[P2 Bug] Fix sturdy and endure causing an extra stat boost to boss Pokemon (#4347)

* [bug] fix sturdy and endure causing an extra stat boost to boss Pokemon

* [doc] add doc for handleBossSegmentCleared

src/field/pokemon.ts

@@ -4749,8 +4749,15 @@ export class EnemyPokemon extends Pokemon {
     return true;
   }
 
+  /**
+   * Go through a boss' health segments and give stats boosts for each newly cleared segment
+   * The base boost is 1 to a random stat that's not already maxed out per broken shield
+   * For Pokemon with 3 health segments or more, breaking the last shield gives +2 instead
+   * For Pokemon with 5 health segments or more, breaking the last two shields give +2 each
+   * @param segmentIndex index of the segment to get down to (0 = no shield left, 1 = 1 shield left, etc.)
+   */
   handleBossSegmentCleared(segmentIndex: integer): void {
-    while (segmentIndex - 1 < this.bossSegmentIndex) {
+    while (this.bossSegmentIndex > 0 && segmentIndex - 1 < this.bossSegmentIndex) {
       // Filter out already maxed out stat stages and weigh the rest based on existing stats
       const leftoverStats = EFFECTIVE_STATS.filter((s: EffectiveStat) => this.getStatStage(s) < 6);
       const statWeights = leftoverStats.map((s: EffectiveStat) => this.getStat(s, false));

src/test/boss-pokemon.test.ts

@@ -33,7 +33,7 @@ describe("Boss Pokemon / Shields", () => {
       .enemyMoveset(Moves.SPLASH)
       .enemyHeldItems([])
       .startingLevel(1000)
-      .moveset([Moves.FALSE_SWIPE, Moves.SUPER_FANG, Moves.SPLASH])
+      .moveset([Moves.FALSE_SWIPE, Moves.SUPER_FANG, Moves.SPLASH, Moves.PSYCHIC])
       .ability(Abilities.NO_GUARD);
   });
 
@@ -196,6 +196,28 @@ describe("Boss Pokemon / Shields", () => {
 
   });
 
+  it("the boss enduring does not proc an extra stat boost", async () => {
+    game.override
+      .enemyHealthSegments(2)
+      .enemyAbility(Abilities.STURDY);
+
+    await game.classicMode.startBattle([ Species.MEWTWO ]);
+
+    const enemyPokemon = game.scene.getEnemyPokemon()!;
+    expect(enemyPokemon.isBoss()).toBe(true);
+    expect(enemyPokemon.bossSegments).toBe(2);
+    expect(getTotalStatStageBoosts(enemyPokemon)).toBe(0);
+
+    game.move.select(Moves.PSYCHIC);
+    await game.toNextTurn();
+
+    // Enemy survived with Sturdy
+    expect(enemyPokemon.bossSegmentIndex).toBe(0);
+    expect(enemyPokemon.hp).toBe(1);
+    expect(getTotalStatStageBoosts(enemyPokemon)).toBe(1);
+
+  }, TIMEOUT);
+
   /**
    * Gets the sum of the effective stat stage boosts for the given Pokemon
    * @param enemyPokemon the pokemon to get stats from