It is a pretty common pattern to validate your Web Action model using ModelState.IsValid method. For example,
public async Task<UpdateUserProfileResponse> UpdateUser(UpdateUserProfileRequest user)
{
if (ModelState.IsValid)
{
// Valid Model, do your job
}
else
{
// Send response indicating invalid model
}
}
A pretty useful pattern, as it makes use of the DataAnnotations to validate and provide meaning messages. One question though that raises is, how do you unit test such a pattern ? The trick lies in emulating the ModelState. You could do with minimal code. For example,
protected void MockModelState<TModel,TController>(TModel model, TController controller) where TController: ControllerBase
{
var validationContext = new System.ComponentModel.DataAnnotations.ValidationContext(model, null, null);
var validationResults = new List<ValidationResult>();
Validator.TryValidateObject(model, validationContext, validationResults, true);
foreach (var validationResult in validationResults)
{
controller.ModelState.AddModelError(validationResult.MemberNames.First(), validationResult.ErrorMessage);
}
}
With that in place, you could now write Unit Test for your controller as the following
var userController = new UserController(Mapper, mockUserProfileService.Object, null, null);
MockModelState(request,userController);
var result = await userController.UpdateUser(request);
That’s all you need.
ByteLanguage.Net 