Not only did Job not have a covenant with Got but had no idea who or what the devil was.There was a very limited knowledge about him in the old covenant.Got dealt with him though as the people allowed him to.Satan does have a right to be here and have authority in the earth because of Adam's sin.
The new testement believer is a child of God and has authority over him and it's the same that Jesus had when he was on earth. Romans 8:16 and 17 says the Spirit itself beareth witness with our spirit, that we are the children of God:
And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together. Also James 4:7 says Submit yourselves therefore to God. Resist the devil, and he will flee from you. Eph 3:27 says neither give place to the devil.
So to say that we have to go through the same thing that Job did is a slap in the face of Jesus.