most drug tests from major corporations are BS and easy to pass
for instance, at kroger where i use to work, they had a "toothbrush" test (it was this thing that looked like a tooth brush and collected cheek cells i guess and spit) but it could be tricked
on top of only being accurate for about a week at tops, it could be fooled by mouth wash, drinking lots of soda and weird stuff, and also holding it in one spot in your mouth and not letting it move around a bunch thus avoiding it from getting a good sample (you will drool on it a bit if you try it like that, but its unavoidable)
i took it twice and let me tell you passed each time, someone i knew was blazed when they took it and passed (they send it to a lab)
also most corporations and business's test for "thc" but are really looking for harder drugs like pcp and meth and what not, they probably wont care (or at least i have never personally known anyone to be turned away for weed)