Considering that Islam teaches that Allah is creator and doer of evil because Allah created absolutely everything, including evil, and even does evil to people when he wills and at times when he is asked.
According to islam, Allah deceived those who saw Jesus on the cross by making them think he died on the cross when he was really switched with someone else who died in his place. This makes Allah the best of all deceivers. And it also makes Allah a liar about his own verse which says,
"No one will suffer for the sins of others". 17:15. Indeed, the other guy suffered for the sins of Jesus which was his blaspheming when he allowed others to believe he is God but never corrected them. (This is why Christianity is STILL the world's biggest religion.)
And being the best of all deceivers makes Allah Satan according to the Bible.
Allah and Satan are one- both good and evil at the same time.
So Satan is being tested by Allah all right because they are one and the same!