changing tests around and fixing the issue

src/data/battler-tags.ts

@@ -1085,10 +1085,6 @@ export class OctolockTag extends TrappedTag {
     super(BattlerTagType.OCTOLOCK, BattlerTagLapseType.TURN_END, 1, Moves.OCTOLOCK, sourceId);
   }
 
-  canAdd(pokemon: Pokemon): boolean {
-    return !pokemon.getTag(BattlerTagType.OCTOLOCK);
-  }
-
   lapse(pokemon: Pokemon, lapseType: BattlerTagLapseType): boolean {
     const shouldLapse = lapseType !== BattlerTagLapseType.CUSTOM || super.lapse(pokemon, lapseType);
 

src/test/battlerTags/octolock.test.ts

@@ -1,9 +1,8 @@
 import BattleScene from "#app/battle-scene";
 import { describe, expect, it, vi } from "vitest";
 import Pokemon from "#app/field/pokemon";
-import { BattlerTag, BattlerTagLapseType, OctolockTag, TrappedTag } from "#app/data/battler-tags";
+import { BattlerTagLapseType, OctolockTag, TrappedTag } from "#app/data/battler-tags";
 import { StatStageChangePhase } from "#app/phases/stat-stage-change-phase";
-import { BattlerTagType } from "#app/enums/battler-tag-type";
 import { Stat } from "#enums/stat";
 
 vi.mock("#app/battle-scene.js");
@@ -33,30 +32,4 @@ describe("BattlerTag - OctolockTag", () => {
   it ("traps its target (extends TrappedTag)", async () => {
     expect(new OctolockTag(1)).toBeInstanceOf(TrappedTag);
   });
-
-  it("can be added to pokemon who are not octolocked", async => {
-    const mockPokemon = {
-      getTag: vi.fn().mockReturnValue(undefined) as Pokemon["getTag"],
-    } as Pokemon;
-
-    const subject = new OctolockTag(1);
-
-    expect(subject.canAdd(mockPokemon)).toBeTruthy();
-
-    expect(mockPokemon.getTag).toHaveBeenCalledTimes(1);
-    expect(mockPokemon.getTag).toHaveBeenCalledWith(BattlerTagType.OCTOLOCK);
-  });
-
-  it("cannot be added to pokemon who are octolocked", async => {
-    const mockPokemon = {
-      getTag: vi.fn().mockReturnValue(new BattlerTag(null!, null!, null!, null!)) as Pokemon["getTag"],
-    } as Pokemon;
-
-    const subject = new OctolockTag(1);
-
-    expect(subject.canAdd(mockPokemon)).toBeFalsy();
-
-    expect(mockPokemon.getTag).toHaveBeenCalledTimes(1);
-    expect(mockPokemon.getTag).toHaveBeenCalledWith(BattlerTagType.OCTOLOCK);
-  });
 });

src/test/moves/octolock.test.ts

@@ -9,6 +9,7 @@ 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 { BattlerIndex } from "#app/battle";
 
 describe("Moves - Octolock", () => {
   let phaserGame: Phaser.Game;
@@ -113,4 +114,25 @@ describe("Moves - Octolock", () => {
     await game.phaseInterceptor.to(MoveEndPhase);
     expect(enemyPokemon.findTag(t => t instanceof TrappedTag)).toBeDefined();
   });
+
+  it("does not work on ghost type pokemon", async () => {
+    game.override.enemySpecies(Species.GRAPPLOCT);
+    game.override.enemyMoveset(Moves.OCTOLOCK);
+    game.override.moveset(Moves.SPLASH);
+    await game.classicMode.startBattle([ Species.GASTLY ]);
+
+    const playerPokemon = game.scene.getPlayerPokemon()!;
+
+    // before Octolock - player should not be trapped
+    expect(playerPokemon.findTag(t => t instanceof TrappedTag)).toBeUndefined();
+
+    game.forceEnemyMove(Moves.OCTOLOCK, BattlerIndex.PLAYER);
+    game.move.select(Moves.OCTOLOCK);
+    game.toNextTurn();
+
+    // after Octolock - player should still not be trapped, and no stat loss
+    expect(playerPokemon.findTag(t => t instanceof TrappedTag)).toBeUndefined();
+    expect(playerPokemon.getStatStage(Stat.DEF)).toBe(0);
+    expect(playerPokemon.getStatStage(Stat.SPDEF)).toBe(0);
+  });
 });