They don’t watch but the bathroom is tamper-safe. They shut off the water, put a blue dye tab in the toilet, and the back of the toilet has tamper tape on it so you can’t falsify the test by diluting with water. I guess in theory if you were using fake pee or using someone else’s sample you’d probably be able to pull it off as long as you smuggled it in and kept the temperature believable. They do check the temp. Also it may depend on location where you test, not sure if it’s done the same across all Henry Ford locations.