There's a common misconception that Job is tested by "Satan" as we have come to understand him through our modern conceptions as the Cosmic enemy of God from the garden of Eden. But this is incorrect. The Hebrew text in Job is hasatan. The definite article "ha" before "satan" should be translated into English as "the satan", where the satan means adversary.
This entity, who enters the Divine Council as one of the "Sons of God" is unnamed but his role/function is defined by what the text calls him - the adversary.