How to mock ModelState.IsValid using the Moq framework?

Question

I'm checking ModelState.IsValid in my controller action method that creates an Employee like this:

[HttpPost] public virtual ActionResult Create(EmployeeForm employeeForm) {     if (this.ModelState.IsValid)     {         IEmployee employee = this._uiFactoryInstance.Map(employeeForm);         employee.Save();     }      // Etc. } 

I want to mock it in my unit test method using Moq Framework. I tried to mock it like this:

var modelState = new Mock<ModelStateDictionary>(); modelState.Setup(m => m.IsValid).Returns(true); 

But this throws an exception in my unit test case. Can anyone help me out here?

Answer 1

You don't need to mock it. If you already have a controller you can add a model state error when initializing your test:

// arrange _controllerUnderTest.ModelState.AddModelError("key", "error message");  // act // Now call the controller action and it will  // enter the (!ModelState.IsValid) condition var actual = _controllerUnderTest.Index(); 

Answer 2

The only issue I have with the solution above is that it doesn't actually test the model if I set attributes. I setup my controller this way.

private HomeController GenerateController(object model)     {         HomeController controller = new HomeController()         {             RoleService = new MockRoleService(),             MembershipService = new MockMembershipService()         };         MvcMockHelpers.SetFakeAuthenticatedControllerContext(controller);          // bind errors modelstate to the controller         var modelBinder = new ModelBindingContext()         {             ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(() => model, model.GetType()),             ValueProvider = new NameValueCollectionValueProvider(new NameValueCollection(), CultureInfo.InvariantCulture)         };         var binder = new DefaultModelBinder().BindModel(new ControllerContext(), modelBinder);         controller.ModelState.Clear();         controller.ModelState.Merge(modelBinder.ModelState);         return controller;     } 

The modelBinder object is the object that test the validity of the model. This way I can just set the values of the object and test it.