[Move] Triple Arrows effect chance for stat change is now 50% (#4543)

* Triple Arrows effect chance for stat change is now properly 50%

* Add tsdocs to `StatStageChangeAttr`

* Add test for Serene Grace interaction

* Fix linting

---------

Co-authored-by: Mumble <171087428+frutescens@users.noreply.github.com>

src/data/move.ts

@@ -970,13 +970,16 @@ export class MoveEffectAttr extends MoveAttr {
   public lastHitOnly: boolean;
   /** Should this effect only apply on the first target hit? */
   public firstTargetOnly: boolean;
+  /** Overrides the secondary effect chance for this attr if set. */
+  public effectChanceOverride?: number;
 
-  constructor(selfTarget?: boolean, trigger?: MoveEffectTrigger, firstHitOnly: boolean = false, lastHitOnly: boolean = false, firstTargetOnly: boolean = false) {
+  constructor(selfTarget?: boolean, trigger?: MoveEffectTrigger, firstHitOnly: boolean = false, lastHitOnly: boolean = false, firstTargetOnly: boolean = false, effectChanceOverride?: number) {
     super(selfTarget);
-    this.trigger = trigger !== undefined ? trigger : MoveEffectTrigger.POST_APPLY;
+    this.trigger = trigger ?? MoveEffectTrigger.POST_APPLY;
     this.firstHitOnly = firstHitOnly;
     this.lastHitOnly = lastHitOnly;
     this.firstTargetOnly = firstTargetOnly;
+    this.effectChanceOverride = effectChanceOverride;
   }
 
   /**
@@ -1001,15 +1004,15 @@ export class MoveEffectAttr extends MoveAttr {
 
   /**
    * Gets the used move's additional effect chance.
-   * If user's ability has MoveEffectChanceMultiplierAbAttr or IgnoreMoveEffectsAbAttr modifies the base chance.
+   * Chance is modified by {@linkcode MoveEffectChanceMultiplierAbAttr} and {@linkcode IgnoreMoveEffectsAbAttr}.
    * @param user {@linkcode Pokemon} using this move
-   * @param target {@linkcode Pokemon} target of this move
+   * @param target {@linkcode Pokemon | Target} of this move
    * @param move {@linkcode Move} being used
-   * @param selfEffect {@linkcode Boolean} if move targets user.
-   * @returns Move chance value.
+   * @param selfEffect `true` if move targets user.
+   * @returns Move effect chance value.
    */
   getMoveChance(user: Pokemon, target: Pokemon, move: Move, selfEffect?: Boolean, showAbility?: Boolean): integer {
-    const moveChance = new Utils.NumberHolder(move.chance);
+    const moveChance = new Utils.NumberHolder(this.effectChanceOverride ?? move.chance);
 
     applyAbAttrs(MoveEffectChanceMultiplierAbAttr, user, null, false, moveChance, move, target, selfEffect, showAbility);
 
@@ -2752,14 +2755,17 @@ export class AwaitCombinedPledgeAttr extends OverrideMoveEffectAttr {
 
 /**
  * Attribute used for moves that change stat stages
- * @param stats {@linkcode BattleStat} array of stats to be changed
- * @param stages stages by which to change the stats, from -6 to 6
- * @param selfTarget whether the changes are applied to the user (true) or the target (false)
- * @param condition {@linkcode MoveConditionFunc} optional condition to trigger the stat change
- * @param firstHitOnly whether the stat change only applies on the first hit of a multi hit move
- * @param moveEffectTrigger {@linkcode MoveEffectTrigger} the trigger for the effect to take place
- * @param firstTargetOnly whether, if this is a multi target move, to only apply the effect after the first target is hit, rather than once for each target
- * @param lastHitOnly whether the effect should only apply after the last hit of a multi hit move
+ *
+ * @param stats {@linkcode BattleStat} Array of stat(s) to change
+ * @param stages How many stages to change the stat(s) by, [-6, 6]
+ * @param selfTarget `true` if the move is self-targetting
+ * @param condition {@linkcode MoveConditionFunc} Optional condition to be checked in order to apply the changes
+ * @param showMessage `true` to display a message; default `true`
+ * @param firstHitOnly `true` if only the first hit of a multi hit move should cause a stat stage change; default `false`
+ * @param moveEffectTrigger {@linkcode MoveEffectTrigger} When the stat change should trigger; default {@linkcode MoveEffectTrigger.HIT}
+ * @param firstTargetOnly `true` if a move that hits multiple pokemon should only trigger the stat change if it hits at least one pokemon, rather than once per hit pokemon; default `false`
+ * @param lastHitOnly `true` if the effect should only apply after the last hit of a multi hit move; default `false`
+ * @param effectChanceOverride Will override the move's normal secondary effect chance if specified
  *
  * @extends MoveEffectAttr
  * @see {@linkcode apply}
@@ -2767,14 +2773,14 @@ export class AwaitCombinedPledgeAttr extends OverrideMoveEffectAttr {
 export class StatStageChangeAttr extends MoveEffectAttr {
   public stats: BattleStat[];
   public stages: integer;
-  private condition: MoveConditionFunc | null;
+  private condition?: MoveConditionFunc | null;
   private showMessage: boolean;
 
-  constructor(stats: BattleStat[], stages: integer, selfTarget?: boolean, condition?: MoveConditionFunc | null, showMessage: boolean = true, firstHitOnly: boolean = false, moveEffectTrigger: MoveEffectTrigger = MoveEffectTrigger.HIT, firstTargetOnly: boolean = false, lastHitOnly: boolean = false) {
-    super(selfTarget, moveEffectTrigger, firstHitOnly, lastHitOnly, firstTargetOnly);
+  constructor(stats: BattleStat[], stages: integer, selfTarget?: boolean, condition?: MoveConditionFunc | null, showMessage: boolean = true, firstHitOnly: boolean = false, moveEffectTrigger: MoveEffectTrigger = MoveEffectTrigger.HIT, firstTargetOnly: boolean = false, lastHitOnly: boolean = false, effectChanceOverride?: number) {
+    super(selfTarget, moveEffectTrigger, firstHitOnly, lastHitOnly, firstTargetOnly, effectChanceOverride);
     this.stats = stats;
     this.stages = stages;
-    this.condition = condition!; // TODO: is this bang correct?
+    this.condition = condition;
     this.showMessage = showMessage;
   }
 
@@ -9556,9 +9562,8 @@ export function initMoves() {
     new AttackMove(Moves.TRIPLE_ARROWS, Type.FIGHTING, MoveCategory.PHYSICAL, 90, 100, 10, 30, 0, 8)
       .makesContact(false)
       .attr(HighCritAttr)
-      .attr(StatStageChangeAttr, [ Stat.DEF ], -1)
-      .attr(FlinchAttr)
-      .partial(),
+      .attr(StatStageChangeAttr, [ Stat.DEF ], -1, undefined, undefined, undefined, undefined, undefined, undefined, undefined, 50)
+      .attr(FlinchAttr),
     new AttackMove(Moves.INFERNAL_PARADE, Type.GHOST, MoveCategory.SPECIAL, 60, 100, 15, 30, 0, 8)
       .attr(StatusEffectAttr, StatusEffect.BURN)
       .attr(MovePowerMultiplierAttr, (user, target, move) => target.status ? 2 : 1),

src/test/moves/triple_arrows.test.ts

@@ -0,0 +1,60 @@
+import { allMoves, FlinchAttr, StatStageChangeAttr } from "#app/data/move";
+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, vi } from "vitest";
+
+describe("Moves - Triple Arrows", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+  const tripleArrows = allMoves[Moves.TRIPLE_ARROWS];
+  const flinchAttr = tripleArrows.getAttrs(FlinchAttr)[0];
+  const defDropAttr = tripleArrows.getAttrs(StatStageChangeAttr)[0];
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+    game.override
+      .ability(Abilities.BALL_FETCH)
+      .moveset([ Moves.TRIPLE_ARROWS ])
+      .battleType("single")
+      .enemySpecies(Species.MAGIKARP)
+      .enemyAbility(Abilities.STURDY)
+      .enemyMoveset(Moves.SPLASH);
+
+    vi.spyOn(flinchAttr, "getMoveChance");
+    vi.spyOn(defDropAttr, "getMoveChance");
+  });
+
+  it("has a 30% flinch chance and 50% defense drop chance", async () => {
+    await game.classicMode.startBattle([ Species.FEEBAS ]);
+
+    game.move.select(Moves.TRIPLE_ARROWS);
+    await game.phaseInterceptor.to("BerryPhase");
+
+    expect(flinchAttr.getMoveChance).toHaveReturnedWith(30);
+    expect(defDropAttr.getMoveChance).toHaveReturnedWith(50);
+  });
+
+  it("is affected normally by Serene Grace", async () => {
+    game.override.ability(Abilities.SERENE_GRACE);
+    await game.classicMode.startBattle([ Species.FEEBAS ]);
+
+    game.move.select(Moves.TRIPLE_ARROWS);
+    await game.phaseInterceptor.to("BerryPhase");
+
+    expect(flinchAttr.getMoveChance).toHaveReturnedWith(60);
+    expect(defDropAttr.getMoveChance).toHaveReturnedWith(100);
+  });
+});