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C# MVC How to test Cutom Model Validation

I have a custom attribute named: requiredIf. This attribute is related to a custom DataAnnotationsModelValidator, named RequiredIfValidator.

I declare this mapping in file Global.asax.cs :

DataAnnotationsModelValidatorProvider.RegisterAdapter( typeof( RequiredIfAttribute ), typeof( RequiredIfValidator ) );


On runtime it works fine :)

But I want to test via a unit test the validation of my model. Guess than we have the following

public class MyModel

public bool A get;set;

[RequiredIf ("A", true)]
public bool? B get;set;



This model is valid when A is false, and when A is true B need to set to true or false.

I try to test this validation with the following Unit Test:

var viewModel = new MyModel();
var context = new ValidationContext( viewModel, null, null );
var results = new List<ValidationResult>();
viewModel.A = false;
var isModelStateValid = Validator.TryValidateObject( viewModel, context, results, true );

Assert.IsFalse( isModelStateValid );


And the assertion failed. It's logic because my RequiredIfValidator is not setted. So my question is how can I set this custom validator to run my Unit Test?

Thanks,

1 Answer
1

I managed to get this working with the following extension method:

public static class ViewModelExtensions

public static IReadOnlyCollection<ValidationResult> GetValidationResults<T>(this T viewModel, Func<Type, object> serviceProvider = null)

var result = GetComponentValidationResults(viewModel, serviceProvider);

var modelValidationResults = GetModelValidationResults(viewModel);

return result
.Concat(modelValidationResults.ToValidationResults())
.ToList();


private static List<ValidationResult> GetComponentValidationResults<T>(T viewModel, Func<Type, object> serviceProvider)

var vc = new ValidationContext(viewModel);
if (serviceProvider != null)

vc.InitializeServiceProvider(serviceProvider);


var result = new List<ValidationResult>();
Validator.TryValidateObject(viewModel, vc, result, true);
return result;


private static IEnumerable<ModelValidationResult> GetModelValidationResults<T>(T model)

var modelMetadata = ModelMetadataProviders.Current.GetMetadataForType(() => model, typeof(T));

/* build a stub controller context */
var controllerContext = Fake.ControllerContext.Build();

var validator = ModelValidator.GetModelValidator(modelMetadata, controllerContext);
return validator.Validate(null);


private static IEnumerable<ValidationResult> ToValidationResults(this IEnumerable<ModelValidationResult> results)

return results.Select(r => r.ToValidationResult());


private static ValidationResult ToValidationResult(this ModelValidationResult result)

return new ValidationResult(result.Message, new result.MemberName);




This can be used like:

// arrange
var target = new MyViewModel();

// act
var actual = target.GetValidationResults(StubServiceProvider);

// assert
/* Assertions for whatever the expected validation failure might be */


Note:

Fake.ControllerContext.Build()

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