Who was really being tested by the Binding of Isaac

In The Fall of Hyperion (a space opera science fiction novel that I am currently listening to) the author, Dan Simmons, makes an interesting claim.  In the story of the Binding of Isaac, it was not Abraham, but God who was being tested. In the classic interpretation of the bible verse it is the faith of Abraham which God wished to plumb by commanding Abraham to sacrifice Isaac. Simmons, in the novel, claims something different. He says it is God who was being tested, by Abraham, to see if he was worthy to be the god of Abraham.