PkmnLib.NET/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/LastResortTests.cs

using PkmnLib.Dynamic.Models;
using PkmnLib.Dynamic.Models.Choices;
using PkmnLib.Plugin.Gen7.Scripts.Moves;
using PkmnLib.Static.Moves;
using PkmnLib.Static.Utils;

namespace PkmnLib.Plugin.Gen7.Tests.Scripts.Moves;

/// <summary>
/// Tests for the <see cref="LastResort"/> move script.
/// Gen VII Bulbapedia behavior: "Last Resort will fail unless the Pokémon has used all of its other moves
/// at least once while on the field. Using a move before switching out and back in does not count towards
/// being able to use Last Resort. Last Resort will fail if it is the only move the user knows".
/// </summary>
public class LastResortTests
{
    /// <summary>
    /// Creates a mocked <see cref="ILearnedMove"/> with the given move name.
    /// </summary>
    private static ILearnedMove CreateLearnedMove(string name)
    {
        var moveData = Substitute.For<IMoveData>();
        moveData.Name.Returns(new StringKey(name));
        moveData.SecondaryEffect.Returns((ISecondaryEffect?)null);
        var learnedMove = Substitute.For<ILearnedMove>();
        learnedMove.MoveData.Returns(moveData);
        return learnedMove;
    }

    /// <summary>
    /// Creates a mocked user in battle that knows the given moves.
    /// </summary>
    private static IBattlePokemon CreateUser(params ILearnedMove?[] moves)
    {
        var user = Substitute.For<IBattlePokemon>();
        user.Moves.Returns(moves);
        var battle = Substitute.For<IBattle>();
        user.Battle.Returns(battle);
        return user;
    }

    /// <summary>
    /// Sets the battle's previous turn choices, one inner array per turn (oldest first).
    /// </summary>
    private static void SetPreviousTurns(IBattlePokemon user, params ITurnChoice[][] turns)
    {
        user.Battle.PreviousTurnChoices.Returns(turns.Select(IReadOnlyList<ITurnChoice> (t) => t).ToList());
    }

    /// <summary>
    /// Runs <see cref="LastResort.PreventMoveSelection"/> for the user selecting the given Last Resort
    /// move and returns whether the selection was prevented.
    /// </summary>
    private static bool RunPreventMoveSelection(IBattlePokemon user, ILearnedMove lastResort)
    {
        var script = new LastResort();
        var choice = new MoveChoice(user, lastResort, 0, 0);
        var prevent = false;
        script.PreventMoveSelection(choice, ref prevent);
        return prevent;
    }

    /// <summary>
    /// Bulbapedia: "Last Resort will fail unless the Pokémon has used all of its other moves at least once
    /// while on the field." — with every other move used, selecting Last Resort is allowed.
    /// </summary>
    [Test]
    public async Task PreventMoveSelection_AllOtherMovesUsedOnField_SelectionAllowed()
    {
        // Arrange
        var tackle = CreateLearnedMove("tackle");
        var growl = CreateLearnedMove("growl");
        var lastResort = CreateLearnedMove("last_resort");
        var user = CreateUser(tackle, growl, lastResort);
        SetPreviousTurns(user, [new MoveChoice(user, tackle, 0, 0)], [new MoveChoice(user, growl, 0, 0)]);

        // Act
        var prevent = RunPreventMoveSelection(user, lastResort);

        // Assert
        await Assert.That(prevent).IsFalse();
    }

    /// <summary>
    /// Bulbapedia: "Last Resort will fail unless the Pokémon has used all of its other moves at least once
    /// while on the field." — with one of the other moves never used, the selection is prevented.
    /// </summary>
    [Test]
    public async Task PreventMoveSelection_NotAllOtherMovesUsed_SelectionPrevented()
    {
        // Arrange
        var tackle = CreateLearnedMove("tackle");
        var growl = CreateLearnedMove("growl");
        var lastResort = CreateLearnedMove("last_resort");
        var user = CreateUser(tackle, growl, lastResort);
        SetPreviousTurns(user, [new MoveChoice(user, tackle, 0, 0)]);

        // Act
        var prevent = RunPreventMoveSelection(user, lastResort);

        // Assert
        await Assert.That(prevent).IsTrue();
    }

    /// <summary>
    /// Bulbapedia: Last Resort fails "unless the Pokémon has used all of its other moves at least once" —
    /// with no moves used at all (e.g. the first turn), the selection is prevented.
    /// </summary>
    [Test]
    public async Task PreventMoveSelection_NoMovesUsedYet_SelectionPrevented()
    {
        // Arrange
        var tackle = CreateLearnedMove("tackle");
        var lastResort = CreateLearnedMove("last_resort");
        var user = CreateUser(tackle, lastResort);
        SetPreviousTurns(user);

        // Act
        var prevent = RunPreventMoveSelection(user, lastResort);

        // Assert
        await Assert.That(prevent).IsTrue();
    }

    /// <summary>
    /// Bulbapedia: "Last Resort will fail if it is the only move the user knows".
    /// </summary>
    [Test]
    public async Task PreventMoveSelection_LastResortOnlyKnownMove_SelectionPrevented()
    {
        // Arrange
        var lastResort = CreateLearnedMove("last_resort");
        var user = CreateUser(lastResort, null, null, null);
        SetPreviousTurns(user);

        // Act
        var prevent = RunPreventMoveSelection(user, lastResort);

        // Assert
        await Assert.That(prevent).IsTrue();
    }

    /// <summary>
    /// Bulbapedia: "Using a move before switching out and back in does not count towards being able to use
    /// Last Resort." — a move used only before the user was switched back in does not enable Last Resort.
    /// </summary>
    [Test]
    public async Task PreventMoveSelection_MoveOnlyUsedBeforeSwitchingOut_SelectionPrevented()
    {
        // Arrange
        var tackle = CreateLearnedMove("tackle");
        var lastResort = CreateLearnedMove("last_resort");
        var user = CreateUser(tackle, lastResort);
        var ally = Substitute.For<IBattlePokemon>();
        SetPreviousTurns(user, [new MoveChoice(user, tackle, 0, 0)], [new SwitchChoice(user, ally)],
            [new SwitchChoice(ally, user)]);
        // The user re-entered the field during turn 3, after all three recorded turns' choices were made.
        user.SwitchInTurn.Returns(3u);

        // Act
        var prevent = RunPreventMoveSelection(user, lastResort);

        // Assert
        await Assert.That(prevent).IsTrue();
    }

    /// <summary>
    /// Bulbapedia: "A move will still count as used for Last Resort even if it would have no effect, so for
    /// example, using Snore when the user is awake or a move missing due to accuracy or evasion." — a failed
    /// move choice still counts as used.
    /// </summary>
    [Test]
    public async Task PreventMoveSelection_OtherMoveFailed_SelectionAllowed()
    {
        // Arrange
        var tackle = CreateLearnedMove("tackle");
        var lastResort = CreateLearnedMove("last_resort");
        var user = CreateUser(tackle, lastResort);
        var failedTackle = new MoveChoice(user, tackle, 0, 0);
        failedTackle.Fail();
        SetPreviousTurns(user, [failedTackle]);

        // Act
        var prevent = RunPreventMoveSelection(user, lastResort);

        // Assert
        await Assert.That(prevent).IsFalse();
    }

    /// <summary>
    /// Bulbapedia: the requirement is that "the Pokémon has used all of its other moves" — a move used by a
    /// different Pokémon does not count for the user.
    /// </summary>
    [Test]
    public async Task PreventMoveSelection_MoveUsedByAnotherPokemon_SelectionPrevented()
    {
        // Arrange
        var tackle = CreateLearnedMove("tackle");
        var lastResort = CreateLearnedMove("last_resort");
        var user = CreateUser(tackle, lastResort);
        var other = Substitute.For<IBattlePokemon>();
        SetPreviousTurns(user, [new MoveChoice(other, tackle, 0, 0)]);

        // Act
        var prevent = RunPreventMoveSelection(user, lastResort);

        // Assert
        await Assert.That(prevent).IsTrue();
    }
}