[P1][Beta] Fix FormChangePhase being broken by EvolutionPhase refactor (#4795)

* [P1][Beta] Fix FormChangePhase being broken by EvolutionPhase refactor

* Apply suggested changes to added test

src/phases/evolution-phase.ts

@@ -39,8 +39,6 @@ export class EvolutionPhase extends Phase {
     this.pokemon = pokemon;
     this.evolution = evolution;
     this.lastLevel = lastLevel;
-    this.evolutionBgm = this.scene.playSoundWithoutBgm("evolution");
-    this.preEvolvedPokemonName = getPokemonNameWithAffix(this.pokemon);
   }
 
   validate(): boolean {
@@ -62,9 +60,9 @@ export class EvolutionPhase extends Phase {
 
       this.scene.fadeOutBgm(undefined, false);
 
-      const evolutionHandler = this.scene.ui.getHandler() as EvolutionSceneHandler;
+      this.evolutionHandler = this.scene.ui.getHandler() as EvolutionSceneHandler;
 
-      this.evolutionContainer = evolutionHandler.evolutionContainer;
+      this.evolutionContainer = this.evolutionHandler.evolutionContainer;
 
       this.evolutionBaseBg = this.scene.add.image(0, 0, "default_bg");
       this.evolutionBaseBg.setOrigin(0, 0);
@@ -117,14 +115,12 @@ export class EvolutionPhase extends Phase {
           sprite.pipelineData[k] = this.pokemon.getSprite().pipelineData[k];
         });
       });
-
+      this.preEvolvedPokemonName = getPokemonNameWithAffix(this.pokemon);
       this.doEvolution();
     });
   }
 
   doEvolution(): void {
-    this.evolutionHandler = this.scene.ui.getHandler() as EvolutionSceneHandler;
-
     this.scene.ui.showText(i18next.t("menu:evolving", { pokemonName: this.preEvolvedPokemonName }), null, () => {
       this.pokemon.cry();
 
@@ -145,6 +141,7 @@ export class EvolutionPhase extends Phase {
         });
 
         this.scene.time.delayedCall(1000, () => {
+          this.evolutionBgm = this.scene.playSoundWithoutBgm("evolution");
           this.scene.tweens.add({
             targets: this.evolutionBgOverlay,
             alpha: 1,

src/test/phases/form-change-phase.test.ts

@@ -0,0 +1,60 @@
+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 { Type } from "#app/data/type";
+import { generateModifierType } from "#app/data/mystery-encounters/utils/encounter-phase-utils";
+import { modifierTypes } from "#app/modifier/modifier-type";
+
+describe("Form Change Phase", () => {
+  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
+      .moveset([ Moves.SPLASH ])
+      .ability(Abilities.BALL_FETCH)
+      .battleType("single")
+      .disableCrits()
+      .enemySpecies(Species.MAGIKARP)
+      .enemyAbility(Abilities.BALL_FETCH)
+      .enemyMoveset(Moves.SPLASH);
+  });
+
+  it("Zacian should successfully change into Crowned form", async () => {
+    await game.classicMode.startBattle([ Species.ZACIAN ]);
+
+    // Before the form change: Should be Hero form
+    const zacian = game.scene.getPlayerParty()[0];
+    expect(zacian.getFormKey()).toBe("hero-of-many-battles");
+    expect(zacian.getTypes()).toStrictEqual([ Type.FAIRY ]);
+    expect(zacian.calculateBaseStats()).toStrictEqual([ 92, 120, 115, 80, 115, 138 ]);
+
+    // Give Zacian a Rusted Sword
+    const rustedSwordType = generateModifierType(game.scene, modifierTypes.RARE_FORM_CHANGE_ITEM)!;
+    const rustedSword = rustedSwordType.newModifier(zacian);
+    await game.scene.addModifier(rustedSword);
+
+    game.move.select(Moves.SPLASH);
+    await game.toNextTurn();
+
+    // After the form change: Should be Crowned form
+    expect(game.phaseInterceptor.log.includes("FormChangePhase")).toBe(true);
+    expect(zacian.getFormKey()).toBe("crowned");
+    expect(zacian.getTypes()).toStrictEqual([ Type.FAIRY, Type.STEEL ]);
+    expect(zacian.calculateBaseStats()).toStrictEqual([ 92, 150, 115, 80, 115, 148 ]);
+  });
+});

src/test/utils/helpers/classicModeHelper.ts

@@ -35,7 +35,7 @@ export class ClassicModeHelper extends GameManagerHelper {
       selectStarterPhase.initBattle(starters);
     });
 
-    await this.game.phaseInterceptor.run(EncounterPhase);
+    await this.game.phaseInterceptor.to(EncounterPhase);
     if (overrides.OPP_HELD_ITEMS_OVERRIDE.length === 0 && this.game.override.removeEnemyStartingItems) {
       this.game.removeEnemyHeldItems();
     }

src/test/utils/phaseInterceptor.ts

@@ -12,6 +12,7 @@ import { EndEvolutionPhase } from "#app/phases/end-evolution-phase";
 import { EnemyCommandPhase } from "#app/phases/enemy-command-phase";
 import { EvolutionPhase } from "#app/phases/evolution-phase";
 import { FaintPhase } from "#app/phases/faint-phase";
+import { FormChangePhase } from "#app/phases/form-change-phase";
 import { LearnMovePhase } from "#app/phases/learn-move-phase";
 import { LevelCapPhase } from "#app/phases/level-cap-phase";
 import { LoginPhase } from "#app/phases/login-phase";
@@ -67,7 +68,6 @@ type PhaseClass =
   | typeof LoginPhase
   | typeof TitlePhase
   | typeof SelectGenderPhase
-  | typeof EncounterPhase
   | typeof NewBiomeEncounterPhase
   | typeof SelectStarterPhase
   | typeof PostSummonPhase
@@ -102,6 +102,7 @@ type PhaseClass =
   | typeof SwitchPhase
   | typeof SwitchSummonPhase
   | typeof PartyHealPhase
+  | typeof FormChangePhase
   | typeof EvolutionPhase
   | typeof EndEvolutionPhase
   | typeof LevelCapPhase
@@ -114,13 +115,13 @@ type PhaseClass =
   | typeof PostMysteryEncounterPhase
   | typeof ModifierRewardPhase
   | typeof PartyExpPhase
-  | typeof ExpPhase;
+  | typeof ExpPhase
+  | typeof EncounterPhase;
 
 type PhaseString =
   | "LoginPhase"
   | "TitlePhase"
   | "SelectGenderPhase"
-  | "EncounterPhase"
   | "NewBiomeEncounterPhase"
   | "SelectStarterPhase"
   | "PostSummonPhase"
@@ -155,6 +156,7 @@ type PhaseString =
   | "SwitchPhase"
   | "SwitchSummonPhase"
   | "PartyHealPhase"
+  | "FormChangePhase"
   | "EvolutionPhase"
   | "EndEvolutionPhase"
   | "LevelCapPhase"
@@ -167,7 +169,8 @@ type PhaseString =
   | "PostMysteryEncounterPhase"
   | "ModifierRewardPhase"
   | "PartyExpPhase"
-  | "ExpPhase";
+  | "ExpPhase"
+  | "EncounterPhase";
 
 type PhaseInterceptorPhase = PhaseClass | PhaseString;
 
@@ -187,12 +190,16 @@ export default class PhaseInterceptor {
 
   /**
    * List of phases with their corresponding start methods.
+   *
+   * CAUTION: If a phase and its subclasses (if any) both appear in this list,
+   * make sure that this list contains said phase AFTER all of its subclasses.
+   * This way, the phase's `prototype.start` is properly preserved during
+   * `initPhases()` so that its subclasses can use `super.start()` properly.
    */
   private PHASES = [
     [ LoginPhase, this.startPhase ],
     [ TitlePhase, this.startPhase ],
     [ SelectGenderPhase, this.startPhase ],
-    [ EncounterPhase, this.startPhase ],
     [ NewBiomeEncounterPhase, this.startPhase ],
     [ SelectStarterPhase, this.startPhase ],
     [ PostSummonPhase, this.startPhase ],
@@ -227,6 +234,7 @@ export default class PhaseInterceptor {
     [ SwitchPhase, this.startPhase ],
     [ SwitchSummonPhase, this.startPhase ],
     [ PartyHealPhase, this.startPhase ],
+    [ FormChangePhase, this.startPhase ],
     [ EvolutionPhase, this.startPhase ],
     [ EndEvolutionPhase, this.startPhase ],
     [ LevelCapPhase, this.startPhase ],
@@ -240,6 +248,7 @@ export default class PhaseInterceptor {
     [ ModifierRewardPhase, this.startPhase ],
     [ PartyExpPhase, this.startPhase ],
     [ ExpPhase, this.startPhase ],
+    [ EncounterPhase, this.startPhase ],
   ];
 
   private endBySetMode = [