PkmnLib.NET/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/FlailTests.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="Flail"/> move script.
/// Gen VII Bulbapedia behavior: "Flail inflicts damage and has no additional effect. Its power is based on
/// the user's current HP as a percentage of its maximum HP, which is higher the lower the user's HP is."
/// The power tiers (all generations except IV) are: 20 power at HP ≥ 68.8%, 40 at 35.4% ≤ HP &lt; 68.8%,
/// 80 at 20.8% ≤ HP &lt; 35.4%, 100 at 10.4% ≤ HP &lt; 20.8%, 150 at 4.2% ≤ HP &lt; 10.4%, and
/// 200 at HP &lt; 4.2%. These percentages correspond to the tiers of floor(48 × current HP / max HP).
/// </summary>
public class FlailTests
{
    /// <summary>
    /// Creates a fully mocked test setup for Flail tests with the user at the given current and maximum HP.
    /// </summary>
    private static (Flail script, IExecutingMove move, IBattlePokemon target) CreateTestSetup(uint currentHp,
        uint maxHp)
    {
        var script = new Flail();
        var move = Substitute.For<IExecutingMove>();
        var target = Substitute.For<IBattlePokemon>();
        var user = Substitute.For<IBattlePokemon>();
        user.CurrentHealth.Returns(currentHp);
        user.BoostedStats.Returns(new StatisticSet<uint>(maxHp, 0, 0, 0, 0, 0));
        move.User.Returns(user);
        return (script, move, target);
    }

    /// <summary>
    /// Bulbapedia: Flail's power is 20 when the user's HP is at least 68.8% of its maximum.
    /// A user at full health uses the weakest power tier.
    /// </summary>
    [Test]
    public async Task ChangeBasePower_UserAtFullHealth_PowerIs20()
    {
        // Arrange
        var (script, move, target) = CreateTestSetup(100, 100);
        ushort basePower = 20;

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

        // Assert
        await Assert.That(basePower).IsEqualTo((ushort)20);
    }

    /// <summary>
    /// Bulbapedia: Flail's power is 200 when the user's HP is below 4.2% of its maximum.
    /// A user at 1 HP uses the strongest power tier.
    /// </summary>
    [Test]
    public async Task ChangeBasePower_UserAtOneHp_PowerIs200()
    {
        // Arrange
        var (script, move, target) = CreateTestSetup(1, 100);
        ushort basePower = 20;

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

        // Assert
        await Assert.That(basePower).IsEqualTo((ushort)200);
    }

    /// <summary>
    /// Bulbapedia: "Its power is based on the user's current HP as a percentage of its maximum HP, which is
    /// higher the lower the user's HP is". These rows cover the extremes of the table: full health
    /// (HP ≥ 68.8% → 20 power) and nearly fainted (HP &lt; 4.2% → 200 power).
    /// </summary>
    [Test, Arguments(100u, 100u, 20), Arguments(4u, 100u, 200), Arguments(1u, 100u, 200)]
    // 48/48 -> 20
    // floor(1.92) = 1 -> 200
    // floor(0.48) = 0 -> 200
    public async Task ChangeBasePower_HpAtExtremes_MatchesFlailPowerTable(uint currentHp, uint maxHp, int expectedPower)
    {
        // Arrange
        var (script, move, target) = CreateTestSetup(currentHp, maxHp);
        ushort basePower = 20;

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

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

    /// <summary>
    /// Bulbapedia: "Its power is based on the user's current HP as a percentage of its maximum HP, which is
    /// higher the lower the user's HP is", following the tiers 20 (HP ≥ 68.8%), 40 (35.4% ≤ HP &lt; 68.8%),
    /// 80 (20.8% ≤ HP &lt; 35.4%), 100 (10.4% ≤ HP &lt; 20.8%), 150 (4.2% ≤ HP &lt; 10.4%) and 200 (HP &lt; 4.2%).
    /// The rows cover both boundary values of every tier, verifying the integer arithmetic of
    /// floor(48 × current HP / max HP).
    /// </summary>
    [Test, Arguments(69u, 100u, 20), Arguments(68u, 100u, 40), Arguments(36u, 100u, 40), Arguments(35u, 100u, 80),
     Arguments(21u, 100u, 80), Arguments(20u, 100u, 100), Arguments(11u, 100u, 100), Arguments(10u, 100u, 150),
     Arguments(5u, 100u, 150), Arguments(150u, 300u, 40), Arguments(24u, 48u, 40), Arguments(7u, 48u, 100)]
    public async Task ChangeBasePower_HpFractionOfMax_MatchesFlailPowerTable(uint currentHp, uint maxHp,
        int expectedPower)
    {
        // Arrange
        var (script, move, target) = CreateTestSetup(currentHp, maxHp);
        ushort basePower = 20;

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

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