ASP.NET MVC: Mock controller.Url.Action

Question

Urls for menus in my ASP.NET MVC apps are generated from controller/actions. So, they call

controller.Url.Action(action, controller)

Now, how do I make this work in unit tests? I use MVCContrib successfully with

var controller = new TestControllerBuilder().CreateController<OrdersController>();

but whatever I try to do with it I get controller.Url.Action(action, controller) failing with NullReferenceException because Url == null.

Update: it's not about how to intercept HttpContext. I did this in several ways, using MVCContrib, Scott Hanselman's example of faking, and also the one from http://stephenwalther.com/blog/archive/2008/07/01/asp-net-mvc-tip-12-faking-the-controller-context.aspx. This doesn't help me because I need to know WHAT values to fake... is it ApplicationPath? How do I set it up? Does it need to match the called controller/action? That is, how do Url.Action works and how do I satisfy it?

Also, I know I can do IUrlActionAbstraction and go with it... but I'm not sure I want to do this. After all, I have MVCContrib/Mock full power and why do I need another abstraction.

Answer 1

Here's how you could mock UrlHelper using MvcContrib's TestControllerBuilder:

var routes = new RouteCollection();
MvcApplication.RegisterRoutes(routes);
HomeController controller = CreateController<HomeController>();

controller.HttpContext.Response
    .Stub(x => x.ApplyAppPathModifier("/Home/About"))
    .Return("/Home/About");

controller.Url = new UrlHelper(
    new RequestContext(
        controller.HttpContext, new RouteData()
    ), 
    routes
);
var url = controller.Url.Action("About", "Home");
Assert.IsFalse(string.IsNullOrEmpty(url));