Running Junit Email Tests Without Emails Actually Going Out

Question

I want to run unit tests (Junit) on some model classes that typically will send emails confirming that things happened. Is there a mock email server that you can use with unit tests that will let you confirmation that your run tried to send an email without actually sending the emails out?

This seems like it would be a nice to have, just not sure I want to write my own. The app stack for the emailing aspect is Velocity+Spring, so it would be preferable if the test server can be pointed at by simply changing the applicationContext.xml file.

Answer 1

Phil Haack has a blog post about unit testing email sending, with a solution he coded around a freeware mail server.

Answer 2

I think the Mock JavaMail project is what you want.

Answer 3

My solution was to wrap the mail server in a class which takes all the config options and has a send() method. In my tests, I'd mock this class and override send() with something that saves the current parameters for the assert.

To test that the mail service itself works, send yourself a mail locally. Try hMail if you're on Windows.

Answer 4

Alternative answer: Dumbster is a fake SMTP server designed for testing against. It's written in Java.

Answer 5

I assume you're using Javamail and the problem is that javax.mail.Session is final and therefore can't be mocked.

Seems like others have suggested you simply define your own 'mail session' interface and create an implementation that uses Javamail. In your tests you then simply inject a mock while in 'real-world-mode' you inject the Javamail implementation.

Both JMock and EasyMock will support all the assertions you might want to make on the message you are sending and you testing is complete.

As an aside, I generally try to avoid any out-of-process calls from within unit tests - it kills you when you're running the test suite frequently, which normally translates into it being run less and that's code base issues start to occur.