"And the Lord said, ‘Who will entice Ahab to go up and fall at Ramoth-gilead?’ And one said this while another said that. 21"Then a spirit came forward and stood before the Lord and said, ‘I will entice him.’ 22"And the Lord said to him, ‘How?’ And he said, ‘I will go out and be a deceiving spirit in the mouth of all his prophets.’ Then He said, ‘You are to entice him and also prevail. Go and do so,’" (1 Kings 22:20-22).
Open theists like to say that God was ignorant of how the spirit would go and entice Ahab. But this is not necessarily so since God could simply have been asking this spirit so that it would publically say what it would do. God--as King in His spiritual kingdom--requires obedience of His subjects. God, like a king, inquires. In this case, it was not so God could learn but that the truth of the spirit's intent could be made public.
Contextually, Micaiah is relating a vision to Jehoshaphat, and it is in this vision that God asks the spirit what it will do. This is not necessarily literal as if God had to learn something.
Are there examples where God knows something yet asks a question as though He didn't know? Most definitely yes. In John 18:3-5 it says,
"Judas then, having received the Roman cohort and officers from the chief priests and the Pharisees, came there with lanterns and torches and weapons. 4Jesus therefore, knowing all the things that were coming upon Him, went forth, and said to them, “Whom do you seek?” 5They answered Him, “Jesus the Nazarene.” He said to them, “I am He.”
The text clearly states that Jesus knew all things. Therefore, Jesus knew exactly who they were coming for, yet He asked them, "Whom do you seek?" If we are to be consistent and interpret this verse as an open theist would, we would have to state that Jesus didn't know who they came for. Of course, this does not work since we can plainly see that Jesus knew all things.
- 1 Kings 22:20-22 is the declaration of a vision, and so it need not be taken literally.
- We see that Jesus, who knew all things, asked a question He knew the answer to in John 18:3-5. Therefore, 1 Kings 22:20-22 is where God asked a question He already knew the answer to as well.