Mocking controller context in ASP.NET MVC

ControllerTestExtensions.cs

using System;
using System.Collections;
using System.Security.Principal;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
using Moq;

namespace SharpJS.Web.Testing
{
    public static class ControllerTestExtensions
    {
        public static TController WithContext<TController>
            (this TController controller)
            where TController : Controller
        {
            if (controller.ControllerContext == null)
            {
                var context  = new Mock<HttpContextBase>
                    { DefaultValue = DefaultValue.Mock }
                    .Object;

                Mock.Get(context)
                    .Setup(c => c.Items).Returns(new Hashtable());

                // More mocking how-to here:
                // http://blog.spontaneouspublicity.com/unit-testing-the-mvc4-account-controller

                controller.ControllerContext = new ControllerContext
                    (context, new RouteData(), controller);
            }
            return controller;
        }

        public static TController AsUser<TController>
            (this TController controller, params string[] roles)
            where TController : Controller
        {
            var identity  = new GenericIdentity("user@example.net", "test");
            var principal = new GenericPrincipal(identity, roles);
            controller.WithContext().HttpContext.User = principal;
            return controller;
        }
    }
}