I’m currently working on my first ASP.NET MVC project. Naturally, I’m writing a good number of unit tests. I ran into a problem tonight with mocking Controller.User. Thankfully, someone at Stack Overflow had already asked a question about this. I took Bruno Reis’ answer:

var principal = new Moq.Mock<IPrincipal>();
// ... mock IPrincipal as you wish

var httpContext = new Moq.Mock<HttpContextBase>();
httpContext.Setup(x => x.User).Returns(principal.Object);
// ... mock other httpContext's properties, methods, as needed

var reqContext = new RequestContext(httpContext.Object, new RouteData());

// now create the controller:
var controller = new MyController();
controller.ControllerContext =
    new ControllerContext(reqContext, controller);

and I rewrote it using NUnit.Mocks and wrapped it into an implementation of HttpContextBase:

/// <summary>
/// A mock <see cref="HttpContextBase"/> that implements <see cref="HttpContextBase.User"/>.
/// </summary>
public class MockHttpContext : HttpContextBase
{
    private IPrincipal _user;

    public MockHttpContext()
    {
        DynamicMock identity = new DynamicMock(typeof (IIdentity));
        identity.ExpectAndReturn("get_Name", "testUser");

        DynamicMock user = new DynamicMock(typeof (IPrincipal));
        user.ExpectAndReturn("get_Identity", identity.MockInstance);

        _user = (IPrincipal) user.MockInstance;
    }

    public override IPrincipal User
    {
        get { return _user; }
        set { _user = value; }
    }
}

Now mocking Controller.User is as easy as this:

// create an instance of RequestContext using MockHttpContext.
RequestContext requestContext =
    new RequestContext(new MockHttpContext(), new RouteData());

// initialize the controller's ControllerContext
_controller.ControllerContext = new ControllerContext(requestContext, _controller);