that sucks, i had to take a dug assessment test one time, they ask you questions about your drug use and all that jazz, took about an hour. I didn't think i had a problem but 'parently they did so i had to take alcohol/drug classes.....boring.
if you have the same thing as i did, no matter what you say you'll have to take some further class or shit after your test, but they are a joke so feel free to go blazed outta your mind. Just don't show up drunk if they think you're drunk or on drugs they kick you out. and then you have to retake it which costs more money.