I'd say that 3 years is a very poor lifespan for a fluoro ballast. I find plenty of old fluorescent fittings in this area which are 30+ years old and still on their original ballast.
Admittedly though, the modern ones don't seem to have the longevity of the old types.
You can check continuity with a regular ohmmeter, and use a megger to check for insulation faults. Testing for shorted turns requires more sophisticated equipment than that found in the average field electrical kit.