If Allah made all things, then Allah made evil. But for what purpose did Allah create evil?

If Allah made all things, then Allah made evil. But for what purpose did Allah create evil? Some say evil was created for humans to be "tested," but why is it necessary for humans to be "tested"? What is the purpose of this test? Can't free will exist without evil? Couldn't our actions be between a) a good choice b) an even better, more positive choice? What is the purpose of pain, evil and testing and why did Allah create these things?