Question

It’s been a while since I did any MVC work, so I’m hopefully missing something. I’m trying to write a test and controller action to simply Edit a DTO named “Business”.

Controller Action:

[HttpPost]
public ActionResult Edit(string id, Business business)
{
    try
    {
        var model = _businessRepository.Get(id);

        if (model != null)
        {
            UpdateModel(model);

            if (ModelState.IsValid)
            {
                _businessRepository.Save(model);
            }
            else
            {
                return View(business);
            }
        }

        return RedirectToAction("Index");
    }
    catch
    {
        return View();
    }
}

Test:

[TestMethod]
public void Edit_Post_Action_Updates_Model_And_Redirects()
{
    // Arrange
    var mockBusinessRepository = new Mock<IBusinessRepository>();
    var model = new Business { Id = "1", Name = "Test" };
    var expected = new Business { Id = "1", Name = "Not Test" };

    // Set up result for business repository
    mockBusinessRepository.Setup(m => m.Get(model.Id)).Returns(model);
    mockBusinessRepository.Setup(m => m.Save(expected)).Returns(expected);
    var businessController = new BusinessController(mockBusinessRepository.Object);

    // Act
    var result = businessController.Edit(model.Id, expected) as RedirectToRouteResult;

    // Assert
    Assert.IsNotNull(result);
    Assert.AreEqual(result.RouteValues["action"], "Index");
    mockBusinessRepository.VerifyAll();
}

The line that it is giving an exception on, is the UpdateModel() in the controller. The exception details are:

“Value cannot be null. Parameter name: controllerContext”

Answer 1

I’ve managed to get what I wanted working by using Automapper instead of the UpdateModel.

I added in my automapper initialization (IPersistable is an interface for all my DTOs):

Mapper.CreateMap<IPersistable, IPersistable>().ForMember(dto => dto.Id, opt => opt.Ignore());

I then changed my controller action to:

[HttpPost]
public ActionResult Edit(string id, Business business)
{
    try
    {
        var model = _businessRepository.Get(id);

        if (model != null)
        {
            Mapper.Map(business, model);

            if (ModelState.IsValid)
            {
                _businessRepository.Save(model);
            }
            else
            {
                return View(business);
            }
        }

        return RedirectToAction("Index");
    }
    catch
    {
        return View();
    }
}

And changed my test to:

[TestMethod]
public void Edit_Post_Action_Updates_Model_And_Redirects()
{
    // Arrange
    var mockBusinessRepository = new Mock<IBusinessRepository>();
    var fromDB = new Business { Id = "1", Name = "Test" };
    var expected = new Business { Id = "1", Name = "Not Test" };

    // Set up result for business repository
    mockBusinessRepository.Setup(m => m.Get(fromDB.Id)).Returns(fromDB);
    mockBusinessRepository.Setup(m => m.Save(It.IsAny<Business>())).Returns(expected);
    var businessController = new BusinessController(mockBusinessRepository.Object) {ControllerContext = new ControllerContext()};

    //Act
    var result = businessController.Edit(fromDB.Id, expected) as RedirectToRouteResult;

    // Assert
    Assert.IsNotNull(result);
    Assert.AreEqual(result.RouteValues["action"], "Index");
    mockBusinessRepository.VerifyAll();
}