xunit + mvc 6

gistfile1.cs

[Fact]
    public void Index_OneGet_ReturnsViewModel()
    {
        var sut= new HomeController();
        var httpContext = new Mock<HttpContext>().Object;
        var actionContext=new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
        sut.ActionContext=actionContext;
        
        ViewResult result= sut.Index() as ViewResult;
        Assert.True(result.ViewData.Model is StartPageViewModel);
    }
    
    
    
    
    using System;
using Microsoft.AspNet.Mvc;
using Web.Model;

namespace Web.Controllers
{
	public class HomeController : Controller
	{
	    public ActionResult Index()
	    {
	        return View("Index",new StartPageViewModel());
	    }
	}
}



error on xunit run:
 HomeTests.Index_OneGet_ReturnsViewModel [FAIL]
      System.NullReferenceException : Object reference not set to an instance of an object
      Stack Trace:
           at Microsoft.AspNet.Mvc.Controller.View (System.String viewName, System.Object model) [0x00000] in <filename unknown>:0 
           at Web.Controllers.HomeController.Index () [0x00000] in <filename unknown>:0 
           at HomeTests.Index_OneGet_ReturnsViewModel () [0x00000] in <filename unknown>:0 
           at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
           at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0 
Finished: test, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null