private async void BeUniqueByName_Create_Not_Exists() { Mock <IAddressTypeRepository> addressTypeRepository = new Mock <IAddressTypeRepository>(); addressTypeRepository.Setup(x => x.ByName(It.IsAny <string>())).Returns(Task.FromResult <AddressType>(null)); var validator = new ApiAddressTypeRequestModelValidator(addressTypeRepository.Object); await validator.ValidateCreateAsync(new ApiAddressTypeRequestModel()); validator.ShouldNotHaveValidationErrorFor(x => x.Name, "A"); }