How do you test a guy to see if he really loves you?

For me, don't test anyone, if you value the relationship, one of my relationships failed because the girl wanted to test me. She insulted me to see how I would react, and that ended the relationship, even though she confessed it was a test.
But if you must test, allow time to test it for you naturally, because a bad or good guy character will manifest in a long run.