On Codeception.com an tutorial has been posted showing you how to use PHPUnit to test emails - verifying that your application emails are being sent with the help of a third-party service.
So how do you check that your applications sends email correctly? It looks like dealing with emails is always a challenge. How would you verify that email message is formatted and delivered correctly, without actually sending them to your clients? That's the first question. And the second question is: how can we automate testing of emails? For both questions we have an answer.
To answer the first, they recommend using a service like Mailtrap or Mailcatcher (the one they use for the post) to receive the emails for evaluation. They help you get both PHPUnit and the popular Guzzle HTTP library installed to help with resting against Mailcatcher's REST API. The example test is also included, showing a few methods that connect to the API, get the most recent messages and clear the list when it's complete. Assertions like assertEmailIsSent, assertEmailHtmlContains and assertEmailSenderEquals show how to test the message results that come back for validity.