public async Task register_RESULT_OK()
        {
            // arrange - mocking IFormFile using a memory stream
            var           obj        = new FaceController(Services.GetRequiredService <IHostingEnvironment>(), Services.GetRequiredService <IFaceServiceClient>(), _storageService);
            string        sampleFile = Path.Combine(Directory.GetCurrentDirectory(), "data", "joe_family.jpg");
            ResponseModel uploadResult;

            using (var fs = new FileStream(sampleFile, FileMode.Open))
            {
                FormFile f = new FormFile(fs, 0, fs.Length, "file", fs.Name);
                var      uploadResultTemp = await obj.Upload(f);

                uploadResult = ((OkObjectResult)uploadResultTemp).Value as ResponseModel;
            }

            // act
            var registerResult = await obj.Register(uploadResult.Key, 1, "Helen");

            // assert
            var storageObject = _storageService.Get(uploadResult.Key);

            Assert.Null(storageObject);

            // redetect & reidentify
            string sampleFileNext = Path.Combine(Directory.GetCurrentDirectory(), "data", "joe_family.jpg");

            using (var fsNext = new FileStream(sampleFileNext, FileMode.Open))
            {
                FormFile fNext            = new FormFile(fsNext, 0, fsNext.Length, "file", fsNext.Name);
                var      uploadResultTemp = await obj.Upload(fNext);

                Assert.Equal("Helen", (((OkObjectResult)uploadResultTemp).Value as ResponseModel).Faces[1].Candidates[0].PersonName);
            }
        }