LlamaCasty/ytLive.Tests/ZoomFollowModeTests.cs

using System;
using System.IO;
using Xunit;
using ytLive.ViewModels;

namespace ytLive.Tests;

/// <summary>
/// Zoom box follow mode (creator ruling 2026-11-01): the Settings pill toggles between **Anchor**
/// — the capture stays on the clicked point, which is the default and the 2026-10-08 model — and
/// **Follow**, where dragging the box re-anchors the capture to the box centre so the magnifier
/// shows whatever it hovers over.
/// </summary>
// Shares the static MainViewModel.LayoutPathOverride with the sibling class; without a
// shared collection xUnit runs them in parallel and the two view models fight over one temp DB.
[Collection("MainViewModelLayoutPath")]
public class ZoomFollowModeTests
{
    private static MainViewModel NewVm(out string dbPath)
    {
        dbPath = Path.Combine(Path.GetTempPath(), $"llamacasty-zoom-{Guid.NewGuid():N}.db");
        MainViewModel.LayoutPathOverride = dbPath;
        return new MainViewModel();
    }

    [Fact]
    public void Anchor_is_the_default_and_dragging_leaves_the_capture_alone()
    {
        var vm = NewVm(out var dbPath);
        try
        {
            Assert.False(vm.ZoomFollowsBox);

            vm.ActivateZoom(1000, 500);
            var captureX = vm.ZoomState.CaptureX;

            vm.StartZoomMove(1000, 500);
            vm.UpdateZoomMove(1200, 700);

            Assert.Equal(captureX, vm.ZoomState.CaptureX);
        }
        finally
        {
            MainViewModel.LayoutPathOverride = null;
            try { File.Delete(dbPath); } catch (IOException) { }
        }
    }

    [Fact]
    public void Follow_moves_the_capture_with_the_box()
    {
        var vm = NewVm(out var dbPath);
        try
        {
            vm.ActivateZoom(1000, 500);
            var anchoredCaptureX = vm.ZoomState.CaptureX;

            vm.ZoomFollowsBox = true;
            vm.StartZoomMove(1000, 500);
            vm.UpdateZoomMove(1200, 700);

            Assert.NotEqual(anchoredCaptureX, vm.ZoomState.CaptureX);
            // The capture is half the box, centred on the box: box centre minus a quarter of it.
            var expected = Math.Clamp(
                vm.ZoomState.X + vm.ZoomState.Width / 2 - vm.ZoomState.Width / 4,
                0, 1920 - vm.ZoomState.Width / 2);
            Assert.Equal(expected, vm.ZoomState.CaptureX, 3);
        }
        finally
        {
            MainViewModel.LayoutPathOverride = null;
            try { File.Delete(dbPath); } catch (IOException) { }
        }
    }

    [Fact]
    public void The_choice_persists_in_settings()
    {
        // Persistence is the store's job, tested against the store directly: two live view models
        // in one process fight over the SQLite file and the frame pump, which is a property of the
        // fixture, not of the setting.
        var dbPath = Path.Combine(Path.GetTempPath(), $"llamacasty-zoom-{Guid.NewGuid():N}.db");
        try
        {
            using (var store = new ytLive.Services.LayoutStore(dbPath))
            {
                Assert.False(store.LoadZoomFollowBox());
                store.SaveZoomFollowBox(true);
            }

            using (var reopened = new ytLive.Services.LayoutStore(dbPath))
            {
                Assert.True(reopened.LoadZoomFollowBox());
                reopened.SaveZoomFollowBox(false);
            }

            using (var again = new ytLive.Services.LayoutStore(dbPath))
                Assert.False(again.LoadZoomFollowBox());
        }
        finally
        {
            try { File.Delete(dbPath); } catch (IOException) { }
        }
    }
}