independent Async(callback style) testing framework C# (.net 3.5)

I Want to create some end to end tests for my unity3d multiplayer game which is using gamesparks as it's multiplayer "server".

The gamesparks API is driven by callback style async. I want to create some interaction scenarios with the "server" and verify some gamesparks responses but I need a framework compatible with unity3d .net 3.5 (I think it is).

Any advice would be greatly appreciated (some already built async testing framework without tasks or async keyword ). I was looking for something like jasmine for javascript but didn't find any.

I also asked this question here : http://ift.tt/1AknLqM