oecs-sharp/Game.Blackjack.Tests/SnapshotTests.cs

using FluentAssertions;
using Game.Blackjack;
using OECS;
using OECS.PlayTest;
using Xunit;
using Xunit.Abstractions;

namespace Game.Blackjack.Tests;

/// <summary>
/// Baseline snapshot and log tests for Blackjack.
/// Captures the world state as text and R3 change logs so they can be
/// reviewed manually and compared across changes.
/// </summary>
public class SnapshotTests
{
    private readonly ITestOutputHelper _output;

    public SnapshotTests(ITestOutputHelper output)
    {
        _output = output;
    }

    [Fact]
    public void Snapshot_InitialState()
    {
        var (world, _) = TestHelpers.SetupGame();

        var snapshot = TestHelpers.SnapshotWorld(world);
        _output.WriteLine(snapshot);

        snapshot.Should().Contain("Phase: Betting");
        snapshot.Should().Contain("Chips: 100");
        snapshot.Should().Contain("Round: 1");
    }

    [Fact]
    public void Snapshot_AfterDeal()
    {
        var (world, group) = TestHelpers.SetupGame(seed: 42);

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        var snapshot = TestHelpers.SnapshotWorld(world);
        _output.WriteLine(snapshot);

        snapshot.Should().Contain("Phase: PlayerTurn");
        snapshot.Should().Contain("Chips: 90");
        snapshot.Should().Contain("Bet: 10");
        snapshot.Should().Contain("Player hand:");
        snapshot.Should().Contain("Dealer hand:");
        snapshot.Should().Contain("Cards in deck:");
    }

    [Fact]
    public void Snapshot_AfterHit()
    {
        var (world, group) = TestHelpers.SetupGame(seed: 42);

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        world.Commands.Enqueue(new HitCommand());
        group.RunLogical();

        var snapshot = TestHelpers.SnapshotWorld(world);
        _output.WriteLine(snapshot);

        snapshot.Should().NotContain("Phase: Dealing");
    }

    [Fact]
    public void Snapshot_AfterStand()
    {
        var (world, group) = TestHelpers.SetupGame(seed: 42);

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        world.Commands.Enqueue(new StandCommand());
        group.RunLogical();

        var snapshot = TestHelpers.SnapshotWorld(world);
        _output.WriteLine(snapshot);

        snapshot.Should().Contain("Phase: RoundOver");
        snapshot.Should().Contain("Result:");
    }

    [Fact]
    public void Log_ReactivityDuringRound()
    {
        var (world, group) = TestHelpers.SetupGame(seed: 42);

        using var capture = new ObservableCapture(world);
        capture.FormatWith<Card>(c => $"{c.Rank} of {c.Suit}");
        capture.FormatWith<GameState>(s => $"{s.Phase} Chips={s.Chips} Bet={s.CurrentBet} Round={s.RoundNumber}");

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        world.Commands.Enqueue(new StandCommand());
        group.RunLogical();

        var logText = string.Join("\n", capture.GetLogLines());
        _output.WriteLine(logText);

        capture.GetLogLines().Should().Contain(l => l.Contains("EntityAdded"));
        capture.GetLogLines().Should().Contain(l => l.Contains("ComponentAdded") && l.Contains("Card"));
        capture.GetLogLines().Should().Contain(l => l.Contains("ComponentModified") && l.Contains("GameState"));
    }

    [Fact]
    public void Serialization_RoundTrip_PreservesCoreState()
    {
        var (world, group) = TestHelpers.SetupGame(seed: 42);

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        var before = TestHelpers.SnapshotWorld(world);

        using var stream = new MemoryStream();
        WorldSerializer.Save(world, stream);
        stream.Position = 0;

        var world2 = new World();
        WorldSerializer.Load(world2, stream);

        var after = TestHelpers.SnapshotWorld(world2);

        _output.WriteLine("=== Before ===");
        _output.WriteLine(before);
        _output.WriteLine("=== After ===");
        _output.WriteLine(after);

        var state = world2.ReadSingleton<GameState>();
        state.Phase.Should().Be(GamePhase.PlayerTurn);
        state.Chips.Should().Be(90);
        state.CurrentBet.Should().Be(10);
        state.RoundNumber.Should().Be(1);

        after.Should().Contain("Card entities: 52");
    }
}