boyfriend using cocaine? drug test?

just a little background.. he has a history of cocaine use. i am 2 years sober, and we've been together for almost a year. about a month ago we were drinking and he went to the bathroom, when he came out he didn't realize he had residue left on his nose.

i was furious because i have worked extremely hard on my sobriety, but at the same time i was understanding and i know slip ups happen. he promised he wouldn't do it again and i believed him. since then i have found white powder left on the bathroom counters.

i called him out on it and he swore he had no idea and that i was being crazy for looking for that sort of thing. i let it slide because there wasn't enough to back up my claim.

so last night he stayed up until 4 am. i to went to check the bathroom counter and the residue was there again. i told him i thought he was doing coke and he got very defensive. would it be too much to ask him to take a drug test to prove he's not using?? i kinda already know he is, but i want to know for sure.