ASP.NET MVC Controller post method unit test: ModelState.IsValid always true

Question

I have written my first unit tests for an ASP.NET MVC web application. All works fine and it is giving me valuable information, but I can't test errors in the view model. The ModelState.IsValid is always true, even when some values are not filled in (empty string or null).

I have read already that the model validation happens when the posted data is mapped to the model and you need to write some code to do the model verification yourself:

• Geek With Blogs
• How can I test ModelState?

I have tried the three examples provided in the linked webpages, but it seems not to work for me.

Some code:

My viewmodel

...
[Required(ErrorMessageResourceName = "ErrorFirstName", ErrorMessageResourceType = typeof(Mui))]
[MaxLength(50)]
[Display(Name = "Firstname", ResourceType = typeof(Mui))]
public string FirstName { get; set; }
...

The controller

...
 [HttpPost]
    public ActionResult Index(POSViewModel model)
    {
        Contract contract = contractService.GetContract(model.ContractGuid.Value);

        if (!contract.IsDirectDebit.ToSafe())
        {
            ModelState.Remove("BankName");
            ModelState.Remove("BankAddress");
            ModelState.Remove("BankZip");
            ModelState.Remove("BankCity");
            ModelState.Remove("AccountNr");
        }

        if (ModelState.IsValid)
        {
            ...

            contractValidationService.Create(contractValidation);
            unitOfWork.SaveChanges();

            return RedirectToAction("index","thanks");
        }
        else
        {
            return Index(model.ContractGuid.ToString());
        }
    }

My unit test

  posViewModel.FirstName = null;
  posViewModel.LastName = "";
 ...
 var modelBinder = new ModelBindingContext()
        {
            ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(() => posViewModel, posViewModel.GetType()),
            ValueProvider = new NameValueCollectionValueProvider(new System.Collections.Specialized.NameValueCollection(), CultureInfo.InvariantCulture)
        };
        var binder = new DefaultModelBinder().BindModel(new ControllerContext(), modelBinder);
        posController.ModelState.Clear();
        posController.ModelState.Merge(modelBinder.ModelState);

        ActionResult result = posController.Index(posViewModel);

        //Assert
        mockContractValidationService.Verify(m => m.Create(It.IsAny<ContractValidation>()), Times.Never);
        Assert.IsInstanceOfType(result, typeof(ViewResult));

On the view, I'm using unobtrusive JavaScript validation, and it works.

Answer 1

I found this solution: SO: Validation does not work when I use Validator.TryValidateObject combined with the solution @Kenneth provided:

[TestMethod]
    public void test_validation()
    {
        var sut = new POSViewModel();
        // Set some properties here
        var context = new ValidationContext(sut, null, null);
        var results = new List<ValidationResult>();
        TypeDescriptor.AddProviderTransparent(new AssociatedMetadataTypeTypeDescriptionProvider(typeof(POSViewModel), typeof(POSViewModel)), typeof(POSViewModel));

        var isModelStateValid = Validator.TryValidateObject(sut, context, results, true);

        // Assert here
    }

If you have a class library with all you resources in, don't forget to reference it in your test project.