I think it's wrong, but of course there's grey areas and unclear situations.
The reason why I think it's wrong is because you are enabling a cheater directly. It comes down to an individual and what they believe in. If you are helping another person cheat, then you are helping another person cheat, that's all. It depends on whether you think it's moral or not.
For myself, yeah it's immoral. But then again, I don't think cheating is a bigger deal as most people think. Sex is often confused with love, and that's what causes the bigger problem. The betrayal of trust is from broken expectations. People put far more stock in a simple act of pleasure.
Honestly though, how would you feel about the person that slept with your significant other. Would you be all forgiving and say "Oh, that's okay, they weren't the one that actually cheated. It was all my partner's fault." Definately not. You'd be angry with them both, because they were both involved in the act.
In the test situation, being the other person is being the person that willingly shows their test to the other person. It's one thing to have someone cheat from you because they looked. It's a completely different action to show them your answers specifically so they can cheat. Conspiracy to commit cheating would be a good name for it them.
So yeah, it's immoral in my eyes. It's conspiracy to commit cheating.