public void GoForwardMultipleTimesNavigatesForward()
        {
            // Prepare
            RegionNavigationJournal target = new RegionNavigationJournal();

            Mock<INavigateAsync> mockNavigationTarget = new Mock<INavigateAsync>();
            target.NavigationTarget = mockNavigationTarget.Object;

            Uri uri1 = new Uri("Uri1", UriKind.Relative);
            RegionNavigationJournalEntry entry1 = new RegionNavigationJournalEntry() { Uri = uri1 };

            Uri uri2 = new Uri("Uri2", UriKind.Relative);
            RegionNavigationJournalEntry entry2 = new RegionNavigationJournalEntry() { Uri = uri2 };

            Uri uri3 = new Uri("Uri3", UriKind.Relative);
            RegionNavigationJournalEntry entry3 = new RegionNavigationJournalEntry() { Uri = uri3 };

            target.RecordNavigation(entry1);
            target.RecordNavigation(entry2);
            target.RecordNavigation(entry3);

            mockNavigationTarget
                .Setup(x => x.RequestNavigate(uri1, It.IsAny<Action<NavigationResult>>()))
                .Callback<Uri, Action<NavigationResult>>((u, c) => c(new NavigationResult(null, true)));
            mockNavigationTarget
                .Setup(x => x.RequestNavigate(uri2, It.IsAny<Action<NavigationResult>>()))
                .Callback<Uri, Action<NavigationResult>>((u, c) => c(new NavigationResult(null, true)));
            mockNavigationTarget
                .Setup(x => x.RequestNavigate(uri3, It.IsAny<Action<NavigationResult>>()))
                .Callback<Uri, Action<NavigationResult>>((u, c) => c(new NavigationResult(null, true)));

            target.GoBack();
            target.GoBack();

            // Act
            target.GoForward();
            target.GoForward();

            // Verify
            Assert.IsTrue(target.CanGoBack);
            Assert.IsFalse(target.CanGoForward);
            Assert.AreSame(entry3, target.CurrentEntry);

            mockNavigationTarget.Verify(x => x.RequestNavigate(uri1, It.IsAny<Action<NavigationResult>>()), Times.Once());
            mockNavigationTarget.Verify(x => x.RequestNavigate(uri2, It.IsAny<Action<NavigationResult>>()), Times.Exactly(2));
            mockNavigationTarget.Verify(x => x.RequestNavigate(uri3, It.IsAny<Action<NavigationResult>>()), Times.Once());
        }
        public void GoForwardDoesNotChangeStateWhenNavigationFails()
        {
            // Prepare
            RegionNavigationJournal target = new RegionNavigationJournal();

            Mock<INavigateAsync> mockNavigationTarget = new Mock<INavigateAsync>();
            target.NavigationTarget = mockNavigationTarget.Object;

            Uri uri1 = new Uri("Uri1", UriKind.Relative);
            RegionNavigationJournalEntry entry1 = new RegionNavigationJournalEntry() { Uri = uri1 };

            Uri uri2 = new Uri("Uri2", UriKind.Relative);
            RegionNavigationJournalEntry entry2 = new RegionNavigationJournalEntry() { Uri = uri2 };

            Uri uri3 = new Uri("Uri3", UriKind.Relative);
            RegionNavigationJournalEntry entry3 = new RegionNavigationJournalEntry() { Uri = uri3 };

            target.RecordNavigation(entry1);
            target.RecordNavigation(entry2);
            target.RecordNavigation(entry3);

            mockNavigationTarget
                .Setup(x => x.RequestNavigate(uri1, It.IsAny<Action<NavigationResult>>(), null))
                .Callback<Uri, Action<NavigationResult>, NavigationParameters>((u, c, n) => c(new NavigationResult(null, true)));
            mockNavigationTarget
                .Setup(x => x.RequestNavigate(uri2, It.IsAny<Action<NavigationResult>>(), null))
                .Callback<Uri, Action<NavigationResult>, NavigationParameters>((u, c, n) => c(new NavigationResult(null, true)));
            mockNavigationTarget
                .Setup(x => x.RequestNavigate(uri3, It.IsAny<Action<NavigationResult>>(), null))
                .Callback<Uri, Action<NavigationResult>, NavigationParameters>((u, c, n) => c(new NavigationResult(null, false)));

            target.GoBack();

            // Act
            target.GoForward();

            // Verify
            Assert.IsTrue(target.CanGoBack);
            Assert.IsTrue(target.CanGoForward);
            Assert.AreSame(entry2, target.CurrentEntry);

            mockNavigationTarget.Verify(x => x.RequestNavigate(uri1, It.IsAny<Action<NavigationResult>>(), null), Times.Never());
            mockNavigationTarget.Verify(x => x.RequestNavigate(uri2, It.IsAny<Action<NavigationResult>>(), null), Times.Once());
            mockNavigationTarget.Verify(x => x.RequestNavigate(uri3, It.IsAny<Action<NavigationResult>>(), null), Times.Once());
        }