I've been working with Jakarta Cactus from inception with Vincent Massol early in 2000. It was the only solution to have a proper framework to test server-side components.
Classified in the integration unit test tools category, Cactus was essential in most of the large projects I worked on.
It allows integration tests of servlets (its first ability), EJBs, JSF components, Struts components.
Don't miss your chance to complete your test suite with Cactus, your application will be more robust than any other !