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

using PkmnLib.Dynamic.Models;
using PkmnLib.Dynamic.ScriptHandling;
using PkmnLib.Plugin.Gen7.Scripts.Moves;
using PkmnLib.Plugin.Gen7.Scripts.Pokemon;

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

/// <summary>
/// Tests for the <see cref="HelpingHand"/> move script and the <see cref="HelpingHandEffect"/> volatile script it
/// applies to the ally.
/// Gen VII Bulbapedia behavior: "Helping Hand is an increased priority move that will increase the damage done by
/// the user's ally this turn by 50%. It will fail if there is no adjacent ally, or if the ally has already acted
/// this turn." and "If Helping Hand is used multiple times in a turn, all targeting the same Pokémon, the boosts
/// are cumulative."
/// </summary>
public class HelpingHandTests
{
    /// <summary>
    /// Creates an ally with a real <see cref="ScriptSet"/> as its <see cref="IBattlePokemon.Volatile"/> set, so that
    /// adding, stacking, and removing the <see cref="HelpingHandEffect"/> behaves as it would in battle.
    /// </summary>
    private static (IBattlePokemon ally, ScriptSet volatiles) CreateAllyWithRealVolatileSet()
    {
        var ally = Substitute.For<IBattlePokemon>();
        var volatiles = new ScriptSet(ally);
        // ScriptSet.Add runs the IScriptPreventVolatileAdd hook over the owner's scripts; give the mock a real
        // iterator so that hook pass runs (empty of blockers here).
        ally.GetScripts().Returns(_ => new ScriptIterator(new IEnumerable<ScriptContainer>[] { volatiles }));
        ally.Volatile.Returns(volatiles);
        return (ally, volatiles);
    }

    /// <summary>
    /// Applies <see cref="IScriptChangeBasePower.ChangeBasePower"/> of every script in the ally's volatile set to
    /// the given base power, as the battle engine would when the ally uses its move.
    /// </summary>
    private static ushort RunChangeBasePowerHooks(ScriptSet volatiles, ushort basePower)
    {
        var allyMove = Substitute.For<IExecutingMove>();
        var opponent = Substitute.For<IBattlePokemon>();
        foreach (var container in volatiles)
        {
            if (container.Script is IScriptChangeBasePower changeBasePower)
                changeBasePower.ChangeBasePower(allyMove, opponent, 0, ref basePower);
        }

        return basePower;
    }

    /// <summary>
    /// Bulbapedia: "Helping Hand is an increased priority move that will increase the damage done by the user's
    /// ally this turn by 50%." Using the move attaches the <see cref="HelpingHandEffect"/> volatile to the targeted
    /// ally.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_UsedOnAlly_AddsHelpingHandEffectToAlly()
    {
        // Arrange
        var helpingHand = new HelpingHand();
        var move = Substitute.For<IExecutingMove>();
        var ally = Substitute.For<IBattlePokemon>();

        // Act
        helpingHand.OnSecondaryEffect(move, ally, 0);

        // Assert
        var addCall = ally.Volatile.ReceivedCalls().FirstOrDefault(c => c.GetMethodInfo().Name == "Add");
        await Assert.That(addCall).IsNotNull();
        await Assert.That(addCall!.GetArguments()[0] is HelpingHandEffect).IsTrue();
    }

    /// <summary>
    /// Bulbapedia: Helping Hand "will increase the damage done by the user's ally this turn by 50%."
    /// The <see cref="HelpingHandEffect"/> multiplies the boosted move's base power by 1.5, truncating fractions.
    /// </summary>
    [Test, Arguments((ushort)100, (ushort)150), Arguments((ushort)60, (ushort)90), Arguments((ushort)65, (ushort)97),
     Arguments((ushort)1, (ushort)1)]
    public async Task ChangeBasePower_EffectActive_BasePowerIncreasedByFiftyPercent(ushort basePower,
        ushort expectedPower)
    {
        // Arrange
        var effect = new HelpingHandEffect();
        var move = Substitute.For<IExecutingMove>();
        var target = Substitute.For<IBattlePokemon>();

        // Act
        effect.ChangeBasePower(move, target, 0, ref basePower);

        // Assert
        await Assert.That(basePower).IsEqualTo(expectedPower);
    }

    /// <summary>
    /// Technical test: boosting a very large base power clamps at <see cref="ushort.MaxValue"/> instead of
    /// overflowing.
    /// </summary>
    [Test]
    public async Task ChangeBasePower_LargeBasePower_ClampsAtMaxValue()
    {
        // Arrange
        var effect = new HelpingHandEffect();
        var move = Substitute.For<IExecutingMove>();
        var target = Substitute.For<IBattlePokemon>();
        var basePower = ushort.MaxValue;

        // Act
        effect.ChangeBasePower(move, target, 0, ref basePower);

        // Assert
        await Assert.That(basePower).IsEqualTo(ushort.MaxValue);
    }

    /// <summary>
    /// Bulbapedia: "If Helping Hand is used multiple times in a turn, all targeting the same Pokémon, the boosts
    /// are cumulative. The move power will increase by 125% if there are two Helping Hands".
    /// Two Helping Hands on the same ally should therefore boost 100 base power to 225 (1.5 × 1.5).
    /// </summary>
    [Test]
    public async Task ChangeBasePower_TwoHelpingHandsOnSameAlly_BoostsAreCumulative()
    {
        // Arrange
        var helpingHand = new HelpingHand();
        var move = Substitute.For<IExecutingMove>();
        var (ally, volatiles) = CreateAllyWithRealVolatileSet();

        // Act - two different Pokémon use Helping Hand on the same ally in the same turn
        helpingHand.OnSecondaryEffect(move, ally, 0);
        helpingHand.OnSecondaryEffect(move, ally, 0);
        var boosted = RunChangeBasePowerHooks(volatiles, 100);

        // Assert - 100 × 1.5 × 1.5 = 225
        await Assert.That(boosted).IsEqualTo((ushort)225);
    }

    /// <summary>
    /// Bulbapedia: "The move power will increase by ... 237.5% if there are three [Helping Hands]."
    /// Three Helping Hands on the same ally should boost 100 base power to 337 (1.5³ = 3.375, truncated).
    /// </summary>
    [Test]
    public async Task ChangeBasePower_ThreeHelpingHandsOnSameAlly_BoostsAreCumulative()
    {
        // Arrange
        var helpingHand = new HelpingHand();
        var move = Substitute.For<IExecutingMove>();
        var (ally, volatiles) = CreateAllyWithRealVolatileSet();

        // Act
        helpingHand.OnSecondaryEffect(move, ally, 0);
        helpingHand.OnSecondaryEffect(move, ally, 0);
        helpingHand.OnSecondaryEffect(move, ally, 0);
        var boosted = RunChangeBasePowerHooks(volatiles, 100);

        // Assert - 100 × 1.5 × 1.5 × 1.5 = 337.5, truncated to 337
        await Assert.That(boosted).IsEqualTo((ushort)337);
    }

    /// <summary>
    /// Bulbapedia: Helping Hand increases "the damage done by the user's ally this turn" — the boost only lasts
    /// for the turn it was used, so the <see cref="HelpingHandEffect"/> removes itself at the end of the turn.
    /// </summary>
    [Test]
    public async Task OnEndTurn_TurnEnds_EffectRemovesItselfFromAlly()
    {
        // Arrange
        var (ally, volatiles) = CreateAllyWithRealVolatileSet();
        var helpingHand = new HelpingHand();
        var move = Substitute.For<IExecutingMove>();
        helpingHand.OnSecondaryEffect(move, ally, 0);
        await Assert.That(volatiles.TryGet<HelpingHandEffect>(out var effect)).IsTrue();

        // Act
        effect!.OnEndTurn(ally, Substitute.For<IBattle>());

        // Assert
        await Assert.That(volatiles.TryGet<HelpingHandEffect>(out _)).IsFalse();
    }

    /// <summary>
    /// Bulbapedia: the 50% boost applies "this turn" — after the effect has been removed at the end of the turn,
    /// the ally's moves are no longer boosted.
    /// </summary>
    [Test]
    public async Task ChangeBasePower_AfterEndOfTurn_BasePowerNoLongerBoosted()
    {
        // Arrange
        var (ally, volatiles) = CreateAllyWithRealVolatileSet();
        var helpingHand = new HelpingHand();
        var move = Substitute.For<IExecutingMove>();
        helpingHand.OnSecondaryEffect(move, ally, 0);
        volatiles.TryGet<HelpingHandEffect>(out var effect);

        // Act
        effect!.OnEndTurn(ally, Substitute.For<IBattle>());
        var boosted = RunChangeBasePowerHooks(volatiles, 100);

        // Assert
        await Assert.That(boosted).IsEqualTo((ushort)100);
    }
}