AtomUI/tests/AtomUI.Desktop.Controls.Tests/Primitives/CandidateListBehaviorTests.cs

using AtomUI.Desktop.Controls.Primitives;
using Avalonia;
using Avalonia.Controls;
using Avalonia.Headless;
using Avalonia.Input;
using Avalonia.Threading;
using Shouldly;
using Xunit;
using AvaloniaWindow = Avalonia.Controls.Window;

namespace AtomUI.Desktop.Controls.Tests.Primitives;

public class CandidateListBehaviorTests
{
    static CandidateListBehaviorTests()
    {
        AvaloniaTestApp.EnsureInitialized();
    }

    [Fact]
    public void Pointer_And_Keyboard_Navigation_Share_One_Active_Candidate()
    {
        var alpha = new AutoCompleteOption { Header = "Alpha", Content = "Alpha" };
        var beta  = new AutoCompleteOption { Header = "Beta", Content = "Beta" };
        var candidateList = new CandidateList
        {
            Width       = 240,
            Height      = 120,
            ItemsSource = new[] { alpha, beta }
        };
        object? committedItem = null;
        candidateList.Commit += (_, _) => committedItem = candidateList.SelectedItem;
        var window = Show(candidateList);

        try
        {
            var alphaContainer = GetContainer(candidateList, 0);
            var betaContainer  = GetContainer(candidateList, 1);

            MovePointerTo(alphaContainer, window);

            candidateList.CandidateSelectedItem.ShouldBeSameAs(alpha);
            alphaContainer.IsCandidateSelected.ShouldBeTrue();
            betaContainer.IsCandidateSelected.ShouldBeFalse();

            PressCandidateKey(candidateList, Key.Down);
            Dispatcher.UIThread.RunJobs();

            alphaContainer.IsPointerOver.ShouldBeTrue(
                "the regression requires the pointer to remain over the old candidate while keyboard navigation continues.");
            candidateList.CandidateSelectedItem.ShouldBeSameAs(beta);
            alphaContainer.IsCandidateSelected.ShouldBeFalse();
            betaContainer.IsCandidateSelected.ShouldBeTrue();

            PressCandidateKey(candidateList, Key.Enter);
            Dispatcher.UIThread.RunJobs();

            committedItem.ShouldBeSameAs(beta);
            candidateList.SelectedItem.ShouldBeNull(
                "the primitive clears its transient ListBox selection after notifying the owner.");
            candidateList.CandidateSelectedIndex.ShouldBe(-1);
            candidateList.CandidateSelectedItem.ShouldBeNull();
        }
        finally
        {
            window.Close();
        }
    }

    [Fact]
    public void Initial_Keyboard_Navigation_Skips_Disabled_Candidate()
    {
        var disabled = new AutoCompleteOption
        {
            Header    = "Disabled",
            Content   = "Disabled",
            IsEnabled = false
        };
        var available = new AutoCompleteOption { Header = "Available", Content = "Available" };
        var candidateList = new CandidateList
        {
            Width       = 240,
            Height      = 120,
            ItemsSource = new[] { disabled, available }
        };
        var window = Show(candidateList);

        try
        {
            MovePointerTo(GetContainer(candidateList, 0), window);
            candidateList.CandidateSelectedItem.ShouldBeNull();

            PressCandidateKey(candidateList, Key.Down);
            Dispatcher.UIThread.RunJobs();

            candidateList.CandidateSelectedItem.ShouldBeSameAs(available);
            GetContainer(candidateList, 0).IsCandidateSelected.ShouldBeFalse();
            GetContainer(candidateList, 1).IsCandidateSelected.ShouldBeTrue();
        }
        finally
        {
            window.Close();
        }
    }

    private static CandidateListItem GetContainer(CandidateList candidateList, int index)
    {
        var container = candidateList.ContainerFromIndex(index) as CandidateListItem;
        container.ShouldNotBeNull();
        return container;
    }

    private static void MovePointerTo(Control target, AvaloniaWindow window)
    {
        var point = target.TranslatePoint(
            new Point(target.Bounds.Width / 2, target.Bounds.Height / 2),
            window);
        point.ShouldNotBeNull();

        window.MouseMove(point.Value);
        Dispatcher.UIThread.RunJobs();
    }

    private static void PressCandidateKey(CandidateList candidateList, Key key)
    {
        candidateList.HandleKeyDown(new KeyEventArgs
        {
            RoutedEvent  = InputElement.KeyDownEvent,
            Source       = candidateList,
            Key          = key,
            PhysicalKey  = key switch
            {
                Key.Enter => PhysicalKey.Enter,
                Key.Up    => PhysicalKey.ArrowUp,
                Key.Down  => PhysicalKey.ArrowDown,
                _         => PhysicalKey.None
            },
            KeyModifiers = KeyModifiers.None
        });
    }

    private static AvaloniaWindow Show(Control content)
    {
        var window = new AvaloniaWindow
        {
            Width   = 360,
            Height  = 240,
            Content = content
        };
        window.Show();
        Dispatcher.UIThread.RunJobs();
        return window;
    }
}