View Model Validation

GivenAValidEmailAddressAndPassword.cs

public class GivenAValidEmailAddressAndPassword : ViewModelValidationSpecification
    {
        private TestViewModel viewModel;

        protected override void Given()
        {
            base.Given();

            this.viewModel = new TestViewModel
            {
                Email = "foo@bar.com",
                Password = "qwertyuiop"
            };
        }

        protected override void When()
        {
            base.ValidateViewModel(viewModel);
        }

        [Then]
        public void ThenTheModelShouldBeValid()
        {
            base.validationReport.Violations.Count().ShouldEqual(0);
        }
    }

TestController.cs

public ActionResult(TestViewModel viewModel)
{
  //validate
  
  if(!ModelState.IsValid)
      return(viewModel);
      
  //can also use addModelError where necessary
  ModelState.AddModelError("","Some Other Error that i wanted to add");
}

TestViewModel.cs

public sealed class TestViewModel
{
    public string Email { get; set; }
    public string Password { get; set; }
    public string ConfirmPassword { get; set; }
}

TestViewModelValidator.cs

public sealed class TestViewModelValidator : Validator<TestViewModel>
{
    protected override void Rules()
    {
        Ensure(x => x.Email.IsNotNullOrEmpty()).And(()=>
            Ensure(x => x.Email.IsAValidEmailAddress()));

        Ensure(x => x.Password.IsNotNullOrEmpty()).And(() => 
            Ensure(x => x.ConfirmPassword.IsEqualTo(x.Password)));
    }
}

view.cshtml

<!-- View infomation can be added as overloads in the html helpers, this keeps view logic where it belongs -->

@html.LabelFor(model => model.Email,"My Email Address label")
@html.TexboxFor(model => model.Email)
@html.ValidationMessageFor(model => model.Email,"My Custom Error Message if i dont like the default")