Infinitest is an Eclipse/IntelliJ IDEA plug-in that
automatically runs unit tests after changes. "Whenever you make a change, Infinitest runs tests for you. It selects tests intelligently, and only runs the ones you need. It reports unit test failures like compiler errors, and provides additional information that helps you write better tests. " I hope it does that in the background. Licensing is unclear, but it looks like free beer at first glance.