[Bug] Fix Fell Stinger giving boost when enemy dies to another source (#4723)

* check last source of damage instead of last successful attacker

* implement unit tests for Fell Stinger

---------

Co-authored-by: NightKev <34855794+DayKev@users.noreply.github.com>

src/phases/faint-phase.ts

@@ -119,7 +119,8 @@ export class FaintPhase extends PokemonPhase {
     const alivePlayField = globalScene.getField(true);
     alivePlayField.forEach(p => applyPostKnockOutAbAttrs(PostKnockOutAbAttr, p, pokemon));
     if (pokemon.turnData?.attacksReceived?.length) {
-      const defeatSource = globalScene.getPokemonById(pokemon.turnData.attacksReceived[0].sourceId);
+      const defeatSource = this.source;
+
       if (defeatSource?.isOnField()) {
         applyPostVictoryAbAttrs(PostVictoryAbAttr, defeatSource);
         const pvmove = allMoves[pokemon.turnData.attacksReceived[0].move];

src/test/moves/fell_stinger.test.ts

@@ -0,0 +1,198 @@
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+import GameManager from "../utils/gameManager";
+import { Species } from "#enums/species";
+import { Abilities } from "#enums/abilities";
+import { Moves } from "#enums/moves";
+import { Stat } from "#enums/stat";
+import { StatusEffect } from "#app/enums/status-effect";
+import { WeatherType } from "#app/enums/weather-type";
+import { allMoves } from "#app/data/move";
+
+
+describe("Moves - Fell Stinger", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+
+    game.override.battleType("single")
+      .moveset([
+        Moves.FELL_STINGER,
+        Moves.SALT_CURE,
+        Moves.BIND,
+        Moves.LEECH_SEED
+      ])
+      .startingLevel(50)
+      .disableCrits()
+      .enemyAbility(Abilities.STURDY)
+      .enemySpecies(Species.HYPNO)
+      .enemyMoveset(Moves.SPLASH)
+      .enemyLevel(5);
+  });
+
+  it("should not grant stat boost if opponent gets KO'd by recoil", async () => {
+    game.override.enemyMoveset([ Moves.DOUBLE_EDGE ]);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.FELL_STINGER);
+
+    await game.phaseInterceptor.to("VictoryPhase");
+
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should not grant stat boost if enemy is KO'd by status effect", async () => {
+    game.override
+      .enemyMoveset(Moves.SPLASH)
+      .enemyStatusEffect(StatusEffect.BURN);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.FELL_STINGER);
+
+    await game.phaseInterceptor.to("VictoryPhase");
+
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should not grant stat boost if enemy is KO'd by damaging weather", async () => {
+    game.override.weather(WeatherType.HAIL);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+
+    game.move.select(Moves.FELL_STINGER);
+
+    await game.phaseInterceptor.to("VictoryPhase");
+
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should not grant stat boost if enemy is KO'd by Dry Skin + Harsh Sunlight", async () => {
+    game.override
+      .enemyPassiveAbility(Abilities.STURDY)
+      .enemyAbility(Abilities.DRY_SKIN)
+      .weather(WeatherType.HARSH_SUN);
+
+    await game.challengeMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+
+    game.move.select(Moves.FELL_STINGER);
+
+    await game.phaseInterceptor.to("VictoryPhase");
+
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should not grant stat boost if enemy is saved by Reviver Seed", async () => {
+    game.override
+      .enemyAbility(Abilities.BALL_FETCH)
+      .enemyHeldItems([{ name: "REVIVER_SEED" }]);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+    game.move.select(Moves.FELL_STINGER);
+
+    await game.phaseInterceptor.to("TurnEndPhase");
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should not grant stat boost if enemy is KO'd by Salt Cure", async () => {
+    game.override.battleType("double")
+      .startingLevel(5);
+    const saltCure = allMoves[Moves.SALT_CURE];
+    const fellStinger = allMoves[Moves.FELL_STINGER];
+    vi.spyOn(saltCure, "accuracy", "get").mockReturnValue(100);
+    vi.spyOn(fellStinger, "power", "get").mockReturnValue(50000);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+    const leftEnemy = game.scene.getEnemyField()[0]!;
+
+    //  Turn 1: set Salt Cure, enemy splashes and does nothing
+    game.move.select(Moves.SALT_CURE, 0, leftEnemy.getBattlerIndex());
+
+    //  Turn 2: enemy Endures Fell Stinger, then dies to Salt Cure
+    await game.toNextTurn();
+    expect(leftEnemy.isFainted()).toBe(false);
+    leftEnemy.heal(leftEnemy.getMaxHp());
+    game.move.select(Moves.FELL_STINGER);
+    await game.toNextTurn();
+
+    expect(leftEnemy.isFainted()).toBe(true);
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should not grant stat boost if enemy dies to Bind or a similar effect", async () => {
+    game.override.battleType("double")
+      .startingLevel(5);
+    vi.spyOn(allMoves[Moves.BIND], "accuracy", "get").mockReturnValue(100);
+    vi.spyOn(allMoves[Moves.FELL_STINGER], "power", "get").mockReturnValue(50000);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+    const leftEnemy = game.scene.getEnemyField()[0]!;
+
+    // Turn 1: set Bind, enemy splashes and does nothing
+    game.move.select(Moves.BIND, 0, leftEnemy.getBattlerIndex());
+
+    // Turn 2: enemy Endures Fell Stinger, then dies to Bind
+    await game.toNextTurn();
+    expect(leftEnemy.isFainted()).toBe(false);
+    leftEnemy.heal(leftEnemy.getMaxHp());
+    game.move.select(Moves.FELL_STINGER, 0, leftEnemy.getBattlerIndex());
+    await game.toNextTurn();
+
+    expect(leftEnemy.isFainted()).toBe(true);
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should not grant stat boost if enemy dies to Leech Seed", async () => {
+    game.override.battleType("double")
+      .startingLevel(5);
+    vi.spyOn(allMoves[Moves.LEECH_SEED], "accuracy", "get").mockReturnValue(100);
+    vi.spyOn(allMoves[Moves.FELL_STINGER], "power", "get").mockReturnValue(50000);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon()!;
+    const leftEnemy = game.scene.getEnemyField()[0]!;
+
+    // Turn 1: set Leech Seed, enemy splashes and does nothing
+    game.move.select(Moves.LEECH_SEED, 0, leftEnemy.getBattlerIndex());
+
+    // Turn 2: enemy Endures Fell Stinger, then dies to Leech Seed
+    await game.toNextTurn();
+    expect(leftEnemy.isFainted()).toBe(false);
+    leftEnemy.heal(leftEnemy.getMaxHp());
+    game.move.select(Moves.FELL_STINGER, 0, leftEnemy.getBattlerIndex());
+    await game.toNextTurn();
+
+    expect(leftEnemy.isFainted()).toBe(true);
+    expect(leadPokemon.getStatStage(Stat.ATK)).toBe(0);
+  });
+
+  it("should grant stat boost if enemy dies directly to hit", async () => {
+    game.override.enemyAbility(Abilities.KLUTZ);
+
+    await game.classicMode.startBattle([ Species.LEAVANNY ]);
+    const leadPokemon = game.scene.getPlayerPokemon();
+    game.move.select(Moves.FELL_STINGER);
+
+    await game.phaseInterceptor.to("TurnEndPhase");
+
+    expect(leadPokemon?.getStatStage(Stat.ATK)).toBe(3);
+  });
+});