oecs-sharp/Game.TicTacToe.Tests/GameFlowTests.cs

using FluentAssertions;
using Game.TicTacToe;
using OECS;
using Xunit;

namespace Game.TicTacToe.Tests;

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

        var emptyCount = 0;
        foreach (var _ in world.Select(new Query<Cell>().Without<Mark>()))
            emptyCount++;

        emptyCount.Should().Be(9);
    }

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

        world.Commands.Enqueue(new PlaceMarkCommand { Row = 0, Col = 0 });
        group.RunLogical();

        var markedCount = 0;
        foreach (var it in world.Select<Cell, Mark>())
        {
            markedCount++;
            it.Val1.Row.Should().Be(0);
            it.Val1.Col.Should().Be(0);
            it.Val2.Player.Should().Be(Player.X);
        }

        markedCount.Should().Be(1);
    }

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

        world.Commands.Enqueue(new PlaceMarkCommand { Row = 0, Col = 0 }); // X
        group.RunLogical();
        world.ReadSingleton<GameState>().CurrentPlayer.Should().Be(Player.O);

        world.Commands.Enqueue(new PlaceMarkCommand { Row = 1, Col = 0 }); // O
        group.RunLogical();
        world.ReadSingleton<GameState>().CurrentPlayer.Should().Be(Player.X);
    }

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

        world.Commands.Enqueue(new PlaceMarkCommand { Row = 0, Col = 0 }); // X
        group.RunLogical();
        world.Commands.Enqueue(new PlaceMarkCommand { Row = 0, Col = 0 }); // O tries same cell
        group.RunLogical();

        var marks = new List<(int Row, int Col, Player Player)>();
        foreach (var it in world.Select<Cell, Mark>())
            marks.Add((it.Val1.Row, it.Val1.Col, it.Val2.Player));

        marks.Should().ContainSingle()
            .Which.Should().Be((0, 0, Player.X));
    }

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

        TestHelpers.PlayMoves(world, group, (0, 0), (1, 0), (0, 1), (1, 1), (0, 2));

        world.ReadSingleton<GameState>().Status.Should().Be(GameStatus.XWon);
    }

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

        TestHelpers.PlayMoves(world, group, (0, 0), (1, 0), (0, 1), (1, 1), (2, 2), (1, 2));

        world.ReadSingleton<GameState>().Status.Should().Be(GameStatus.OWon);
    }

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

        TestHelpers.PlayMoves(world, group, (0, 0), (1, 0), (1, 1), (1, 2), (2, 2));

        world.ReadSingleton<GameState>().Status.Should().Be(GameStatus.XWon);
    }

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

        TestHelpers.PlayMoves(world, group,
            (0, 0), (0, 1), (0, 2),
            (1, 1), (1, 0), (1, 2),
            (2, 1), (2, 0), (2, 2));

        world.ReadSingleton<GameState>().Status.Should().Be(GameStatus.Draw);
    }

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

        TestHelpers.PlayMoves(world, group, (0, 0), (1, 0), (0, 1), (1, 1), (0, 2));

        world.ReadSingleton<GameState>().Status.Should().Be(GameStatus.XWon);

        var moveCountBefore = world.ReadSingleton<GameState>().MoveCount;
        world.Commands.Enqueue(new PlaceMarkCommand { Row = 2, Col = 2 });
        group.RunLogical();

        world.ReadSingleton<GameState>().MoveCount.Should().Be(moveCountBefore);
    }

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

        TestHelpers.PlayMoves(world, group, (0, 0), (1, 0));

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

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

        var state = world2.ReadSingleton<GameState>();
        state.CurrentPlayer.Should().Be(Player.X);
        state.MoveCount.Should().Be(2);

        var marks = new List<(int Row, int Col, Player Player)>();
        foreach (var it in world2.Select<Cell, Mark>())
            marks.Add((it.Val1.Row, it.Val1.Col, it.Val2.Player));

        marks.Should().BeEquivalentTo([(0, 0, Player.X), (1, 0, Player.O)]);
    }
}