Eilon was correct – they made it easier! It’s trivial to test TempData now. This is all that’s needed to port the example from his earlier post to Preview 4 (thanks Ben): [TestFixture] public class HomeControllerTests { [Test] public void IndexSavesUserIDToTempDataAndRedirects() { var homeController = new HomeController(); homeController.TempData = new TempDataDictionary(); var result = homeController.Index(); [...]