There's a problem: an adequate mockery of sapience will be externally indistinguishable from genuine intelligence; it's the inaccessible internal world of the thinking thing that is its distinguishing characteristic.

In other words, beyond a certain point it's impossible to tell.

At the same time, it's just as impossible for me to know that another human is sentient, even if we meet face to face.

(So it's pretty much a moot point.)