This kind of goes into the whole research field of António Damásio on consciousness.
We can easily assess if a human is conscious from a medical point of view. But do we have a deterministic test to prove an abstract entity is conscious?
Well, we can for *some* of the 40 different definitions of the word.
But there are people who are misdiagnosed to be in a vegetative state who later wake up and report experiences from when they appeared so: https://en.wikipedia.org/wiki/Vegetative_state#Misdiagnoses
Are you conscious when you dream, or is it just a memory replayed by your waking mind? Or only when it's a lucid dream? Or are lucid dreams themselves just the illusion of consciousness?
What about when you sleepwalk?
What about hypnopompic and hypnogogic states?
What about chemically altered consciousness like blind drunk, stoned, tripping on LSD?
We can’t. We can infer, from what they say and whether they’re ambulatory, that they’re probably conscious. But we often get it wrong. Empirically, we aren’t that far ahead of Descartes.