How Thorough Are Most Probation Test?

I have a court date on the second and my P.O. called and told my mom her recommendation; Random drug tests and if I fail one, 90 Days in Secure Detention. I really, really do not want to go back there, and need to know some information. How thorough and sophisticated used in most test done by the probation office? I know, it really varies on where you're at and all that, but there has to be a majority. When I was arrested, they used some sort of dipstick(?) type thing and the results came out in about 5 minutes. I was wondering- how "sophisticated" and reliable are those tests? If that's the kind they used for my arrest, is it going to be the same thing for random tests? And since my P.O. is a female, can she have someone go in the bathroom with me?

Yeah, weed is all I do. Popped a few Xanax a week or so before I was arrested so that came up in my initial test, so idk, lol. But...I figured dilution was a last resort and that I could probably get some substitute piss. My only problem is Idk what to do to keep my bottle(a small shampoo bottle from a hotel) strapped to me, and how to keep it warm. I can pretty much figure out ways around everything else, like if someone's watching me, but those two things I really need help with.

Typically if it is probation they send it to a lab as opposed to the dipstick method. All my UA's get sent to a lab and about a week later I get the results from my P.O. And my P.O. is also female and she just sends one of the males in the office to watch me pee, so don't bank on the female thing.