The World as a Test

Hi everyone,

One of the answers given to the question of the purpose of the world is that it is a temporary testing place for human beings before the afterlife: those who pass the test go to Jannah, and those who fail go to Jahannam. But why does Allah test mankind? The point of a test is to find out what the consequences will be, yet Allah already knows who will pass and who will fail. A related question is "Why does Allah create people who will fail anyway?" After all, He knows what their outcome will be, and what is the value of people suffering in the afterlife? In short, what is the point of the whole process of testing and assigning rewards and punishments?

Thank you in advance for taking the time to answer my questions.