Those Mocking Libraries In Full

People call them frameworks, but the way i see it, they're libraries.

Details

Information correct as of 2011-06-12. Bold indicates a reason to seriously consider a particular library. I should really add columns for 'Mocks statics?', 'Mocks finals?', 'Strict expectations?', and various other things.

Library	First Release		Latest Release		Google Hits	Mocks Classes?
EasyMock	1.0	2003-08-17	3.0	2010-05-08	417k	✓
jMock	1.1.0	2007-03-27	2.5.1	2008-08-24	249k	✓ (with jMock Legacy)
JMockit	0.990	2009-10	0.999.9	2011-05-17	73.1k	✓
JMockLib (aka MockLib)	1.1.2	2005-05-08	3.1.1	2009-02-11	4.15k	?
Mockachino	0.1	2010-02-06	0.5.1	2011-01-21	2.34k	✓ (with Objenesis?)
Mockito	0.9	2008-01	1.8.5	2010-05-26	289k	✓
Moxie	0.3	2010-07-06	0.9.0	2010-11-01	?	✓
RMock	1.0.0	2005-06-04	2.0.0	2007-03-18	22.5k	✓
SevenMock	0.9	2007-11-10	2.1.0	2008-06-17	2.19k	✓

Also, check out Powermock, which is a third-party add-on which turbocharges other libraries.

BATTLEGRID!

vs	jMock	Mockito	Moxie
EasyMock	2009-01 2010-12-17	2010-12-17 2010-06-27 2010-11-01	2010-11-01
jMock		2010-10? 2010-12-17 2010-08-01	2010-11-01
JMockit		2010-11-05
Mockachino		2010-02-21
Mockito			2010-11-01

See also some general comparisons, both definitely worth reading:

2008-08-22 (EasyMock, jMock, JMockit, Mockito) - Mockito wins
2009-03-31 (EasyMock, jMock, JMockit, Mockito, rMock, SevenMock, Unitils) - EasyMock and Mockito win
2011-05-15 (EasyMock, jMock, JMockit, Mockito, Unitils; also with PowerMock) - JMockit propaganda, so no conclusion reported
2010-10-19 (Mockito, EarsyMock, Mockachino, jMock, JMockit, Unitils) - chickens out of drawing a conclusion

Family Tree

Most of these libraries were written as a response to the landscape of other libraries which existed at the time, in an attempt to improve on them. However, it does seem that most libraries were a response to some specific set of predecessors. Using a highly advanced guesswork-based process, i have determined that the predecessors of each library are:

Dynamock: original (Freeman, Mackinnon, Pryce, et al)
jMock: Dynamock
EasyMock: ?
Mockito: EasyMock
JMockit: EasyMock, jMock, Mockito
Mockachino: Mockito
Moxie: EasyMock, JMock, Mockito

If each library was successful at improving on its predecessors, then the only libraries which have not so far been improved on are JMockit, Mockachino, and Moxie.

Questions You Should Ask

And by you, i mean me.

Proxies or bytecode weaving (and via an agent or a classloader)?: Less important than it used to be. Bytecode-based libraries are more powerful, but might be more finicky to work with.
Are expectations strict or loose?: If the class under test calls a method on a mock which has not been expected, should that cause failure or not? This is to some extent a matter of taste. Rainsberger's opinion is worth reading.
Is testing modal?: With some libraries, you have to explicitly switch from the specification phase to the execution and verification phase.
Is final verification explicit?: Do you have to make some sort of nowVerifyAllExpectations() call at the end of your test? That's easy to forget.
Do mocks actually suck?: Some say so