Mock Object Libraries in Java

Question

Would anyone suggest a Mock library and provide the reasoning behind the pick?

I am looking to introduce one to the existing code base.

Thanks.

Answer 1

easymock. Reasons, from their site

'EasyMock provides Mock Objects for interfaces (and objects through the class extension) by generating them on the fly using Java's proxy mechanism. Due to EasyMock's unique style of recording expectations, most refactorings will not affect the Mock Objects. So EasyMock is a perfect fit for Test-Driven Development.'

Answer 2

This is the best comparison I've seen, of multiple Java mocking frameworks, including EasyMock and mockito.

http://www.sizovpoint.com/2009/03/java-mock-frameworks-comparison.html

It includes EasyMock, Mockito, jMock, SevenMock, JMockit, rMock, Unitils.

I used EasyMock first, but have moved to Mockito. Unit tests created with EasyMock were sometimes fragile and hard to debug. Mockito is easy, partly because it distinguishes between stubbing and verification. Here's a Mockito-oriented comparison of it and EasyMock: http://code.google.com/p/mockito/wiki/MockitoVSEasyMock.

Answer 3

My suggestion is JMockit. The project site has a lot of information (and hundreds of actual JUnit tests) comparing several Java mocking APIs (EasyMock, jMock, JMockit, Mockito, PowerMock, Unitils Mock), as well as an extensive feature comparison matrix.