How does malcom test macduffs trustworthiness and loyalty?

Malcolm tests Macduff's trustworthiness and loyalty by pretending to be unworthy of the throne, claiming he is more corrupt than Macbeth. He lists his own vices and flaws, suggesting that he would be a worse ruler, to gauge Macduff's reaction. Macduff's vehement rejection of Malcolm's claims and his insistence on the need for a good king demonstrate his loyalty to Scotland and his commitment to justice, ultimately proving his trustworthiness as an ally against Macbeth. This test serves to confirm Macduff's integrity and resolve in the face of tyranny.