Have Google ever heard of testing, and giving pre-release code to manufacturers?

Or as with all their other stuff, in sometimes permanent beta, do they prefer to test stuff in production? I'm starting to wonder if the reason Google don't publish an Android roadmap is because they just release stuff on random days, according to the CEO's horoscope that morning. Or maybe an algorithm based on coffee consumption at HQ. If coffee consumption suddenly drops, then coders are pulling fewer late nights, thus bugs must have been squashed. Therefore publish code.