public async Task Call_ChallengesServiceCreateWhenNoFileIsAttached()
        {
            var tracksServiceFake     = new Mock <ITracksService>();
            var challengesServiceFake = new Mock <IChallengesService>();
            var mapperFake            = new Mock <IMappingProvider>();
            var fileSystemFake        = new Mock <IFileSystemService>();
            var fileUtilsFake         = new Mock <IFileUnits>();

            var controller = new ChallengeController(
                tracksServiceFake.Object,
                challengesServiceFake.Object,
                fileSystemFake.Object,
                mapperFake.Object,
                fileUtilsFake.Object);

            var vModelFake = new Mock <ChallengeAdministrationViewModel>();

            challengesServiceFake.Setup(
                x => x.Create(
                    It.IsAny <string>(),
                    It.IsAny <string>(),
                    It.IsAny <string>(),
                    It.IsAny <Language>(),
                    It.IsAny <double>(),
                    It.IsAny <int>(),
                    It.IsAny <IEnumerable <Test> >())).Verifiable();

            // Act
            await controller.Create(vModelFake.Object);

            // Assert
            challengesServiceFake.Verify(
                x => x.Create(
                    It.IsAny <string>(),
                    It.IsAny <string>(),
                    It.IsAny <string>(),
                    It.IsAny <Language>(),
                    It.IsAny <double>(),
                    It.IsAny <int>(),
                    It.IsAny <IEnumerable <Test> >()), Times.Once);
        }