I may or may not have been able to pass tests before by using the urine of a friend who doesn't smoke. An easy way to do it is to go buy some unlubricated condoms, have your friend pee in one and then tie it off at the top, and then you duct tape it to your inner thigh. This is important because the pee needs to stay at body temperature as most places test for the temperature too.

It's hard to pull off if it's a test where they monitor you going to the bathroom but for most employer pre-employement tests they just have you go into the bathroom unattended with the stipulation that you can't flush the toilet or they make you come back and do it again.