private async void BeUniqueByUsername_Update_Not_Exists()
        {
            Mock <IUserRepository> userRepository = new Mock <IUserRepository>();

            userRepository.Setup(x => x.ByUsername(It.IsAny <string>())).Returns(Task.FromResult <User>(null));
            var validator = new ApiUserRequestModelValidator(userRepository.Object);

            await validator.ValidateUpdateAsync(default(string), new ApiUserRequestModel());

            validator.ShouldNotHaveValidationErrorFor(x => x.Username, "A");
        }
        public async void LocationLocationId_Update_Valid_Reference()
        {
            Mock <IUserRepository> userRepository = new Mock <IUserRepository>();

            userRepository.Setup(x => x.LocationByLocationLocationId(It.IsAny <int>())).Returns(Task.FromResult <Location>(new Location()));

            var validator = new ApiUserRequestModelValidator(userRepository.Object);
            await validator.ValidateUpdateAsync(default(int), new ApiUserRequestModel());

            validator.ShouldNotHaveValidationErrorFor(x => x.LocationLocationId, 1);
        }