cranberry juice along with green tea, beer, and coffee are no different than water apart from the fact that they are Diuretics-they increase the rate of urination.
D - diuretic
A diuretic is defined as any substance that increases urine output.
Caffeine, cranberry juice, and most "quick flush" herbal teas marketed
as "detoxifiers" are diuretics. 
Water,
though also effective in helping marijuana smokers "beat" the test, is
not a diuretic. Consuming diuretic fluids just prior to taking a urine
test dilutes the concentration of drug metabolites in the sample below
the threshold of detection. However, this effect is only temporarily.
Because marijuana’s 
primary metabolite
is fat soluble, consuming no amount of fluids – even diuretic fluids –
will permanently "flush" it out of one’s system. Once the short-term
effect of the diuretic wears off and the urine returns to its proper
concentration, cannabis metabolites will once again become readily
detectable to snooping drug screeners.
From NORML
but your real best bet is- with
W – water
Facing a drug test on short notice? Remember the phrase: "Just add
water." Drinking large quantities of water (e.g. 120 fluid oz) prior to
taking a urine test is the easiest, cheapest, and according to recent
testimony before Congress by the US Department of Health and Human
Services, still remains one of the most effective methods of beating a
urine test. In desperate circumstances, water may also be added
directly to a sample to dilute the specimen.
i had to play that game and was so fucking paranoid about testing in my own house, but luckily the rents were using the home drug test kits so i ended up peeing like a tiny amount in to add yellow, then filling the rest with water. Shit worked a couple times, but then they changed tests and the threshhold for thc amount was way lower. But whateva, glad you passed how much water you think you downed?