Fixed mutating content type from RelatedPart to MultiPart

src/MailTracker.php

@@ -240,7 +240,7 @@ protected function createTrackers($message)
                             $newParts[] = $part;
                         }
                     }
-                    $message->setBody(new AlternativePart(...$newParts));
+                    $message->setBody(new (get_class($original_content))(...$newParts));
                 } else {
                     $original_html = $original_content->getBody();
                     if($original_content->getMediaSubtype() == 'html') {

tests/MailTrackerTest.php

@@ -241,7 +241,7 @@ public function testSendMessageWithRelatedPart()
             ->andReturn('random-hash');
 
         try {
-            Mail::send('email.embed-test', [], function ($message) use ($email, $name) {
+            Mail::send('email.embed-test', ['imagePath' => __DIR__ . '/email/example.png'], function ($message) use ($email, $name) {
                 $message->from('from@johndoe.com', 'From Name');
                 $message->sender('sender@johndoe.com', 'Sender Name');
 
@@ -256,8 +256,8 @@ public function testSendMessageWithRelatedPart()
 
                 $message->priority(3);
             });
-        } catch (Exception $e) {
-            // dd($e);
+        } catch (TransportException $e) {
+
         }
 
         $this->assertDatabaseHas('sent_emails', [

tests/email/embed-test.blade.php

@@ -6,6 +6,6 @@
 		This is a test!
 	</h1>
 	<p>
-		<img src="{{ $message->embed(base_path()) }}" />
+		<img src="{{ $message->embed($imagePath) }}" />
 	</p>
 </body>