Testing COB's

Is there some way to test questionable COB's I'm new to growing and COB's. I was wondering if they can be tested with a volt meter or another way before mounting on the heat sinks. Any help would be appreciated.

Don't bother wasting your time trying to figure out a method of testing whether a questionable COB is any good...

Far better to go with one that is... Bridgelux - Citizen - Cree all spring to mind