protected string GetErrorMessageForAttributeBasedConfigiguredItem <T>(T model, string propertyName) { // arrange Registry.Setup(x => x.GetModelPropertyMetadata(model.GetType(), propertyName)).Returns((ModelMetadataItem)null); // act var modelTemp = model; var metadata = Provider.GetMetadataForProperty(() => modelTemp, model.GetType(), propertyName); var validator = metadata.GetValidators(new ControllerContext()).First(); // assert return(validator.GetClientValidationRules().First().ErrorMessage); }