I thought you needed some kind of color coded strip to test piss in a cup. You have out smarted me. What good does piss in a cup do you if you have a hair test? None, unless you drink it, fag.
It lasts in your hair for an amount of 1-2 years, it's dumb to worry about that, considering its been only a week or so since it happened.
...if it lasts that long in your hair it wouldn't be dumb to worry about it... because you'd automatically fail.. which would make you be like OMG I NEED TO STOP 4EVA.. therefore worrying... or something like that