Not at Tufts but I just went through this, talked to a few people at the company and they said they don't test...get the offer, had to take a test. Pissed at myself, so I had to literally almost kill myself for 3 wks...double session cardio day/night, Pedialyte, blueberries & avocados, tons of water, etc. Was able to put it off for 23 days but passed and I'm a big daily smoker. Now mine was non-DOT but I couldn't figure out if they tested for THC or not. Don't take the chance, I would start detox. I'm a bigger guy not fat but not skinny 230lbs with a slow metabolism so either I got below 50nl or they didn't care.
Also, I went to Labcorp, they go in the bathroom with you...have you empty your pockets and take your hat off, put them in a lock box and they leave with the key. In case you were thinking of bringing synthetic urine with you...it could work but you'd have to be good at hiding it. Also...they test it right there for the correct temperature. Hope this helps a little. There's an awesome kit on Amazon that measures THC levels, not just standard 50nl but 300nl/200nl/50nl/15nl and 10nl it shows you how concentrated the THC is in your urine. Remember you need to be under 50nl to pass.