /**
      * Priority level of the message.
      *
@@ -224,6 +231,19 @@ public function attachData($data, $name, array $options = [])
         return $this;
     }
 
+    /**
+     * Add a callback for the message.
+     *
+     * @param  callable  $callback
+     * @return $this
+     */
+    public function withSwiftMessage($callback)
+    {
+        $this->callbacks[] = $callback;
+
+        return $this;
+    }
+
     /**
      * Set the priority of this message.
      *

tests/Notifications/NotificationMailMessageTest.php

@@ -74,4 +74,16 @@ public function testReplyToIsSetCorrectly()
 
         $this->assertSame([['[email protected]', null], ['[email protected]', 'Test']], $message->replyTo);
     }
+
+    public function testCallbackIsSetCorrectly()
+    {
+        $callback = function () {
+            //
+        };
+
+        $message = new MailMessage;
+        $message->withSwiftMessage($callback);
+
+        $this->assertSame([$callback], $message->callbacks);
+    }
 }