Unit tests on MVC validation

Question

How can I test that my controller action is putting the correct errors in the ModelState when validating an entity, when I\'m using DataAnnotation validation in MVC 2 Previe

Answer 1

@giles-smith's answer is my preferred approach but the implementation can be simplified:

    public static void ValidateViewModel(this Controller controller, object viewModelToValidate)
    {
        var validationContext = new ValidationContext(viewModelToValidate, null, null);
        var validationResults = new List();
        Validator.TryValidateObject(viewModelToValidate, validationContext, validationResults, true);
        foreach (var validationResult in validationResults)
        {
            controller.ModelState.AddModelError(validationResult.MemberNames.FirstOrDefault() ?? string.Empty, validationResult.ErrorMessage);
        }
    }