Port evolution, Rare Candy, evolution stones and vitamins

Pokémon that levelled up evolve after a won battle, following
EvolveAfterBattle's checks over the ROM's evolution bytes, with the
evolution screen that B can stop and move learning outside battle. The pack
uses Rare Candy, stones (with ABLE/NOT ABLE labels) and vitamins, and its
pocket tabs now sit in their own row.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/battle-world.test.ts

@@ -54,6 +54,46 @@ describe.skipIf(!existsSync(romPath))("world battle integration with the local R
     expect(world.save()).toEqual(saved);
   });
 
+  it("evolves a Pokémon that levelled up once the battle is won", () => {
+    const world = fixture();
+    const data = world.assets.pokemon;
+    const mon = generatePartyMon(data, {
+      species: 155, level: 13, item: 0, otId: world.playerId,
+      ot: "CHRIS", dvs: 0x823b, caughtData: 0,
+    });
+    mon.exp = data.expAtLevel(data.baseData(155).growthRate, 14) - 1;
+    world.state.party[0] = mon;
+    encounter(world);
+    const messages = finish(world);
+    expect(world.notice, world.diagnostic).toBe("");
+    expect(messages).toContain("What? CYNDAQUIL\nis evolving!");
+    expect(messages).toContain("evolved into\nQUILAVA!");
+    const evolved = world.state.party[0];
+    expect([evolved.species, evolved.nickname, evolved.level]).toEqual([156, "QUILAVA", 14]);
+    expect(evolved.stats).toEqual(calcStats(data, 156, evolved.dvs, 14, evolved.statExp));
+    expect(world.state.pokedex.caught.has(156)).toBe(true);
+    const saved = world.save();
+    world.restore(saved);
+    expect(world.save()).toEqual(saved);
+  });
+
+  it("considers only the Pokémon that levelled up (wEvolvableFlags)", () => {
+    const world = fixture();
+    const data = world.assets.pokemon;
+    // A level-14 Cyndaquil that does not take part could evolve, but
+    // EvolveAfterBattle only checks the one that grew to level 6.
+    world.state.party.push(generatePartyMon(data, {
+      species: 155, level: 14, item: 0, otId: world.playerId,
+      ot: "CHRIS", dvs: 0x823b, caughtData: 0,
+    }));
+    encounter(world);
+    const messages = finish(world);
+    expect(world.notice, world.diagnostic).toBe("");
+    expect(world.state.party[0].level).toBe(6);
+    expect(messages).not.toContain("evolving");
+    expect(world.state.party.map((mon) => mon.species)).toEqual([155, 155]);
+  });
+
   it("struggles with recoil once every move is out of PP", () => {
     const world = fixture();
     world.state.party[0].pp = [0, 0, 0, 0];

tests/foundation-browser.spec.ts

@@ -9,7 +9,10 @@ test.beforeEach(() =>
   test.skip(!existsSync(romPath), "Requires the local user ROM."),
 );
 
-async function start(page: Page, room: boolean | "poster" | "center" = false) {
+async function start(
+  page: Page,
+  room: boolean | "poster" | "center" | "candy" = false,
+) {
   await page.route("**/src/game/runtime.ts", async (route) => {
     const response = await route.fetch(),
       source = await response.text();
@@ -239,3 +242,37 @@ test("Start opens the start menu: SWITCH reorders the party and the pack tosses
   ]);
   expect(state.bag.items).toEqual([{ item: 18, quantity: 4 }]);
 });
+
+test("a Rare Candy levels up and evolves a Pokémon through the pack", async ({
+  page,
+}) => {
+  await start(page, "candy");
+  const text = page.locator("#dialogue-text"),
+    choices = page.locator("#dialogue-choice"),
+    pack = page.locator("#mart");
+  await page.keyboard.press("Enter");
+  await choices.getByRole("option", { name: /^PACK/ }).click();
+  await pack.getByRole("button", { name: /RARE CANDY/ }).click();
+  await choices.getByRole("option", { name: "USE", exact: true }).click();
+  await choices.getByRole("option", { name: /^CYNDAQUIL/ }).click();
+  await expect(text).toContainText("grew to");
+  await page.keyboard.press("KeyX");
+  await expect(text).toContainText("ATTACK");
+  await page.keyboard.press("KeyX");
+  await expect(text).toContainText("is evolving!");
+  await page.clock.runFor(1500);
+  await expect(page.locator("#pokepic")).toBeVisible();
+  await page.clock.runFor(8000);
+  await expect(text).toContainText("Congratulations!");
+  await page.keyboard.press("KeyX");
+  await expect(text).toContainText("QUILAVA!");
+  await page.keyboard.press("KeyX");
+  await expect(pack).toHaveAttribute("aria-label", "Pack");
+  await pack.getByRole("button", { name: "BACK", exact: true }).click();
+  await choices.getByRole("option", { name: /^EXIT/ }).click();
+  await page.clock.runFor(500);
+  await expect(page.locator("#game-notice")).toHaveText("");
+  const { state } = await backup(page);
+  expect([state.party[0].species, state.party[0].level]).toEqual([156, 14]);
+  expect(state.bag.items).toEqual([{ item: 18, quantity: 5 }]);
+});

tests/foundation-fixture.ts

@@ -4,10 +4,11 @@ import { OW } from "../src/game/world/constants";
 import { generatePartyMon } from "../src/game/party/pokemon";
 
 /** `room` places the player at the bedroom PC or poster, "center" at
- * Cherrygrove's Pokémon Center PC with two Pokémon; otherwise outdoors. */
+ * Cherrygrove's Pokémon Center PC with two Pokémon ("candy": the first at
+ * level 13, with a Rare Candy); otherwise outdoors. */
 export function foundationFixture(
   assets: CrystalAssets,
-  room: boolean | "poster" | "center",
+  room: boolean | "poster" | "center" | "candy",
 ) {
   const world = new GameWorld(
     assets,
@@ -16,11 +17,11 @@ export function foundationFixture(
   );
   world.state.scenes["24:4"] = 1;
   world.state.bag.keyItems.push(OW.BICYCLE);
-  if (room === "center") {
+  if (room === "center" || room === "candy") {
     world.state.party = [155, 16].map((species, i) =>
       generatePartyMon(assets.pokemon, {
         species,
-        level: 8 - i * 4,
+        level: room === "candy" && !i ? 13 : 8 - i * 4,
         item: 0,
         otId: world.playerId,
         ot: "CHRIS",
@@ -29,10 +30,11 @@ export function foundationFixture(
       }),
     );
     world.state.bag.items = [{ item: 18, quantity: 5 }]; // POTION
+    if (room === "candy") world.state.bag.items.push({ item: 0x20, quantity: 1 });
   }
   const save = world.save();
   const [map, x, y] =
-    room === "center"
+    room === "center" || room === "candy"
       ? ["26:5", 9, 2]
       : room === "poster"
         ? ["24:7", 6, 1]

tests/start-menu.test.ts

@@ -2,7 +2,7 @@ import { describe, expect, it } from "vitest";
 import { existsSync, readFileSync } from "node:fs";
 import { CrystalAssets } from "../src/game/rom/assets";
 import { GameWorld } from "../src/game/world/world";
-import { generatePartyMon, maxPP } from "../src/game/party/pokemon";
+import { calcStats, generatePartyMon, maxPP } from "../src/game/party/pokemon";
 import { ENGINE_FLAGS } from "../src/game/rom/profile";
 import { settle } from "./world-driver";
 
@@ -12,21 +12,30 @@ const romPath =
 const NEW_BARK_TOWN = "24:4",
   PLAYERS_HOUSE = "24:6",
   CYNDAQUIL = 155,
-  PIDGEY = 16;
+  QUILAVA = 156,
+  PIDGEY = 16,
+  PIKACHU = 25,
+  RAICHU = 26;
 const BICYCLE = 7,
   ANTIDOTE = 9,
   FULL_RESTORE = 0x0e,
   POTION = 0x12,
+  REPEL = 0x14,
+  THUNDERSTONE = 0x17,
+  HP_UP = 0x1a,
   RARE_CANDY = 0x20,
   REVIVE = 0x27,
   PP_UP = 0x3e,
   ETHER = 0x3f,
   ELIXER = 0x41,
+  EVERSTONE = 0x70,
   ENERGYPOWDER = 0x79,
   LEFTOVERS = 0x92,
   FLOWER_MAIL = 0x9e,
   BERRY = 0xad;
 const CUT = 0x0f,
+  GUST = 0x10,
+  SAND_ATTACK = 0x1c,
   TACKLE = 0x21,
   LEER = 0x2b,
   SMOKESCREEN = 0x6c;
@@ -520,7 +529,7 @@ describe.skipIf(!existsSync(romPath))("the start menu", () => {
     const world = fixture();
     world.state.bag.items.push(
       { item: BERRY, quantity: 1 },
-      { item: RARE_CANDY, quantity: 1 },
+      { item: REPEL, quantity: 1 },
     );
     world.state.bag.balls = [{ item: 5, quantity: 3 }];
     open(world);
@@ -529,11 +538,214 @@ describe.skipIf(!existsSync(romPath))("the start menu", () => {
     pickItem(world, 5);
     expect(menuItems(world)).toEqual(["GIVE", "TOSS", "QUIT"]);
     pick(world, "QUIT");
+    pickItem(world, REPEL);
+    pick(world, "USE");
+    expect(world.notice).toBe("Using REPEL is not ported yet.");
+    close(world);
+    expect(world.state.bag.items.find((slot) => slot.item === REPEL)).toBeTruthy();
+  });
+
+  it("raises a level with a Rare Candy, forgetting a move to learn a new one", () => {
+    const world = fixture();
+    const pidgey = world.state.party[1];
+    pidgey.moves = [TACKLE, CUT, LEER, GUST];
+    pidgey.pp = [35, 30, 30, 35];
+    pidgey.hp = 0;
+    world.state.bag.items.push({ item: RARE_CANDY, quantity: 2 });
+    const data = world.assets.pokemon;
+    open(world);
+    pick(world, "PACK");
     pickItem(world, RARE_CANDY);
     pick(world, "USE");
-    expect(world.notice).toBe("Using RARE CANDY is not ported yet.");
+    const pages = pick(world, "PIDGEY");
+    expect(pages.slice(0, 2)).toEqual([
+      "PIDGEY grew to level 5!",
+      pages[1],
+    ]);
+    expect(pages[1]).toMatch(/^ATTACK \d+ DEFENSE \d+ SPCL\.ATK \d+ SPCL\.DEF \d+ SPEED \d+$/);
+    expect(pages.slice(2)).toEqual([
+      "PIDGEY is trying to learn SAND-ATTACK.",
+      "But PIDGEY can't learn more than four moves.",
+      "Delete an older move to make room for SAND-ATTACK?",
+    ]);
+    world.choose(1);
+    expect(until(world)).toEqual(["Which move should be forgotten?"]);
+    expect(menuItems(world)).toEqual(["TACKLE", "CUT", "LEER", "GUST"]);
+    expect(pick(world, "CUT")).toEqual([
+      "HM moves can't be forgotten now.",
+      "Which move should be forgotten?",
+    ]);
+    expect(pick(world, "LEER")).toEqual([
+      "1, 2 and… Poof!",
+      "PIDGEY forgot LEER.",
+      "And…",
+      "PIDGEY learned SAND-ATTACK!",
+    ]);
     close(world);
-    expect(world.state.bag.items.find((slot) => slot.item === RARE_CANDY)).toBeTruthy();
+    const mon = world.state.party[1];
+    expect(mon.level).toBe(5);
+    expect(mon.exp).toBe(data.expAtLevel(data.baseData(PIDGEY).growthRate, 5));
+    expect(mon.moves).toEqual([TACKLE, CUT, SAND_ATTACK, GUST]);
+    expect(mon.pp[2]).toBe(data.move(SAND_ATTACK).pp);
+    // The Rare Candy adds the maximum HP's rise even to a fainted Pokémon.
+    expect(mon.hp).toBe(mon.stats[0] - pidgey.stats[0]);
+    expect(mon.hp).toBeGreaterThan(0);
+    expect(world.state.bag.items.at(-1)).toEqual({ item: RARE_CANDY, quantity: 1 });
+  });
+
+  it("can decline to learn the move", () => {
+    const world = fixture();
+    world.state.party[1].moves = [TACKLE, CUT, LEER, GUST];
+    world.state.bag.items.push({ item: RARE_CANDY, quantity: 1 });
+    open(world);
+    pick(world, "PACK");
+    pickItem(world, RARE_CANDY);
+    pick(world, "USE");
+    pick(world, "PIDGEY");
+    world.choose(0);
+    expect(until(world)).toEqual(["Stop learning SAND-ATTACK?"]);
+    world.choose(1);
+    expect(until(world)).toEqual(["PIDGEY did not learn SAND-ATTACK."]);
+    close(world);
+    expect(world.state.party[1].moves).toEqual([TACKLE, CUT, LEER, GUST]);
+    expect(world.state.party[1].level).toBe(5);
+  });
+
+  it("evolves after a Rare Candy, and B can stop it", () => {
+    for (const stop of [false, true]) {
+      const world = fixture();
+      const data = world.assets.pokemon;
+      world.state.party[0] = generatePartyMon(data, {
+        species: CYNDAQUIL,
+        level: 13,
+        item: 0,
+        otId: world.playerId,
+        ot: "CHRIS",
+        dvs: 0x9abc,
+        caughtData: 0,
+      });
+      world.state.bag.items.push({ item: RARE_CANDY, quantity: 1 });
+      open(world);
+      pick(world, "PACK");
+      pickItem(world, RARE_CANDY);
+      pick(world, "USE");
+      world.choose(0);
+      // Acknowledge pages until the evolution animation starts.
+      const pages: string[] = [];
+      for (let i = 0; i < 200 && !world.evolution; i++) {
+        const dialogue = world.dialogue;
+        if (dialogue) {
+          pages.push(dialogue.pages[dialogue.index].replace(/\n/g, " "));
+          if (dialogue.holdTicks !== undefined) world.tick();
+          else world.advanceDialogue();
+        } else world.tick();
+      }
+      expect(pages[0]).toBe("CYNDAQUIL grew to level 14!");
+      expect(pages.at(-1)).toBe("What? CYNDAQUIL is evolving!");
+      expect(world.picture).toBe(CYNDAQUIL);
+      // B does nothing before the flashes begin.
+      world.advanceDialogue();
+      expect(world.evolution).toBeDefined();
+      for (let tick = 0; tick < 40; tick++) world.tick();
+      if (stop) {
+        world.advanceDialogue();
+        expect(until(world)).toEqual(["Huh? CYNDAQUIL stopped evolving!"]);
+      } else {
+        expect(until(world)).toEqual([
+          "Congratulations! Your CYNDAQUIL",
+          "evolved into QUILAVA!",
+        ]);
+      }
+      close(world);
+      const mon = world.state.party[0];
+      expect(mon.level).toBe(14);
+      expect([mon.species, mon.nickname]).toEqual(
+        stop ? [CYNDAQUIL, "CYNDAQUIL"] : [QUILAVA, "QUILAVA"],
+      );
+      expect(mon.stats).toEqual(
+        calcStats(data, mon.species, mon.dvs, 14, mon.statExp),
+      );
+      expect(world.state.pokedex.caught.has(QUILAVA)).toBe(!stop);
+      expect(world.state.bag.items.some((slot) => slot.item === RARE_CANDY)).toBe(false);
+    }
+  });
+
+  it("evolves with a stone, which B cannot stop, unless held back by an Everstone", () => {
+    const world = fixture();
+    const data = world.assets.pokemon;
+    world.state.party[1] = generatePartyMon(data, {
+      species: PIKACHU,
+      level: 10,
+      item: EVERSTONE,
+      otId: world.playerId,
+      ot: "CHRIS",
+      dvs: 0x9abc,
+      caughtData: 0,
+    });
+    world.state.party[1].nickname = "SPARKY";
+    world.state.bag.items.push({ item: THUNDERSTONE, quantity: 2 });
+    open(world);
+    pick(world, "PACK");
+    pickItem(world, THUNDERSTONE);
+    expect(pick(world, "USE")).toEqual(["Use on which POKéMON?"]);
+    const party = world.dialogue?.choice;
+    expect(party?.kind === "menu" && party.details).toEqual(["NOT ABLE", "ABLE"]);
+    expect(pick(world, "CYNDAQUIL")).toEqual(["It won't have any effect."]);
+    pickItem(world, THUNDERSTONE);
+    pick(world, "USE");
+    expect(pick(world, "SPARKY")).toEqual(["It won't have any effect."]);
+    close(world);
+    world.state.party[1].item = 0;
+    open(world);
+    pick(world, "PACK");
+    pickItem(world, THUNDERSTONE);
+    pick(world, "USE");
+    world.choose(1);
+    for (let i = 0; i < 20 && !world.evolution; i++) {
+      if (world.dialogue?.holdTicks !== undefined) world.tick();
+      else world.advanceDialogue();
+    }
+    for (let tick = 0; tick < 60; tick++) world.tick();
+    world.advanceDialogue();
+    expect(until(world)).toEqual([
+      "Congratulations! Your SPARKY",
+      "evolved into RAICHU!",
+    ]);
+    close(world);
+    const mon = world.state.party[1];
+    // A nickname stays.
+    expect([mon.species, mon.nickname]).toEqual([RAICHU, "SPARKY"]);
+    expect(world.state.bag.items.at(-1)).toEqual({ item: THUNDERSTONE, quantity: 1 });
+  });
+
+  it("raises stat experience with a vitamin, up to its limit", () => {
+    const world = fixture();
+    const data = world.assets.pokemon;
+    const mon = world.state.party[0];
+    const hp = mon.hp,
+      happiness = mon.happiness;
+    world.state.bag.items.push({ item: HP_UP, quantity: 2 });
+    open(world);
+    pick(world, "PACK");
+    pickItem(world, HP_UP);
+    pick(world, "USE");
+    expect(pick(world, "CYNDAQUIL")).toEqual(["CYNDAQUIL's HEALTH rose."]);
+    close(world);
+    const raised = world.state.party[0];
+    expect(raised.statExp[0]).toBe(2560);
+    expect(raised.stats).toEqual(calcStats(data, CYNDAQUIL, raised.dvs, 8, raised.statExp));
+    expect(raised.hp).toBe(hp);
+    expect(raised.happiness).toBeGreaterThan(happiness);
+
+    raised.statExp[0] = 100 << 8;
+    open(world);
+    pick(world, "PACK");
+    pickItem(world, HP_UP);
+    pick(world, "USE");
+    expect(pick(world, "CYNDAQUIL")).toEqual(["It won't have any effect."]);
+    close(world);
+    expect(world.state.party[0].statExp[0]).toBe(100 << 8);
+    expect(world.state.bag.items.at(-1)).toEqual({ item: HP_UP, quantity: 1 });
   });
 
   it("saves the state from before the menu while it is open", () => {