Unit test dependencies for an ASP.NET MVC 3 ViewResult subclass

Question

I'm creating a really simple ViewResult subclass called JavaScriptViewResult that, when executing, calls the base implementation and then sets the Content-Type of the response to text/javascript. In trying to unit test this class, I'm running across a slew of difficulties fulfilling all of the dependencies of the ASP.NET MVC stack.

Here is what my unit test, which uses Rhino, looks like so far:

[TestMethod]
public void TestExecuteAction()
{
    var request = MockRepository.GenerateMock<HttpRequestBase>();
    request.Expect(m => m.Url).Return(new Uri("/Test/JavaScript", UriKind.Relative));

    var httpContext = MockRepository.GenerateMock<HttpContextBase>();
    httpContext.Expect(m => m.Request).Return(request);

    var controller = MockRepository.GenerateMock<ControllerBase>();

    var virtualPathProvider = MockRepository.GenerateMock<VirtualPathProvider>();

    var routeCollection = new RouteCollection(virtualPathProvider);
    routeCollection.MapRoute("FakeRoute", "Test/JavaScript", new { controller = "Test", action = "JavaScript" });
    var routeData = routeCollection.GetRouteData(httpContext);

    var context = new ControllerContext(httpContext, routeData, controller);

    var viewResult = new JavaScriptViewResult();
    viewResult.ExecuteResult(context);

    Assert.AreEqual("text/javascript", context.HttpContext.Response.ContentType);
}

The latest exception when running the test is a NullReferenceException deep within the bowels of System.Web.Routing.Route.GetRouteData(HttpContextBase httpContext).

How do I set up all of the dependencies for executing a ViewResult? Are there any techniques for making this simpler? Alternately, is there a different way I can utilize the MVC view engine to generate JavaScript that will set the proper Content-Type for the response?

Answer 1

I figured out how to meet the minimum requirements of ViewResult. One problem I was encountering was mocking the process of finding the view. This was avoidable by ensuring that the View property of my object was populated. Here is my working test:

[TestMethod]
public void TestExecuteAction()
{
    var response = MockRepository.GenerateStub<HttpResponseBase>();
    response.Output = new StringWriter();

    var httpContext = MockRepository.GenerateMock<HttpContextBase>();
    httpContext.Expect(m => m.Response).Return(response);

    var routeData = new RouteData();
    routeData.Values.Add("action", "FakeAction");

    var context = new ControllerContext(httpContext, routeData, MockRepository.GenerateMock<ControllerBase>());

    var viewResult = new JavaScriptViewResult();
    viewResult.View = MockRepository.GenerateMock<IView>();
    viewResult.ExecuteResult(context);

    Assert.AreEqual("text/javascript", context.HttpContext.Response.ContentType);
}