Why does Amir constantly test Hassan's loyalty in The Kite Runner?

Amir is jealous over his father's attention to Hassan. He
does not understand why his father would treat the son of a servant so lavishly. Amir's
relationship with his father is a constant source of turmoil for him. He feels he never
receives the love and attention an only  son should have. Though Amir loves Hassan
deeply as a friend, some inner conflict that he is not even aware of leads him to
continually test Hassan's friendship. Afterwards, Amir is consumed with remorse for
having treated his friend so poorly. At the end of the novel, Amir will learn why this
conflict occurs. Hassan never waivers in his loyalty to Amir, despite the "testing" he
so frequently must endure.