feat: i18n 개선 및 userfront 로그인/로케일 보완

userfront/test/helpers/web_storage.dart

@@ -0,0 +1,5 @@
+import 'web_storage_stub.dart'
+    if (dart.library.html) 'web_storage_web.dart';
+
+export 'web_storage_stub.dart'
+    if (dart.library.html) 'web_storage_web.dart';

userfront/test/helpers/web_storage_stub.dart

@@ -0,0 +1,21 @@
+class WebStorage {
+  bool get isWeb => false;
+
+  String? get(String key) => null;
+
+  void set(String key, String value) {}
+
+  String? getSession(String key) => null;
+
+  void setSession(String key, String value) {}
+
+  void removeSession(String key) {}
+
+  void clearSession() {}
+
+  void remove(String key) {}
+
+  void clear() {}
+}
+
+final webStorage = WebStorage();

userfront/test/helpers/web_storage_web.dart

@@ -0,0 +1,37 @@
+// ignore_for_file: avoid_web_libraries_in_flutter
+
+import 'dart:html' as html;
+
+class WebStorage {
+  bool get isWeb => true;
+
+  String? get(String key) => html.window.localStorage[key];
+
+  void set(String key, String value) {
+    html.window.localStorage[key] = value;
+  }
+
+  String? getSession(String key) => html.window.sessionStorage[key];
+
+  void setSession(String key, String value) {
+    html.window.sessionStorage[key] = value;
+  }
+
+  void removeSession(String key) {
+    html.window.sessionStorage.remove(key);
+  }
+
+  void clearSession() {
+    html.window.sessionStorage.clear();
+  }
+
+  void remove(String key) {
+    html.window.localStorage.remove(key);
+  }
+
+  void clear() {
+    html.window.localStorage.clear();
+  }
+}
+
+final webStorage = WebStorage();

userfront/test/locale_storage_web_test.dart

@@ -0,0 +1,88 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:userfront/core/i18n/locale_storage.dart';
+import 'package:userfront/core/i18n/locale_storage_web.dart' as locale_web;
+
+import 'helpers/web_storage.dart';
+
+void main() {
+  setUp(() {
+    locale_web.LocaleStorageImpl.forceMemoryStorageForTests(false);
+    locale_web.LocaleStorageImpl.forceSessionStorageForTests(false);
+    if (webStorage.isWeb) {
+      webStorage.clear();
+      webStorage.clearSession();
+    }
+  });
+
+  tearDown(() {
+    locale_web.LocaleStorageImpl.forceMemoryStorageForTests(false);
+    locale_web.LocaleStorageImpl.forceSessionStorageForTests(false);
+    if (webStorage.isWeb) {
+      webStorage.clear();
+      webStorage.clearSession();
+    }
+  });
+
+  test(
+    'localStorage write/read (웹)',
+    () {
+      if (!webStorage.isWeb) {
+        return;
+      }
+
+      LocaleStorage.write('ko');
+      expect(webStorage.get('locale'), 'ko');
+      expect(LocaleStorage.read(), 'ko');
+    },
+    skip: !webStorage.isWeb,
+  );
+
+  test(
+    'legacy key에서 locale로 마이그레이션 (웹)',
+    () {
+      if (!webStorage.isWeb) {
+        return;
+      }
+
+      webStorage.set('baron_locale', 'en');
+      expect(LocaleStorage.read(), 'en');
+      expect(webStorage.get('locale'), 'en');
+      expect(webStorage.get('baron_locale'), isNull);
+    },
+    skip: !webStorage.isWeb,
+  );
+
+  test(
+    'localStorage 접근이 차단되면 메모리 fallback (웹)',
+    () {
+      if (!webStorage.isWeb) {
+        return;
+      }
+
+      locale_web.LocaleStorageImpl.forceMemoryStorageForTests(true);
+
+      LocaleStorage.write('en');
+      expect(webStorage.get('locale'), isNull);
+      expect(webStorage.getSession('locale'), isNull);
+      expect(LocaleStorage.read(), 'en');
+    },
+    skip: !webStorage.isWeb,
+  );
+
+  test(
+    'localStorage 접근이 차단되면 sessionStorage로 fallback (웹)',
+    () {
+      if (!webStorage.isWeb) {
+        return;
+      }
+
+      locale_web.LocaleStorageImpl.forceSessionStorageForTests(true);
+
+      LocaleStorage.write('ko');
+      expect(webStorage.get('locale'), isNull);
+      expect(webStorage.getSession('locale'), 'ko');
+      expect(LocaleStorage.read(), 'ko');
+    },
+    skip: !webStorage.isWeb,
+  );
+}

userfront/test/locale_utils_test.dart

@@ -0,0 +1,66 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:userfront/core/i18n/locale_utils.dart';
+
+void main() {
+  group('locale_utils', () {
+    test('normalizeLocaleCode handles supported locales', () {
+      expect(normalizeLocaleCode('ko'), 'ko');
+      expect(normalizeLocaleCode('ko-KR'), 'ko');
+      expect(normalizeLocaleCode('en'), 'en');
+      expect(normalizeLocaleCode('en-US'), 'en');
+    });
+
+    test('normalizeLocaleCode falls back to default', () {
+      expect(normalizeLocaleCode('ja'), defaultLocaleCode);
+      expect(normalizeLocaleCode(null), defaultLocaleCode);
+      expect(normalizeLocaleCode(''), defaultLocaleCode);
+    });
+
+    test('extractLocaleFromPath picks locale when present', () {
+      expect(extractLocaleFromPath(Uri.parse('/ko/signin')), 'ko');
+      expect(extractLocaleFromPath(Uri.parse('/en/profile')), 'en');
+      expect(extractLocaleFromPath(Uri.parse('/ko')), 'ko');
+    });
+
+    test('extractLocaleFromPath returns null when missing', () {
+      expect(extractLocaleFromPath(Uri.parse('/signin')), isNull);
+      expect(extractLocaleFromPath(Uri.parse('/zz/signin')), isNull);
+    });
+
+    test('stripLocalePath removes locale segment', () {
+      expect(stripLocalePath(Uri.parse('/ko/signin')), '/signin');
+      expect(stripLocalePath(Uri.parse('/en/profile')), '/profile');
+      expect(stripLocalePath(Uri.parse('/ko')), '/');
+      expect(stripLocalePath(Uri.parse('/en/')), '/');
+    });
+
+    test('stripLocalePath keeps path without locale', () {
+      expect(stripLocalePath(Uri.parse('/signin')), '/signin');
+      expect(stripLocalePath(Uri.parse('/auth/callback')), '/auth/callback');
+    });
+
+    test('buildLocalizedPath applies locale', () {
+      expect(buildLocalizedPath('ko', Uri.parse('/signin')), '/ko/signin');
+      expect(buildLocalizedPath('en', Uri.parse('/signin')), '/en/signin');
+      expect(buildLocalizedPath('ko', Uri.parse('/')), '/ko');
+      expect(buildLocalizedPath('en', Uri.parse('/')), '/en');
+    });
+
+    test('buildLocalizedPath preserves query parameters', () {
+      final uri = Uri.parse('/signin?redirect_uri=https://example.com');
+      expect(
+        buildLocalizedPath('ko', uri),
+        '/ko/signin?redirect_uri=https%3A%2F%2Fexample.com',
+      );
+    });
+
+    test('buildLocalizedPath replaces existing locale', () {
+      expect(buildLocalizedPath('en', Uri.parse('/ko/signin')), '/en/signin');
+      expect(buildLocalizedPath('ko', Uri.parse('/en/profile')), '/ko/profile');
+    });
+
+    test('buildLocalizedPath drops unknown 2-letter prefix', () {
+      expect(buildLocalizedPath('ko', Uri.parse('/zz/signin')), '/ko/signin');
+    });
+  });
+}

userfront/test/widget_test.dart

@@ -5,15 +5,36 @@
 // gestures. You can also use WidgetTester to find child widgets in the widget
 // tree, read text, and verify that the values of widget properties are correct.
 
+import 'dart:ui';
+
+import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import 'package:userfront/main.dart' show BaronSSOApp;
 
+class _TestAssetLoader extends AssetLoader {
+  const _TestAssetLoader();
+
+  @override
+  Future<Map<String, dynamic>> load(String path, Locale locale) async {
+    return {};
+  }
+}
+
 void main() {
   testWidgets('BaronSSOApp builds', (WidgetTester tester) async {
     // runApp에서 ProviderScope로 감싸서 쓰고 있으니 테스트도 동일하게 감쌈
-    await tester.pumpWidget(const ProviderScope(child: BaronSSOApp()));
+    await tester.pumpWidget(
+      EasyLocalization(
+        supportedLocales: const [Locale('en'), Locale('ko')],
+        fallbackLocale: const Locale('en'),
+        startLocale: const Locale('en'),
+        path: 'assets/translations',
+        assetLoader: const _TestAssetLoader(),
+        child: const ProviderScope(child: BaronSSOApp()),
+      ),
+    );
     await tester.pump(); // 한 프레임 더
   });
 }