public void acknowledge_RESULT_OK()
        {
            // arrange
            var key = "test_key";

            _storageService.Add(key, "whatever object", null);
            Guid faceId          = Guid.NewGuid();
            Guid personId        = Guid.NewGuid();
            var  faceServiceMock = new Mock <IFaceServiceClient>();
            var  obj             = new FaceController(Services.GetRequiredService <IHostingEnvironment>(), faceServiceMock.Object, _storageService);

            // act
            var result = obj.Acknowledge(key);

            // assert
            var storageObject = _storageService.Get(key);

            Assert.Null(storageObject);
        }