Technically, I believe the court can order drug-testing at any point during the proceedings, given sufficient cause. Since this hearing is a result of your conviction, I don't think it very likely one will be arbitrarily administered unless, of course, you show up to the hearing obviously under the influence. (Note: this is only an opinion, NOT to be construed as legal advice.) If you're the least bit concerned about any test results, the obvious suggestion is to make certain they turn out negative, isn't it? Your probation office (or former attorney, if you had one) can answer a general policy question in your jurisdiction, but personally, I wouldn't recommend you take the chance even if it isn't standard policy. In my opinion, common sense dictates you do nothing, you say nothing (that means anywhere, including here) that remotely jeopardizes your position. Personally, I think certain details or specifics should remain between you and your attorney, if you have one.

Good luck.