How does Malcolm test Macduff?

Apparently Malcolm says, that if he were king, he would

-sleep/rape everything female in Scotland

-steal the noble’s land and cut off their heads (this is supposed to be worse that the first one)

-plunge Scotland into hell

Macduff concedes the first two but says he will leave Scotland if the third should happen. Based upon his answers, Macduff passes Malcolm's test.