Estoy usando una extensión de controlador, y traté de burlarme de ella usando FakeItEasy (v 1.7.4) de esta manera:

A.CallTo(() => controller.RenderView(A<string>.Ignored,A<object>.Ignored,null)).Returns("");

pero me sale este error:

System.NullReferenceException : Object reference not set to an instance of an object.
at System.Object.GetType()
at FakeItEasy.Creation.ProxyGeneratorSelector.MethodCanBeInterceptedOnInstance(MethodInfo method, Object callTarget, ref String failReason)
at FakeItEasy.Configuration.DefaultInterceptionAsserter.AssertThatMethodCanBeInterceptedOnInstance(MethodInfo method, Object callTarget)
at FakeItEasy.Configuration.FakeConfigurationManager.CallTo(Expression`1 callSpecification)