i was drug tested for 2 years thought i had it down could smoke a hit or 2 on friday and when wednesday rolls around i would be clean if i got tested untill ya i got kicked out because for some reason i smoked on thursday and wednesday dropped hot i guess is what i am saying is u will never be for sure but i suggest stoping a few hours before the test so your not dumping into the cup and ur levels are extra high i kinda think thats what happened to me.