How long does mad hatter (spice) stay in your system?

Mad Hatter is a type of "spice", the potpourri they were selling legally that kids were smoking, but I was also told that it would show up as heroin in a drug test. One of my friends has a drug test tomorrow and the last time that he smoked it was this morning and he's also smoked it every night for the last week and a half. Pleasehelpppppp! (: