[Mailer] Make sure you can pass custom headers to Mailgun

Author: Nyholm

Tests/Transport/SendgridApiTransportTest.php

@@ -13,6 +13,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Mailer\Bridge\Sendgrid\Transport\SendgridApiTransport;
+use Symfony\Component\Mailer\Envelope;
 use Symfony\Component\Mime\Address;
 use Symfony\Component\Mime\Email;
 use Symfony\Contracts\HttpClient\HttpClientInterface;
@@ -149,4 +150,20 @@ public function testLineBreaksInEncodedAttachment()
 
         $mailer->send($email);
     }
+
+    public function testCustomHeader()
+    {
+        $email = new Email();
+        $email->getHeaders()->addTextHeader('foo', 'bar');
+        $envelope = new Envelope(new Address('[email protected]'), [new Address('[email protected]')]);
+
+        $transport = new SendgridApiTransport('ACCESS_KEY');
+        $method = new \ReflectionMethod(SendgridApiTransport::class, 'getPayload');
+        $method->setAccessible(true);
+        $payload = $method->invoke($transport, $email, $envelope);
+
+        $this->assertArrayHasKey('headers', $payload);
+        $this->assertArrayHasKey('foo', $payload['headers']);
+        $this->assertEquals('bar', $payload['headers']['foo']);
+    }
 }

Transport/SendgridApiTransport.php

@@ -104,7 +104,7 @@ private function getPayload(Email $email, Envelope $envelope): array
                 continue;
             }
 
-            $payload['headers'][$name] = $header->toString();
+            $payload['headers'][$name] = $header->getBodyAsString();
         }
 
         return $payload;