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

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

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

/// <summary>
/// Tests for the <see cref="GuardSwap"/> move script.
/// Gen VII Bulbapedia behavior: "Guard Swap switches the user's Defense stat stages and Special Defense
/// stat stages with the target's Defense stat stages and Special Defense stat stages."
/// </summary>
public class GuardSwapTests
{
    private static (GuardSwap script, IExecutingMove move, IPokemon user, IPokemon target) CreateTestSetup(
        sbyte userDefense, sbyte userSpecialDefense, sbyte targetDefense, sbyte targetSpecialDefense)
    {
        var script = new GuardSwap();
        var move = Substitute.For<IExecutingMove>();

        var user = Substitute.For<IPokemon>();
        user.StatBoost.Returns(new StatBoostStatisticSet(0, 0, userDefense, 0, userSpecialDefense, 0));
        move.User.Returns(user);

        var target = Substitute.For<IPokemon>();
        target.StatBoost.Returns(new StatBoostStatisticSet(0, 0, targetDefense, 0, targetSpecialDefense, 0));

        return (script, move, user, target);
    }

    /// <summary>
    /// Helper to extract the arguments of the received ChangeStatBoost call for the given statistic, or
    /// null when that stat was not changed. Received-call inspection is used instead of NSubstitute
    /// argument matchers because the trailing EventBatchId parameter cannot be bound by <c>Arg.Any</c>.
    /// </summary>
    private static object?[]? GetStatBoostArgs(IPokemon pokemon, Statistic stat) =>
        pokemon.ReceivedCalls().Where(c => c.GetMethodInfo().Name == "ChangeStatBoost").Select(c => c.GetArguments())
            .FirstOrDefault(args => (Statistic)args[0]! == stat);

    /// <summary>
    /// Bulbapedia: "Guard Swap switches the user's Defense stat stages ... with the target's Defense stat
    /// stages." The user at +2 Defense and the target at -1 Defense must end up at -1 and +2
    /// respectively, so the user is changed by -3 and the target by +3.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_DifferentDefenseStages_StagesAreSwapped()
    {
        // Arrange
        var (script, move, user, target) = CreateTestSetup(2, 0, -1, 0);

        // Act
        script.OnSecondaryEffect(move, target, 0);

        // Assert
        var userArgs = GetStatBoostArgs(user, Statistic.Defense);
        var targetArgs = GetStatBoostArgs(target, Statistic.Defense);
        await Assert.That(userArgs).IsNotNull();
        await Assert.That((sbyte)userArgs![1]!).IsEqualTo((sbyte)-3);
        await Assert.That(targetArgs).IsNotNull();
        await Assert.That((sbyte)targetArgs![1]!).IsEqualTo((sbyte)3);
    }

    /// <summary>
    /// Bulbapedia: the swap also covers the "Special Defense stat stages". The user at -2 Special Defense
    /// and the target at +3 must end up at +3 and -2 respectively, so the user is changed by +5 and the
    /// target by -5.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_DifferentSpecialDefenseStages_StagesAreSwapped()
    {
        // Arrange
        var (script, move, user, target) = CreateTestSetup(0, -2, 0, 3);

        // Act
        script.OnSecondaryEffect(move, target, 0);

        // Assert
        var userArgs = GetStatBoostArgs(user, Statistic.SpecialDefense);
        var targetArgs = GetStatBoostArgs(target, Statistic.SpecialDefense);
        await Assert.That(userArgs).IsNotNull();
        await Assert.That((sbyte)userArgs![1]!).IsEqualTo((sbyte)5);
        await Assert.That(targetArgs).IsNotNull();
        await Assert.That((sbyte)targetArgs![1]!).IsEqualTo((sbyte)-5);
    }

    /// <summary>
    /// Bulbapedia: the swap is unconditional — the change is applied with force so clamping or
    /// prevention effects cannot block the exchange of stages.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_Always_ChangesAreForced()
    {
        // Arrange
        var (script, move, user, target) = CreateTestSetup(2, 0, -1, 0);

        // Act
        script.OnSecondaryEffect(move, target, 0);

        // Assert
        var userArgs = GetStatBoostArgs(user, Statistic.Defense);
        var targetArgs = GetStatBoostArgs(target, Statistic.Defense);
        await Assert.That((bool)userArgs![3]!).IsTrue(); // forced
        await Assert.That((bool)targetArgs![3]!).IsTrue(); // forced
        await Assert.That((bool)userArgs[2]!).IsTrue(); // self-inflicted for the user
        await Assert.That((bool)targetArgs[2]!).IsFalse(); // not self-inflicted for the target
    }

    /// <summary>
    /// Bulbapedia: only the "Defense stat stages and Special Defense stat stages" are switched — the
    /// other stat stages are left untouched.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_Always_OtherStagesUnchanged()
    {
        // Arrange
        var (script, move, user, target) = CreateTestSetup(2, -2, -1, 3);

        // Act
        script.OnSecondaryEffect(move, target, 0);

        // Assert
        await Assert.That(GetStatBoostArgs(user, Statistic.Attack)).IsNull();
        await Assert.That(GetStatBoostArgs(user, Statistic.SpecialAttack)).IsNull();
        await Assert.That(GetStatBoostArgs(user, Statistic.Speed)).IsNull();
        await Assert.That(GetStatBoostArgs(target, Statistic.Attack)).IsNull();
    }

    /// <summary>
    /// When both Pokémon have equal stages, swapping is a net-zero change for both sides.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_EqualStages_ChangeIsZero()
    {
        // Arrange
        var (script, move, user, target) = CreateTestSetup(1, 2, 1, 2);

        // Act
        script.OnSecondaryEffect(move, target, 0);

        // Assert
        var userDefenseArgs = GetStatBoostArgs(user, Statistic.Defense);
        var userSpecialDefenseArgs = GetStatBoostArgs(user, Statistic.SpecialDefense);
        await Assert.That((sbyte)userDefenseArgs![1]!).IsEqualTo((sbyte)0);
        await Assert.That((sbyte)userSpecialDefenseArgs![1]!).IsEqualTo((sbyte)0);
    }
}