DUDE. NO!

if they do alcohol testing you are basically fucked. there are several problems. first, there is a considerable amount of yeast in beer which would not be present in normal urine. secondly, unless the person giving you the drug test is a total dumbfuckingidiot, they are probably going to smell the alcohol in your piss. many times it is a doctor who performs the drug test--and they aren't stupid, they see it ALL.

lastly, the PH of the "urine" would be thrown off (i.e. not consistant with normal urine)...because beer has ethanol alcohol. obviously this will alter the PH of your urine, which is sometimes tested for in a standard lab urinalysis.

so basically you would be better off substituting with some Quick Fix rather than beer.