How Is Race Defined and Tested?

I wonder how this objectively determines race:

Members of visible Minorities: persons, other than aboriginal peoples, who are non-Caucasian in race or non-white in colour

That is, if testing a court of law, how can anyone assert that I am any race? Perhaps I have an ancestor many years ago that was African. How would I know? Does that mean I am white? off-white? Exactly what is the objective test? Is it based on appearance? Is that subjective?

This is bullshit and we should stop it.