On trunk (Magnolia 4.5) development we switched to JUnit 4. All new tests will be written in JUnit 4 style. Old tests can easily adapted when they're anyway touched - with one exception: base-tests that are subclassed in other modules should not be adapted occasionally as this would enforce to adapt all subclasses at the same time. This could be a huge effort that we don't want to do step by step but in a consolidated action.