[P2] Nightmare triggers at turn end instead of after move (#4702)

src/data/battler-tags.ts

@@ -838,7 +838,7 @@ export class SeedTag extends BattlerTag {
 
 export class NightmareTag extends BattlerTag {
   constructor() {
-    super(BattlerTagType.NIGHTMARE, BattlerTagLapseType.AFTER_MOVE, 1, Moves.NIGHTMARE);
+    super(BattlerTagType.NIGHTMARE, BattlerTagLapseType.TURN_END, 1, Moves.NIGHTMARE);
   }
 
   onAdd(pokemon: Pokemon): void {

src/test/moves/nightmare.test.ts

@@ -0,0 +1,54 @@
+import { CommandPhase } from "#app/phases/command-phase";
+import { TurnInitPhase } from "#app/phases/turn-init-phase";
+import { Abilities } from "#enums/abilities";
+import { Moves } from "#enums/moves";
+import { Species } from "#enums/species";
+import GameManager from "#test/utils/gameManager";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it } from "vitest";
+import { StatusEffect } from "#app/data/status-effect";
+
+describe("Moves - Nightmare", () => {
+  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")
+      .enemySpecies(Species.RATTATA)
+      .enemyMoveset(Moves.SPLASH)
+      .enemyAbility(Abilities.BALL_FETCH)
+      .enemyStatusEffect(StatusEffect.SLEEP)
+      .startingLevel(5)
+      .moveset([ Moves.NIGHTMARE, Moves.SPLASH ]);
+  });
+
+  it("lowers enemy hp by 1/4 each turn while asleep", async () => {
+    await game.classicMode.startBattle([ Species.HYPNO ]);
+
+    const enemyPokemon = game.scene.getEnemyPokemon()!;
+    const enemyMaxHP = enemyPokemon.hp;
+    game.move.select(Moves.NIGHTMARE);
+    await game.phaseInterceptor.to(TurnInitPhase);
+
+    expect(enemyPokemon.hp).toBe(enemyMaxHP - Math.floor(enemyMaxHP / 4));
+
+    // take a second turn to make sure damage occurs again
+    await game.phaseInterceptor.to(CommandPhase);
+    game.move.select(Moves.SPLASH);
+
+    await game.phaseInterceptor.to(TurnInitPhase);
+    expect(enemyPokemon.hp).toBe(enemyMaxHP - Math.floor(enemyMaxHP / 4) - Math.floor(enemyMaxHP / 4));
+  });
+});