When will an AI first pass a long, informed, adversarial Turing test?

The Turing test is,

a test of a machine's ability to exhibit intelligent behavior equivalent to, or indistinguishable from, that of a human. Turing proposed that a human evaluator would judge natural language conversations between a human and a machine designed to generate human-like responses. The evaluator would be aware that one of the two partners in conversation was a machine, and all participants would be separated from one another.

Alan Turing's original paper was, unfortunately, quite vague about the setup of the test. Since he devised the imitation game, a number real-life Turing tests have been conducted under various conditions. One such example is the now-defunct Loebner Prize, which used to hold a yearly competition.