How can I test ModelState?

Question

How can I test Controller.ViewData.ModelState? I would prefer to do it without any mock framework.

Answer 1

//[Required]
//public string Name { get; set; }
//[Required]
//public string Description { get; set; }

ProductModelEdit model = new ProductModelEdit() ;
//Init ModelState
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 );
ProductController.ModelState.Clear();
ProductController.ModelState.Merge(modelBinder.ModelState);

ViewResult result = (ViewResult)ProductController.CreateProduct(null,model);
Assert.IsTrue(result.ViewData.ModelState["Name"].Errors.Count > 0);
Assert.True(result.ViewData.ModelState["Description"].Errors.Count > 0);
Assert.True(!result.ViewData.ModelState.IsValid);