refactor: replace FavoritesContext with zustand store

__tests__/detail/screens/DetailScreen.test.tsx

@@ -1,6 +1,5 @@
 import { render, screen } from "@testing-library/react-native";
 import { DetailScreen } from "@/src/detail";
-import { FavoritesProvider } from "@/src/shared";
 import type { Pokemon } from "@/src/shared";
 
 const mockPokemon: Pokemon = {
@@ -43,12 +42,7 @@ jest.mock("@/src/detail/hooks/usePokemonSpeciesInfo", () => ({
   usePokemonSpeciesInfo: () => mockUsePokemonSpeciesInfo,
 }));
 
-const renderWithProvider = (id: string) =>
-  render(
-    <FavoritesProvider>
-      <DetailScreen id={id} />
-    </FavoritesProvider>,
-  );
+const renderWithProvider = (id: string) => render(<DetailScreen id={id} />);
 
 describe("DetailScreen", () => {
   beforeEach(() => {

__tests__/favorites/screens/FavoritesScreen.test.tsx

@@ -1,6 +1,5 @@
 import { render, screen } from "@testing-library/react-native";
 import { FavoritesScreen } from "@/src/favorites";
-import { FavoritesProvider } from "@/src/shared";
 import type { PokemonSummary } from "@/src/shared";
 
 const mockUsePokemonByIds = {
@@ -27,12 +26,7 @@ jest.mock("expo-router", () => ({
   },
 }));
 
-const renderWithProvider = () =>
-  render(
-    <FavoritesProvider>
-      <FavoritesScreen />
-    </FavoritesProvider>,
-  );
+const renderWithProvider = () => render(<FavoritesScreen />);
 
 describe("FavoritesScreen", () => {
   beforeEach(() => {

__tests__/home/screens/HomeScreen.test.tsx

@@ -1,6 +1,5 @@
 import { render, screen, fireEvent } from "@testing-library/react-native";
 import { HomeScreen } from "@/src/home";
-import { FavoritesProvider } from "@/src/shared";
 import type { PokemonSummary } from "@/src/shared";
 
 const mockPokemon: PokemonSummary[] = [
@@ -42,12 +41,7 @@ jest.mock("expo-router", () => ({
   },
 }));
 
-const renderWithProvider = () =>
-  render(
-    <FavoritesProvider>
-      <HomeScreen />
-    </FavoritesProvider>,
-  );
+const renderWithProvider = () => render(<HomeScreen />);
 
 describe("HomeScreen", () => {
   beforeEach(() => {

__tests__/shared/contexts/FavoritesContext.test.tsx → __tests__/shared/stores/useFavoritesStore.test.tsx

@@ -1,6 +1,7 @@
 import { renderHook, act } from "@testing-library/react-native";
 import { Alert } from "react-native";
-import { FavoritesProvider, useFavorites } from "@/src/shared";
+import { useFavorites } from "@/src/shared";
+import { useFavoritesStore } from "@/src/shared/stores/useFavoritesStore";
 
 jest.mock("@/src/shared/i18n", () => ({
   i18n: {
@@ -10,31 +11,28 @@ jest.mock("@/src/shared/i18n", () => ({
 
 jest.spyOn(Alert, "alert").mockImplementation(() => {});
 
-describe("FavoritesContext", () => {
-  const wrapper = ({ children }: { children: React.ReactNode }) => (
-    <FavoritesProvider>{children}</FavoritesProvider>
-  );
-
+describe("useFavoritesStore", () => {
   beforeEach(() => {
+    useFavoritesStore.setState({ favoriteIds: [] });
     (Alert.alert as jest.Mock).mockClear();
   });
 
   describe("useFavorites", () => {
     it("初期状態ではお気に入りが空である", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       expect(result.current.favoriteIds).toEqual([]);
     });
 
     it("toggleFavoriteでポケモンをお気に入りに追加できる", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       act(() => {
         result.current.toggleFavorite(25);
       });
       expect(result.current.favoriteIds).toEqual([25]);
     });
 
     it("toggleFavoriteで既にお気に入りのポケモンを削除できる", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       act(() => {
         result.current.toggleFavorite(25);
       });
@@ -45,20 +43,20 @@ describe("FavoritesContext", () => {
     });
 
     it("isFavoriteがお気に入り登録済みのポケモンに対してtrueを返す", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       act(() => {
         result.current.toggleFavorite(25);
       });
       expect(result.current.isFavorite(25)).toBe(true);
     });
 
     it("isFavoriteが未登録のポケモンに対してfalseを返す", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       expect(result.current.isFavorite(25)).toBe(false);
     });
 
     it("お気に入りが6匹に達している場合、追加できずアラートが表示される", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       act(() => {
         result.current.toggleFavorite(1);
         result.current.toggleFavorite(2);
@@ -81,7 +79,7 @@ describe("FavoritesContext", () => {
     });
 
     it("上限に達していても既存のお気に入りは削除できる", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       act(() => {
         result.current.toggleFavorite(1);
         result.current.toggleFavorite(2);
@@ -99,7 +97,7 @@ describe("FavoritesContext", () => {
     });
 
     it("isFullが上限到達時にtrueを返す", () => {
-      const { result } = renderHook(() => useFavorites(), { wrapper });
+      const { result } = renderHook(() => useFavorites());
       expect(result.current.isFull).toBe(false);
 
       act(() => {
@@ -112,13 +110,5 @@ describe("FavoritesContext", () => {
       });
       expect(result.current.isFull).toBe(true);
     });
-
-    it("Provider外でuseFavoritesを呼ぶとエラーになる", () => {
-      jest.spyOn(console, "error").mockImplementation(() => {});
-      expect(() => {
-        renderHook(() => useFavorites());
-      }).toThrow("useFavorites must be used within a FavoritesProvider");
-      jest.restoreAllMocks();
-    });
   });
 });

app/_layout.tsx

@@ -2,7 +2,7 @@ import { useEffect } from "react";
 import { Stack } from "expo-router";
 import { I18nextProvider, useTranslation } from "react-i18next";
 import * as SplashScreen from "expo-splash-screen";
-import { FavoritesProvider, i18n, initI18n } from "@/src/shared";
+import { i18n, initI18n } from "@/src/shared";
 import { AnimatedSplash } from "@/src/splash";
 
 SplashScreen.preventAutoHideAsync();
@@ -25,11 +25,9 @@ function RootLayoutNav() {
 export default function RootLayout() {
   return (
     <I18nextProvider i18n={i18n}>
-      <FavoritesProvider>
-        <AnimatedSplash>
-          <RootLayoutNav />
-        </AnimatedSplash>
-      </FavoritesProvider>
+      <AnimatedSplash>
+        <RootLayoutNav />
+      </AnimatedSplash>
     </I18nextProvider>
   );
 }

package.json

@@ -39,7 +39,8 @@
     "react-native-safe-area-context": "~5.6.0",
     "react-native-screens": "~4.23.0",
     "react-native-web": "~0.21.0",
-    "react-native-worklets": "0.7.4"
+    "react-native-worklets": "0.7.4",
+    "zustand": "^5.0.12"
   },
   "expo": {
     "install": {

src/shared/index.ts

@@ -1,7 +1,7 @@
 export { i18n, initI18n, SUPPORTED_LANGUAGES, STORAGE_KEY } from "./i18n";
 export type { SupportedLanguage } from "./i18n";
 export { useLanguage } from "./i18n";
-export { FavoritesProvider, useFavorites } from "./contexts/FavoritesContext";
+export { useFavorites, useFavoritesStore } from "./stores/useFavoritesStore";
 export { PokemonCard } from "./components/PokemonCard";
 export { FavoriteButton } from "./components/FavoriteButton";
 export { typeColors } from "./domain/typeColors";

src/shared/stores/useFavoritesStore.ts

@@ -0,0 +1,42 @@
+import { create } from "zustand";
+import { Alert } from "react-native";
+import { i18n } from "../i18n";
+
+const MAX_FAVORITES = 6;
+
+interface FavoritesStoreState {
+  favoriteIds: number[];
+  toggleFavorite: (id: number) => void;
+}
+
+interface FavoritesValue extends FavoritesStoreState {
+  isFavorite: (id: number) => boolean;
+  isFull: boolean;
+}
+
+export const useFavoritesStore = create<FavoritesStoreState>((set, get) => ({
+  favoriteIds: [],
+
+  toggleFavorite: (id: number) => {
+    const { favoriteIds } = get();
+    if (favoriteIds.includes(id)) {
+      set({ favoriteIds: favoriteIds.filter((fid) => fid !== id) });
+      return;
+    }
+    if (favoriteIds.length >= MAX_FAVORITES) {
+      Alert.alert(i18n.t("favorites.limitTitle"), i18n.t("favorites.limitMessage"));
+      return;
+    }
+    set({ favoriteIds: [...favoriteIds, id] });
+  },
+}));
+
+export function useFavorites(): FavoritesValue {
+  const { favoriteIds, toggleFavorite } = useFavoritesStore();
+  return {
+    favoriteIds,
+    toggleFavorite,
+    isFavorite: (id: number) => favoriteIds.includes(id),
+    isFull: favoriteIds.length >= MAX_FAVORITES,
+  };
+}