전역 구조 리팩터링 및 테스트 확장

lib/core/services/token_storage.dart

@@ -0,0 +1,19 @@
+import 'token_storage_stub.dart'
+    if (dart.library.html) 'token_storage_web.dart'
+    if (dart.library.io) 'token_storage_native.dart';
+
+/// 액세스/리프레시 토큰을 안전하게 보관하는 스토리지 인터페이스.
+abstract class TokenStorage {
+  Future<void> writeAccessToken(String? token);
+
+  Future<String?> readAccessToken();
+
+  Future<void> writeRefreshToken(String? token);
+
+  Future<String?> readRefreshToken();
+
+  Future<void> clear();
+}
+
+/// 플랫폼에 맞는 스토리지 구현체를 생성한다.
+TokenStorage createTokenStorage() => buildTokenStorage();

lib/core/services/token_storage_native.dart

@@ -0,0 +1,53 @@
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+import 'token_storage.dart';
+
+const _kAccessTokenKey = 'access_token';
+const _kRefreshTokenKey = 'refresh_token';
+
+TokenStorage buildTokenStorage() {
+  const storage = FlutterSecureStorage(
+    aOptions: AndroidOptions(encryptedSharedPreferences: true),
+    iOptions: IOSOptions(accessibility: KeychainAccessibility.first_unlock),
+    mOptions: MacOsOptions(),
+    wOptions: WindowsOptions(),
+    lOptions: LinuxOptions(),
+  );
+  return _SecureTokenStorage(storage);
+}
+
+class _SecureTokenStorage implements TokenStorage {
+  const _SecureTokenStorage(this._storage);
+
+  final FlutterSecureStorage _storage;
+
+  @override
+  Future<void> clear() async {
+    await _storage.delete(key: _kAccessTokenKey);
+    await _storage.delete(key: _kRefreshTokenKey);
+  }
+
+  @override
+  Future<String?> readAccessToken() => _storage.read(key: _kAccessTokenKey);
+
+  @override
+  Future<String?> readRefreshToken() => _storage.read(key: _kRefreshTokenKey);
+
+  @override
+  Future<void> writeAccessToken(String? token) async {
+    if (token == null || token.isEmpty) {
+      await _storage.delete(key: _kAccessTokenKey);
+      return;
+    }
+    await _storage.write(key: _kAccessTokenKey, value: token);
+  }
+
+  @override
+  Future<void> writeRefreshToken(String? token) async {
+    if (token == null || token.isEmpty) {
+      await _storage.delete(key: _kRefreshTokenKey);
+      return;
+    }
+    await _storage.write(key: _kRefreshTokenKey, value: token);
+  }
+}

lib/core/services/token_storage_stub.dart

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+import 'token_storage.dart';
+
+TokenStorage buildTokenStorage() => _UnsupportedTokenStorage();
+
+class _UnsupportedTokenStorage implements TokenStorage {
+  Never _unsupported() {
+    throw UnsupportedError('TokenStorage is not supported on this platform.');
+  }
+
+  @override
+  Future<void> clear() async => _unsupported();
+
+  @override
+  Future<String?> readAccessToken() async => _unsupported();
+
+  @override
+  Future<String?> readRefreshToken() async => _unsupported();
+
+  @override
+  Future<void> writeAccessToken(String? token) async => _unsupported();
+
+  @override
+  Future<void> writeRefreshToken(String? token) async => _unsupported();
+}

lib/core/services/token_storage_web.dart

@@ -0,0 +1,45 @@
+// ignore: deprecated_member_use, avoid_web_libraries_in_flutter
+import 'dart:html' as html;
+
+import 'token_storage.dart';
+
+const _kAccessTokenKey = 'access_token';
+const _kRefreshTokenKey = 'refresh_token';
+
+TokenStorage buildTokenStorage() => _WebTokenStorage(html.window.localStorage);
+
+class _WebTokenStorage implements TokenStorage {
+  const _WebTokenStorage(this._storage);
+
+  final Map<String, String> _storage;
+
+  @override
+  Future<void> clear() async {
+    _storage.remove(_kAccessTokenKey);
+    _storage.remove(_kRefreshTokenKey);
+  }
+
+  @override
+  Future<String?> readAccessToken() async => _storage[_kAccessTokenKey];
+
+  @override
+  Future<String?> readRefreshToken() async => _storage[_kRefreshTokenKey];
+
+  @override
+  Future<void> writeAccessToken(String? token) async {
+    if (token == null || token.isEmpty) {
+      _storage.remove(_kAccessTokenKey);
+    } else {
+      _storage[_kAccessTokenKey] = token;
+    }
+  }
+
+  @override
+  Future<void> writeRefreshToken(String? token) async {
+    if (token == null || token.isEmpty) {
+      _storage.remove(_kRefreshTokenKey);
+    } else {
+      _storage[_kRefreshTokenKey] = token;
+    }
+  }
+}