av-parser/tests/AvParser.UI.Tests/SettingsViewModelTests.cs

using AvParser.Core.Proxies;
using AvParser.Core.Settings;
using AvParser.Infrastructure.Storage;
using AvParser.UI.Services;
using AvParser.UI.Tests.Fakes;
using AvParser.UI.ViewModels;
using ReactiveUI.Primitives;
using ReactiveUI.Primitives.Concurrency;
using Serilog.Core;

namespace AvParser.UI.Tests;

public class SettingsViewModelTests
{
    /// <summary>Language service that applies nothing; these tests are not about translation.</summary>
    private sealed class FakeLocalizationService : ILocalizationService, IDisposable
    {
        private readonly ReactiveUI.Primitives.Signals.BehaviorSignal<AppLanguage> _current = new(AppLanguage.English);

        public AppLanguage Current => _current.Value;

        public IObservable<AppLanguage> Changes => _current;

        public void Apply(AppLanguage language) => _current.OnNext(language);

        public void Dispose() => _current.Dispose();
    }

    /// <summary>A picker that answers with whatever the test decided, without a window.</summary>
    private sealed class FakeFolderPicker : IFolderPicker
    {
        public string? Answer { get; set; }

        public string? StartedAt { get; private set; }

        public Task<string?> PickAsync(string title, string? startAt = null)
        {
            StartedAt = startAt;

            return Task.FromResult(Answer);
        }
    }

    private static (SettingsViewModel Page, FakeSettingsService Settings, FakeFolderPicker Picker) Build(
        AppSettings? settings = null,
        string? mediaDirectory = null
    )
    {
        var settingsService = new FakeSettingsService(settings);
        var picker = new FakeFolderPicker();
        var paths = new AppPaths(
            Path.Combine(Path.GetTempPath(), "AvParserTests", Guid.NewGuid().ToString("N")),
            mediaDirectory
        );

        var page = new SettingsViewModel(
            settingsService,
            new FakeThemeService(),
            paths,
            new LoggingLevelSwitch(),
            new ProxyPool([], new FakeProxyProbe(), new ProxyOptions()),
            new FakeLocalizationService(),
            picker,
            ImmediateSequencer.Instance
        );

        return (page, settingsService, picker);
    }

    [Fact]
    public void An_unset_media_root_shows_as_empty_so_the_watermark_can_speak()
    {
        var (page, _, _) = Build();

        page.MediaRootOverride.ShouldBeEmpty();
        page.MediaDirectoryNeedsRestart.ShouldBeFalse();
    }

    [Fact]
    public async Task Choosing_a_directory_records_it()
    {
        var chosen = Path.Combine(Path.GetTempPath(), "AvParserArchive");
        var (page, settings, picker) = Build();
        picker.Answer = chosen;

        await page.BrowseMediaDirectoryCommand.Execute().ToTask(TestContext.Current.CancellationToken);

        page.MediaRootOverride.ShouldBe(chosen);
        settings.Current.MediaRootOverride.ShouldBe(chosen);
    }

    [Fact]
    public async Task Cancelling_the_picker_changes_nothing()
    {
        var (page, _, picker) = Build();
        page.MediaRootOverride = "D:/archive";
        picker.Answer = null;

        await page.BrowseMediaDirectoryCommand.Execute().ToTask(TestContext.Current.CancellationToken);

        page.MediaRootOverride.ShouldBe("D:/archive");
    }

    [Fact]
    public async Task Resetting_clears_the_override_so_the_default_applies_again()
    {
        var (page, settings, _) = Build(new AppSettings { MediaRootOverride = "D:/archive" });

        page.MediaRootOverride.ShouldBe("D:/archive");

        await page.ResetMediaDirectoryCommand.Execute().ToTask(TestContext.Current.CancellationToken);

        page.MediaRootOverride.ShouldBeEmpty();
        settings.Current.MediaRootOverride.ShouldBeNull();
    }

    [Fact]
    public void A_root_that_differs_from_this_run_asks_for_a_restart()
    {
        // Paths are resolved before the container exists, so the change cannot take effect now.
        // Saying so beats writing somewhere other than the box claims.
        var (page, _, _) = Build(mediaDirectory: "D:/current-archive");

        page.MediaRootOverride = "D:/somewhere-else";

        page.MediaDirectoryNeedsRestart.ShouldBeTrue();
    }

    [Fact]
    public void A_root_that_matches_this_run_does_not()
    {
        var (page, _, _) = Build(mediaDirectory: "D:/current-archive");

        page.MediaRootOverride = "D:/current-archive/";

        page.MediaDirectoryNeedsRestart.ShouldBeFalse();
    }

    [Fact]
    public async Task Whitespace_is_treated_as_no_override_at_all()
    {
        var (page, settings, _) = Build(new AppSettings { MediaRootOverride = "D:/archive" });

        page.MediaRootOverride = "   ";
        await Task.Delay(50, TestContext.Current.CancellationToken);

        settings.Current.MediaRootOverride.ShouldBeNull();
        page.MediaDirectoryNeedsRestart.ShouldBeFalse();
    }
}