How does drug testing work on the pretrial diversion program?

I jus found out I was approved for a pre-trial diversion program. I was unaware that I would be drug tested, unfortunately I have a heavy history of marijuana use. I will be drug tested on thursday and have a history of smoking about 4 times a day. I will NOT be smoking at all anymore now that I know I will be drug tested and it is necessary to get this cleared off my record, but I really need to get through this first drug test. Can anyone tell me how this works. Will this be a urine test? Will someone be watching me urinate? Are there any detox that work? PLEASE LET ME KNOW IF YOU HAVE EXPERIENCE!