Mock objects help you design and test the interactions between the objects in your programs. the jmock library:
* makes it quick and easy to define mock objects, so you don't break the
rhythm of programming.
* lets you precisely specify the interactions between your objects, reducing
the brittleness of your tests.
* works well with the autocompletion and refactoring features of your ide
* plugs into your favourite test framework
* is easy to extend.