card_game/tests/Game.Core.Tests/AiSearchTests.cs

using CardGame.Core;
using Xunit;

namespace Game.Core.Tests;

public sealed class AiSearchTests
{
    [Fact]
    public void Prefers_face_damage_when_lethal_or_high_value()
    {
        var state = new GameState(9) { Catalog = Cards.Catalog };
        MatchSetup.PlaceSystemField(state, 0, Cards.BaseField);
        MatchSetup.PlaceSystemField(state, 1, Cards.BaseField);
        state.Players[1].Life = 1;
        var attacker = state.NewEntity(Cards.Wisp, 0, Zone.Board, Factions.Guard);
        attacker.EnteredOnTurn = 0;
        attacker.AttacksRemaining = 1;
        state.Board.Add(attacker);
        state.ActivePlayerIndex = 0;
        state.TurnNumber = 2;

        var legal = RulesEngine.GetLegalActions(state);
        var (action, top) = TurnBeamSearch.ChooseWithTrace(state, legal);
        Assert.IsType<AttackAction>(action);
        Assert.Contains(top, t => t.Chosen && t.Label.Contains("敌方主战者", StringComparison.Ordinal));
    }

    [Fact]
    public void PlayUntil_returns_step_trace()
    {
        var state = MatchSetup.CreateStartingBattle(11, Cards.Catalog, shuffle: false);
        state = RulesEngine.Execute(state, new EndTurnAction(0));
        var (_, trace) = TurnBeamSearch.PlayUntil(state, untilPlayerIndex: 0);
        Assert.NotEmpty(trace.Steps);
        Assert.All(trace.Steps, s => Assert.NotEmpty(s.TopCandidates));
    }

    [Fact]
    public void ChooseWithTrace_works_when_all_scores_are_negative()
    {
        var state = MatchSetup.CreateStartingBattle(13, Cards.Catalog, shuffle: false);
        state.Players[0].Life = 1;
        state.Players[1].Life = 20;
        var legal = RulesEngine.GetLegalActions(state);
        var (action, top) = TurnBeamSearch.ChooseWithTrace(state, legal);
        Assert.NotNull(action);
        Assert.Contains(top, t => t.Chosen);
    }
}