如何测试ASP MVC应用程序以获得基于用户的安全性？

I've been writing tests for my domain objects for some time now, but I'm still not quite sure how to go about testing for security in my web project. Certain users in certain environments can access certain properties of my models etc, but how would you go about testing this? Right now, I'm basing it on the current authenticated user, but how would I go about injecting a fake authentication provider?I've been writing tests for my domain objects f