JUnit Factory
JUnit Factory is an experimental test-generation service from Agitar Software.
The key to agility is being able to modify code easily and safely. The problem is that many Java applications are too brittle to extend and enhance easily. Attempts to fix or extend - no matter how carefully done - can introduce more bugs and more complexity.
With a full suite of characterization tests generated by JUnit Factory you can bring your legacy code under control.
To get more detail: http://www.junitfactory.com/