feat: send mailings over MailJet smtp in dedicated worker process

tests/MessageHandler/SendTeamerMailingHandlerTest.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\MessageHandler;
+
+use App\Message\SendTeamerMailing;
+use App\MessageHandler\SendTeamerMailingHandler;
+use App\Service\Teamer\TeamerMailingService;
+use PHPUnit\Framework\TestCase;
+
+class SendTeamerMailingHandlerTest extends TestCase
+{
+    public function testTheMailingIsHandedToTheServiceUnchanged(): void
+    {
+        $mailing = new SendTeamerMailing('Betreff', 'Nachricht', [
+            ['email' => '[email protected]', 'firstName' => 'Anna', 'lastName' => 'Berg', 'fullName' => 'Anna Berg'],
+        ]);
+
+        $service = $this->createMock(TeamerMailingService::class);
+        $service
+            ->expects($this->once())
+            ->method('sendMailing')
+            ->with($this->identicalTo($mailing))
+        ;
+
+        (new SendTeamerMailingHandler($service))($mailing);
+    }
+}