How to unit-test an action, when return type is ActionResult?

Question

I have written unit test for following action.

[HttpPost]
public ActionResult/*ViewResult*/ Create(MyViewModel vm)
{
    if (ModelState.IsValid)
    {
        //Do something...
        return RedirectToAction("Index");
    }

    return View(vm);
}

Test method can access Model properties, only when return type is ViewResult. In above code, I have used RedirectToAction so return type of this action can not be ViewResult.

In such scenario how do you unit-test an action?

Solution 1

So here is my little example:

public ActionResult Index(int id)
{
  if (1 != id)
  {
    return RedirectToAction("asd");
  }
  return View();
}

And the tests:

[TestMethod]
public void TestMethod1()
{
  HomeController homeController = new HomeController();
  ActionResult result = homeController.Index(10);
  Assert.IsInstanceOfType(result,typeof(RedirectToRouteResult));
  RedirectToRouteResult routeResult = result as RedirectToRouteResult;
  Assert.AreEqual(routeResult.RouteValues["action"], "asd");
}

[TestMethod]
public void TestMethod2()
{
  HomeController homeController = new HomeController();
  ActionResult result = homeController.Index(1);
  Assert.IsInstanceOfType(result, typeof(ViewResult));
}

Edit:
Once you verified that the result type is ViewResut you can cast to it:

ViewResult vResult = result as ViewResult;
if(vResult != null)
{
  Assert.IsInstanceOfType(vResult.Model, typeof(YourModelType));
  YourModelType model = vResult.Model as YourModelType;
  if(model != null)
  {
    //...
  }
}

Solution 2

Please note that

Assert.IsInstanceOfType(result,typeof(RedirectToRouteResult)); 

has been deprecated.

The new syntax is

Assert.That(result, Is.InstanceOf<RedirectToRouteResult>());