Or maybe the Turing test is the right test but interpreted more literally: it is passed when the society that invented it genuinely believes it to have been passed. Hammering out the specific criteria ahead of time will only lead to frustration as it becomes clear that is not what the surrounding society actually holds as qualifying. The reason the goal posts move is that we fundamental misjudge what it is we find to be human intelligence, and given that we have a nasty habit of denying this quality to other humans, let alone animals, it's entirely possible we will never genuinely grant it to technical artefacts that we devise.