public async void Name_Update_length()
        {
            Mock <IBucketRepository> bucketRepository = new Mock <IBucketRepository>();

            bucketRepository.Setup(x => x.Get(It.IsAny <int>())).Returns(Task.FromResult(new Bucket()));

            var validator = new ApiBucketServerRequestModelValidator(bucketRepository.Object);
            await validator.ValidateUpdateAsync(default(int), new ApiBucketServerRequestModel());

            validator.ShouldHaveValidationErrorFor(x => x.Name, new string('A', 256));
        }
        private async void BeUniqueByExternalId_Update_Not_Exists()
        {
            Mock <IBucketRepository> bucketRepository = new Mock <IBucketRepository>();

            bucketRepository.Setup(x => x.ByExternalId(It.IsAny <Guid>())).Returns(Task.FromResult <Bucket>(null));
            var validator = new ApiBucketServerRequestModelValidator(bucketRepository.Object);

            await validator.ValidateUpdateAsync(default(int), new ApiBucketServerRequestModel());

            validator.ShouldNotHaveValidationErrorFor(x => x.ExternalId, Guid.Parse("8420cdcf-d595-ef65-66e7-dff9f98764da"));
        }