I've had occasion to use my ABS a lot
(track events, but quite a few times on the road as well), and never has the ABS failed to prevent a tire, any tire, from locking for more than a brief moment
Sounds weird...try out some of the tests mentioned here, or do what I do-bring it up to speed then simply mash the brakes. You'll know if you have ABS I assure you. However, presuming your ABS might be inoperative, be prepared to slide a bit when you nail the brakes...be careful