public void WhenReadingImageThenKentekenIsReturned()
        {
            async Task payload()
            {
                // Arrange
                var logger        = Substitute.For <ILogger <PhotoController> >();
                var smartContract = Substitute.For <ISmartContract>();
                var ctrl          = new PhotoController(logger, smartContract);
                var url           = "https://blockathon.blob.core.windows.net/kentekens/kenteken.jpg";

                // Act
                await ctrl.DoAnalyzePhoto(url);

                // Assert
                smartContract.Received().Callout(Arg.Is <string>(c => c == "XK50HF"));
            }

            payload().Wait();
        }