Chessistics/chessistics-tests/Rules/CollisionDetectorTests.cs

using Chessistics.Engine.Model;
using Chessistics.Engine.Rules;
using Xunit;

namespace Chessistics.Tests.Rules;

public class CollisionDetectorTests
{
    [Fact]
    public void NoCollision_PiecesOnDifferentCells()
    {
        var pieces = new List<PieceState>
        {
            new(1, PieceKind.Rook, new Coords(0, 0), new Coords(1, 0), 0) { CurrentCell = new Coords(0, 0) },
            new(2, PieceKind.Rook, new Coords(2, 0), new Coords(3, 0), 1) { CurrentCell = new Coords(2, 0) }
        };

        var collisions = CollisionDetector.DetectCollisions(pieces);
        Assert.Empty(collisions);
    }

    [Fact]
    public void Collision_TwoPiecesSameCell()
    {
        var cell = new Coords(1, 0);
        var pieces = new List<PieceState>
        {
            new(1, PieceKind.Rook, new Coords(0, 0), cell, 0) { CurrentCell = cell },
            new(2, PieceKind.Rook, new Coords(2, 0), cell, 1) { CurrentCell = cell }
        };

        var collisions = CollisionDetector.DetectCollisions(pieces);
        Assert.Single(collisions);
        Assert.Equal((1, 2, cell), collisions[0]);
    }

    [Fact]
    public void Collision_ThreePiecesSameCell()
    {
        var cell = new Coords(1, 0);
        var pieces = new List<PieceState>
        {
            new(1, PieceKind.Rook, new Coords(0, 0), cell, 0) { CurrentCell = cell },
            new(2, PieceKind.Rook, new Coords(2, 0), cell, 1) { CurrentCell = cell },
            new(3, PieceKind.Rook, new Coords(3, 0), cell, 2) { CurrentCell = cell }
        };

        var collisions = CollisionDetector.DetectCollisions(pieces);
        // 3 pairs: (1,2), (1,3), (2,3)
        Assert.Equal(3, collisions.Count);
    }
}