Integration testing the mail dispatching in Laravel 5.1

When using the Mail facade in Laravel it is not so easy to test the output of the parsed mail template. Like http://stackoverflow.com/questions/31120567/unittesting-laravel-5-mail-using-mock I received the error Method Mockery_0__vendor_Swift_Mailer::getTransport() does not exist on this mock object. I ended up in listening to the mailer.sending event: