I should probably clarify myself here and draw a distinction between "mock objects" and "fake objects". Mock object = typically very lighweight throwaway object whose implementation may be written for a single test. Typically it does stuff like assert correct values are passed in etc. Fake object = A fake implementation of the interface or interfaces that typically can be re-used by many different tests. E.g. we could create a "fake group management layer" which takes the place of JGroups and allows us to test distributed destinations quickly and in vm. Or a fake database which just stores data in a map in memory - enough to run tests against. Or a fake MINA which just forwards request/responses from client to server calling the correct objects at the correct times. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4105485#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...