We need a definition of consciousness first, which there may never be unanimous agreement on. After that, I suppose the best we can to is reverse engineer by way of observation and experiment: Something which reacts to stimuli in all the same ways as a conscious being can reasonably be presumed conscious, although I suspect it can never be known with certainty.

I post text here, often accompanied by images and sometimes video. People then clap or don't depending on whether they enjoy what I posted.