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(); }