public async Task NePostoji_KorektnoMenja()
        {
            var nalogIzBaze   = FinNalogHelper.NalogFromDb(callBase: false);
            var fakeNalogRepo = new Mock <IFinNalogRepository>();

            fakeNalogRepo.Setup(x => x.GetPostojeciAsync(TipNaloga.Izvodi, new DateTime(2018, 10, 20))).ReturnsAsync(null as FinNalogId);
            var nalogSvc = new FinNalogService(fakeNalogRepo.Object);

            await nalogSvc.IzmeniZaglavljeAsync(nalogIzBaze.Object, TipNaloga.Izvodi, new DateTime(2018, 10, 20), "opis new");

            nalogIzBaze.Verify(x => x.IzmeniZaglavlje(TipNaloga.Izvodi, new DateTime(2018, 10, 20), "opis new"));
        }
        public async Task VecPostoji_Greska()
        {
            var nalogIzBaze         = FinNalogHelper.NalogFromDb(callBase: false);
            var fakeNalogRepo       = new Mock <IFinNalogRepository>();
            var nalogIzBazeIdRandom = new Mock <FinNalogId>
            {
                CallBase = true
            };

            nalogIzBazeIdRandom.SetupGet(x => x.Id).Returns(Guid.NewGuid());
            fakeNalogRepo.Setup(x => x.GetPostojeciAsync(TipNaloga.UlazneFakture, new DateTime(2018, 10, 21))).ReturnsAsync(nalogIzBazeIdRandom.Object);

            var nalogSvc = new FinNalogService(fakeNalogRepo.Object);

            Func <Task> izmeni = async() => await nalogSvc.IzmeniZaglavljeAsync(nalogIzBaze.Object, TipNaloga.UlazneFakture, new DateTime(2018, 10, 21), "opis");

            await Assert.ThrowsAsync <KnjizenjeException>(izmeni);
        }