minesweeper-codex/tests/Minesweeper.Tests/SolverTests.cs

using Minesweeper.Game;
using Xunit;

namespace Minesweeper.Tests;

public class SolverTests
{
    [Fact]
    public void AnEmptyMinefieldIsClearedInOneGo()
    {
        var game = new MinesweeperGame(new Board(5, 5, 0), new Random(1));
        var result = new Solver(game, new Random(2)).Run();

        Assert.Equal(GameStatus.Won, result.Status);
        Assert.Equal(25, game.RevealedCount);
        Assert.Equal(0, result.Guesses);
    }

    [Fact]
    public void TheStepBudgetStopsTheSearch()
    {
        var game = new MinesweeperGame(new Board(16, 16, 40), new Random(3));
        var result = new Solver(game, new Random(4), maxSteps: 1).Run();

        Assert.Equal(1, result.Steps);
        Assert.Equal(GameStatus.Playing, game.Status);
    }

    [Fact]
    public void TheSameSeedPlaysTheSameGame()
    {
        var first = Play(21, out var firstGame);
        var second = Play(21, out var secondGame);

        Assert.Equal(first.Status, second.Status);
        Assert.Equal(firstGame.RevealedCount, secondGame.RevealedCount);
        Assert.Equal(first.Guesses, second.Guesses);
    }

    [Fact]
    public void DeductionsClearMostBeginnerBoards()
    {
        var wins = 0;
        for (var seed = 1; seed <= 10; seed++)
        {
            if (Play(seed, out _).Status == GameStatus.Won)
                wins++;
        }

        Assert.True(wins >= 8, $"expected the solver to win at least 8 of 10 beginner boards, won {wins}");
    }

    [Fact]
    public void SolverNeverLeavesAHiddenSafeSquareBehind()
    {
        for (var seed = 1; seed <= 5; seed++)
        {
            Play(seed, out var game);
            if (game.Status != GameStatus.Won)
                continue;

            Assert.Equal(game.TotalSafeCells, game.RevealedCount);
        }
    }

    private static SolverResult Play(int seed, out MinesweeperGame game)
    {
        var random = new Random(seed);
        game = new MinesweeperGame(new Board(9, 9, 10), random) { ReserveSafeZone = true };
        return new Solver(game, random).Run();
    }
}