your inspector will not allow a full tub test? about the same thing. your stack is plugged, full of water.
never put a gage on it, but i figure a tub full of water is about the same head pressure as 9' of 2'' pipe
reason i like it. the overflow is tested, and you dont have to pull hoses and go on the roof [i'm lazy]
ya'll need to talk to your inspectors,
I had one in colorado, that came right out and said, dont give a damn what the code says, hook that dishwasher to the disposal and loop the hose!!!!
BUT..hes pet peeve was caulk around the toilet. he would throw his ID on the floor, if he could push it under the toilet with the toe of his boot
red tag