PkmnLib.NET/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/FocusEnergyTests.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="FocusEnergy"/> script, which implements Focus Energy.
/// Behavior is verified against the Bulbapedia page for Focus Energy (Generation VII behavior: the
/// Generation II base effect with the Generation III change applied).
/// The lasting part of the effect (the raised critical hit ratio) is implemented by the
/// <see cref="FocusEnergyEffect"/> volatile script, which the move script is responsible for attaching
/// to the user.
/// </summary>
public class FocusEnergyTests
{
    /// <summary>
    /// Creates a fully mocked test setup for Focus Energy tests.
    /// </summary>
    private static (FocusEnergy focusEnergy, IExecutingMove move, IBattlePokemon target, IScriptSet volatileSet,
        IHitData hitData) CreateTestSetup()
    {
        var focusEnergy = new FocusEnergy();
        var move = Substitute.For<IExecutingMove>();
        var target = Substitute.For<IBattlePokemon>();
        var hitData = Substitute.For<IHitData>();
        move.GetHitData(target, 0).Returns(hitData);

        var volatileSet = Substitute.For<IScriptSet>();
        target.Volatile.Returns(volatileSet);

        return (focusEnergy, move, target, volatileSet, hitData);
    }

    /// <summary>
    /// Helper to extract the script passed to the volatile set's Add call.
    /// </summary>
    private static Script? GetAddedScript(IScriptSet volatileSet)
    {
        var call = volatileSet.ReceivedCalls().FirstOrDefault(c => c.GetMethodInfo().Name == "Add");
        return call?.GetArguments()[0] as Script;
    }

    /// <summary>
    /// Bulbapedia (Generation II): "Focus Energy now permanently increases the user's critical hit ratio."
    /// The lasting effect is implemented by attaching a <see cref="FocusEnergyEffect"/> volatile script to the
    /// target of the move (Focus Energy is self-targeted, so the target is the user).
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_Called_AddsFocusEnergyEffectToTargetVolatile()
    {
        // Arrange
        var (focusEnergy, move, target, volatileSet, _) = CreateTestSetup();

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

        // Assert
        await Assert.That(GetAddedScript(volatileSet) is FocusEnergyEffect).IsTrue();
    }

    /// <summary>
    /// Bulbapedia (Generations III to V, unchanged through Generation VII): "Focus Energy now increases the
    /// user's critical hit ratio by two stages instead of one."
    /// The volatile effect applied by <see cref="FocusEnergy"/> must therefore raise the critical hit stage
    /// by two when the affected Pokémon attacks.
    /// </summary>
    [Test, Arguments((byte)0, (byte)2), Arguments((byte)1, (byte)3), Arguments((byte)2, (byte)4)]
    public async Task OnSecondaryEffect_AppliedEffect_RaisesCriticalHitStageByTwoStages(byte initialStage,
        byte expectedStage)
    {
        // Arrange
        var (focusEnergy, move, target, volatileSet, _) = CreateTestSetup();
        focusEnergy.OnSecondaryEffect(move, target, 0);
        var addedScript = GetAddedScript(volatileSet);
        await Assert.That(addedScript is IScriptChangeCriticalStage).IsTrue();

        // Act - run the applied effect's critical stage hook, as would happen when the user attacks
        var stage = initialStage;
        ((IScriptChangeCriticalStage)addedScript!).ChangeCriticalStage(move, target, 0, ref stage);

        // Assert
        await Assert.That(stage).IsEqualTo(expectedStage);
    }

    /// <summary>
    /// Bulbapedia: "The effect of Focus Energy cannot stack, and it will fail if the user is already under its
    /// effect." (Stated for Generation I and never reverted by a later generational change, so still the
    /// behavior in Generation VII.)
    /// When the user already has the <see cref="FocusEnergyEffect"/> volatile script, the hit must fail.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_UserAlreadyUnderEffect_HitFails()
    {
        // Arrange
        var (focusEnergy, move, target, volatileSet, hitData) = CreateTestSetup();
        volatileSet.Contains<FocusEnergyEffect>().Returns(true);

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

        // Assert
        await Assert.That(hitData.ReceivedCalls().Any(c => c.GetMethodInfo().Name == "Fail")).IsTrue();
    }

    /// <summary>
    /// Bulbapedia: "The effect of Focus Energy cannot stack". A second use on a user that is already under the
    /// effect must not attach a second <see cref="FocusEnergyEffect"/> volatile script, which would otherwise
    /// stack another two critical hit stages on top of the existing ones.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_UserAlreadyUnderEffect_DoesNotAddEffectAgain()
    {
        // Arrange
        var (focusEnergy, move, target, volatileSet, _) = CreateTestSetup();
        volatileSet.Contains<FocusEnergyEffect>().Returns(true);

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

        // Assert
        await Assert.That(GetAddedScript(volatileSet)).IsNull();
    }
}