[Bug] Fix Ball Fetch activating on enemy Pokemon (#6777)

src/data/abilities/ability.ts

@@ -2707,6 +2707,7 @@ export class PostSummonAddArenaTagAbAttr extends PostSummonAbAttr {
   private readonly turnCount: number;
   private readonly side?: ArenaTagSide;
   private readonly quiet?: boolean;
+  // TODO: This should not need to track the source ID in a tempvar
   private sourceId: number;
 
   constructor(showAbility: boolean, tagType: ArenaTagType, turnCount: number, side?: ArenaTagSide, quiet?: boolean) {
@@ -2741,6 +2742,7 @@ export class PostSummonMessageAbAttr extends PostSummonAbAttr {
   }
 }
 
+// TODO: This should be merged with message func
 export class PostSummonUnnamedMessageAbAttr extends PostSummonAbAttr {
   //Attr doesn't force pokemon name on the message
   private readonly message: string;
@@ -2811,13 +2813,13 @@ export class PostSummonStatStageChangeAbAttr extends PostSummonAbAttr {
   private readonly selfTarget: boolean;
   private readonly intimidate: boolean;
 
-  constructor(stats: readonly BattleStat[], stages: number, selfTarget?: boolean, intimidate?: boolean) {
+  constructor(stats: readonly BattleStat[], stages: number, selfTarget = false, intimidate = true) {
     super(true);
 
     this.stats = stats;
     this.stages = stages;
-    this.selfTarget = !!selfTarget;
-    this.intimidate = !!intimidate;
+    this.selfTarget = selfTarget;
+    this.intimidate = intimidate;
   }
 
   override apply({ pokemon, simulated }: AbAttrBaseParams): void {
@@ -5012,25 +5014,26 @@ export class PostTurnHurtIfSleepingAbAttr extends PostTurnAbAttr {
  */
 export class FetchBallAbAttr extends PostTurnAbAttr {
   override canApply({ simulated, pokemon }: AbAttrBaseParams): boolean {
-    return !simulated && globalScene.currentBattle.lastUsedPokeball != null && !!pokemon.isPlayer;
+    return !simulated && globalScene.currentBattle.lastUsedPokeball != null && pokemon.isPlayer();
   }
 
   /**
    * Adds the last used Pokeball back into the player's inventory
    */
   override apply({ pokemon }: AbAttrBaseParams): void {
-    const lastUsed = globalScene.currentBattle.lastUsedPokeball;
-    globalScene.pokeballCounts[lastUsed!]++;
+    const lastUsed = globalScene.currentBattle.lastUsedPokeball!;
+    globalScene.pokeballCounts[lastUsed]++;
     globalScene.currentBattle.lastUsedPokeball = null;
     globalScene.phaseManager.queueMessage(
       i18next.t("abilityTriggers:fetchBall", {
         pokemonNameWithAffix: getPokemonNameWithAffix(pokemon),
-        pokeballName: getPokeballName(lastUsed!),
+        pokeballName: getPokeballName(lastUsed),
       }),
     );
   }
 }
 
+// TODO: Remove this and just replace it with applying `PostSummonChangeTerrainAbAttr` again
 export class PostBiomeChangeAbAttr extends AbAttr {
   private declare readonly _: never;
 }
@@ -5055,6 +5058,7 @@ export class PostBiomeChangeWeatherChangeAbAttr extends PostBiomeChangeAbAttr {
   }
 }
 
+// TODO: Remove this and just replace it with applying `PostSummonChangeTerrainAbAttr` again
 /** @sealed */
 export class PostBiomeChangeTerrainChangeAbAttr extends PostBiomeChangeAbAttr {
   private readonly terrainType: TerrainType;

test/abilities/ball-fetch.test.ts

@@ -0,0 +1,92 @@
+/*
+ * SPDX-FileCopyrightText: 2024-2025 Pagefault Games
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { getPokemonNameWithAffix } from "#app/messages";
+import { getPokeballName } from "#data/pokeball";
+import { AbilityId } from "#enums/ability-id";
+import { MoveId } from "#enums/move-id";
+import { PokeballType } from "#enums/pokeball";
+import { SpeciesId } from "#enums/species-id";
+import { GameManager } from "#test/test-utils/game-manager";
+import i18next from "i18next";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+
+// NB: These tests pass when done locally, but we currently have no mechanism to make catches fail
+// due to battle scene RNG overrides making ball shake checks always succeed.
+//
+// TODO: Enable suite once `AttemptCapturePhase` is made sane
+describe.todo("Ability - Ball Fetch", () => {
+  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
+      .ability(AbilityId.BALL_FETCH)
+      .battleStyle("single")
+      .criticalHits(false)
+      .enemySpecies(SpeciesId.MAGIKARP)
+      .enemyMoveset(MoveId.SPLASH)
+      .startingLevel(100)
+      .enemyLevel(100);
+  });
+
+  it("should restore the user's first failed ball throw at end of turn", async () => {
+    await game.classicMode.startBattle([SpeciesId.FEEBAS]);
+
+    const feebas = game.field.getPlayerPokemon();
+    const karp = game.field.getEnemyPokemon();
+
+    vi.spyOn(karp.species, "catchRate", "get").mockReturnValue(0);
+
+    game.doThrowPokeball(PokeballType.POKEBALL);
+    await game.toEndOfTurn(false);
+
+    expect(game.scene.pokeballCounts[PokeballType.POKEBALL]).toBe(4);
+
+    await game.toEndOfTurn();
+
+    expect(feebas).toHaveAbilityApplied(AbilityId.BALL_FETCH);
+    expect(game.scene.pokeballCounts[PokeballType.POKEBALL]).toBe(5);
+    expect(game).toHaveShownMessage(
+      i18next.t("abilityTriggers:fetchBall", {
+        pokemonNameWithAffix: getPokemonNameWithAffix(feebas),
+        pokeballName: getPokeballName(PokeballType.POKEBALL),
+      }),
+    );
+  });
+
+  it("should not work on enemies", async () => {
+    game.override.ability(AbilityId.AIR_LOCK).enemyAbility(AbilityId.BALL_FETCH);
+    await game.classicMode.startBattle([SpeciesId.FEEBAS]);
+
+    const karp = game.field.getEnemyPokemon();
+
+    vi.spyOn(karp.species, "catchRate", "get").mockReturnValue(0);
+
+    game.doThrowPokeball(PokeballType.POKEBALL);
+    await game.toEndOfTurn(false);
+
+    expect(game.scene.pokeballCounts[PokeballType.POKEBALL]).toBe(4);
+
+    await game.toEndOfTurn();
+
+    // did nothing; still at 4 balls
+    expect(karp).not.toHaveAbilityApplied(AbilityId.BALL_FETCH);
+    expect(game.scene.pokeballCounts[PokeballType.POKEBALL]).toBe(4);
+  });
+});

test/test-utils/game-manager.ts

@@ -372,9 +372,13 @@ export class GameManager {
     console.log("==================[New Turn]==================");
   }
 
-  /** Transition to the {@linkcode TurnEndPhase | end of the current turn}. */
-  async toEndOfTurn() {
-    await this.phaseInterceptor.to("TurnEndPhase");
+  /**
+   * Transition to the {@linkcode TurnEndPhase | end of the current turn}.
+   * @param endTurn - Whether to run the `TurnEndPhase` or not; default `true`
+   * @returns A Promise that resolves once the current turn has ended.
+   */
+  async toEndOfTurn(endTurn = true): Promise<void> {
+    await this.phaseInterceptor.to("TurnEndPhase", endTurn);
     console.log("==================[End of Turn]==================");
   }