#167410: _initCalled completed twice

packages/google_sign_in/google_sign_in_web/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.1.1
+
+* Throws a more actionable error when init is called more than once
+* Updates minimum supported SDK version to Flutter 3.32/Dart 3.8.
+
 ## NEXT
 
 * Updates minimum supported SDK version to Flutter 3.32/Dart 3.8.

packages/google_sign_in/google_sign_in_web/example/integration_test/google_sign_in_web_test.dart

@@ -65,8 +65,36 @@ void main() {
       await plugin.init(
         const InitParameters(clientId: 'some-non-null-client-id'),
       );
+    });
+
+    testWidgets('throws if init is called twice', (_) async {
+      await plugin.init(
+        const InitParameters(clientId: 'some-non-null-client-id'),
+      );
+
+      // Calling init() a second time should throw state error
+      expect(
+        () => plugin.init(
+          const InitParameters(clientId: 'some-non-null-client-id'),
+        ),
+        throwsStateError,
+      );
+    });
+
+    testWidgets('throws if init is called twice synchronously', (_) async {
+      final Future<void> firstInit = plugin.init(
+        const InitParameters(clientId: 'some-non-null-client-id'),
+      );
+
+      // Calling init() a second time synchronously should throw state error
+      expect(
+        () => plugin.init(
+          const InitParameters(clientId: 'some-non-null-client-id'),
+        ),
+        throwsStateError,
+      );
 
-      expect(plugin.initialized, completes);
+      await firstInit;
     });
 
     testWidgets('asserts clientId is not null', (_) async {
@@ -85,35 +113,6 @@ void main() {
         );
       }, throwsAssertionError);
     });
-
-    testWidgets('must be called for most of the API to work', (_) async {
-      expect(() async {
-        await plugin.attemptLightweightAuthentication(
-          const AttemptLightweightAuthenticationParameters(),
-        );
-      }, throwsStateError);
-
-      expect(() async {
-        await plugin.clientAuthorizationTokensForScopes(
-          const ClientAuthorizationTokensForScopesParameters(
-            request: AuthorizationRequestDetails(
-              scopes: <String>[],
-              userId: null,
-              email: null,
-              promptIfUnauthorized: false,
-            ),
-          ),
-        );
-      }, throwsStateError);
-
-      expect(() async {
-        await plugin.signOut(const SignOutParams());
-      }, throwsStateError);
-
-      expect(() async {
-        await plugin.disconnect(const DisconnectParams());
-      }, throwsStateError);
-    });
   });
 
   group('support queries', () {

packages/google_sign_in/google_sign_in_web/lib/google_sign_in_web.dart

@@ -49,10 +49,14 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
     @visibleForTesting GisSdkClient? debugOverrideGisSdkClient,
     @visibleForTesting
     StreamController<AuthenticationEvent>? debugAuthenticationController,
-  }) : _gisSdkClient = debugOverrideGisSdkClient,
-       _authenticationController =
+  }) : _authenticationController =
            debugAuthenticationController ??
            StreamController<AuthenticationEvent>.broadcast() {
+    // Only set _gisSdkClient if debugOverrideGisSdkClient is provided
+    if (debugOverrideGisSdkClient != null) {
+      _gisSdkClient = debugOverrideGisSdkClient;
+    }
+
     autoDetectedClientId = web.document
         .querySelector(clientIdMetaSelector)
         ?.getAttribute(clientIdAttributeName);
@@ -68,51 +72,28 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
 
   // A future that completes when the JS loader is done.
   late Future<void> _jsSdkLoadedFuture;
-  // A future that completes when the `init` call is done.
-  Completer<void>? _initCalled;
+
+  /// A completer used to track whether [init] has finished.
+  final Completer<void> _initCalled = Completer<void>();
+
+  /// A boolean flag to track if [init] has been called.
+  ///
+  /// This is used to prevent race conditions when [init] is called multiple
+  /// times without awaiting.
+  bool _isInitCalled = false;
 
   // A StreamController to communicate status changes from the GisSdkClient.
   final StreamController<AuthenticationEvent> _authenticationController;
 
   // The instance of [GisSdkClient] backing the plugin.
-  GisSdkClient? _gisSdkClient;
-
-  // A convenience getter to avoid using ! when accessing _gisSdkClient, and
-  // providing a slightly better error message when it is Null.
-  GisSdkClient get _gisClient {
-    assert(
-      _gisSdkClient != null,
-      'GIS Client not initialized. '
-      'GoogleSignInPlugin::init() or GoogleSignInPlugin::initWithParams() '
-      'must be called before any other method in this plugin.',
-    );
-    return _gisSdkClient!;
-  }
-
-  // This method throws if init or initWithParams hasn't been called at some
-  // point in the past. It is used by the [initialized] getter to ensure that
-  // users can't await on a Future that will never resolve.
-  void _assertIsInitCalled() {
-    if (_initCalled == null) {
-      throw StateError(
-        'GoogleSignInPlugin::init() or GoogleSignInPlugin::initWithParams() '
-        'must be called before any other method in this plugin.',
-      );
-    }
-  }
+  // Using late final ensures it can only be set once and throws if accessed before initialization.
+  late final GisSdkClient _gisSdkClient;
 
   /// A future that resolves when the plugin is fully initialized.
   ///
   /// This ensures that the SDK has been loaded, and that the `init` method
   /// has finished running.
-  @visibleForTesting
-  Future<void> get initialized {
-    _assertIsInitCalled();
-    return Future.wait<void>(<Future<void>>[
-      _jsSdkLoadedFuture,
-      _initCalled!.future,
-    ]);
-  }
+  Future<void> get _initialized => _initCalled.future;
 
   /// Stores the client ID if it was set in a meta-tag of the page.
   @visibleForTesting
@@ -125,6 +106,14 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
 
   @override
   Future<void> init(InitParameters params) async {
+    // Throw if init() is called more than once
+    if (_isInitCalled) {
+      throw StateError(
+        'init() has already been called. Calling init() more than once results in undefined behavior.',
+      );
+    }
+    _isInitCalled = true;
+
     final String? appClientId = params.clientId ?? autoDetectedClientId;
     assert(
       appClientId != null,
@@ -138,27 +127,25 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
       'serverClientId is not supported on Web.',
     );
 
-    _initCalled = Completer<void>();
-
     await _jsSdkLoadedFuture;
 
-    _gisSdkClient ??= GisSdkClient(
+    _gisSdkClient = GisSdkClient(
       clientId: appClientId!,
       nonce: params.nonce,
       hostedDomain: params.hostedDomain,
       authenticationController: _authenticationController,
       loggingEnabled: kDebugMode,
     );
 
-    _initCalled!.complete(); // Signal that `init` is fully done.
+    _initCalled.complete();
   }
 
   @override
   Future<AuthenticationResults?>? attemptLightweightAuthentication(
     AttemptLightweightAuthenticationParameters params,
   ) {
-    initialized.then((void value) {
-      _gisClient.requestOneTap();
+    _initialized.then((void value) {
+      _gisSdkClient.requestOneTap();
     });
     // One tap does not necessarily return immediately, and may never return,
     // so clients should not await it. Return null to signal that.
@@ -183,26 +170,26 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
 
   @override
   Future<void> signOut(SignOutParams params) async {
-    await initialized;
+    await _initialized;
 
-    await _gisClient.signOut();
+    await _gisSdkClient.signOut();
   }
 
   @override
   Future<void> disconnect(DisconnectParams params) async {
-    await initialized;
+    await _initialized;
 
-    await _gisClient.disconnect();
+    await _gisSdkClient.disconnect();
   }
 
   @override
   Future<ClientAuthorizationTokenData?> clientAuthorizationTokensForScopes(
     ClientAuthorizationTokensForScopesParameters params,
   ) async {
-    await initialized;
+    await _initialized;
     _validateScopes(params.request.scopes);
 
-    final String? token = await _gisClient.requestScopes(
+    final String? token = await _gisSdkClient.requestScopes(
       params.request.scopes,
       promptIfUnauthorized: params.request.promptIfUnauthorized,
       userHint: params.request.userId,
@@ -216,7 +203,7 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
   Future<ServerAuthorizationTokenData?> serverAuthorizationTokensForScopes(
     ServerAuthorizationTokensForScopesParameters params,
   ) async {
-    await initialized;
+    await _initialized;
     _validateScopes(params.request.scopes);
 
     // There is no way to know whether the flow will prompt in advance, so
@@ -225,7 +212,9 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
       return null;
     }
 
-    final String? code = await _gisClient.requestServerAuthCode(params.request);
+    final String? code = await _gisSdkClient.requestServerAuthCode(
+      params.request,
+    );
     return code == null
         ? null
         : ServerAuthorizationTokenData(serverAuthCode: code);
@@ -247,8 +236,8 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
   Future<void> clearAuthorizationToken(
     ClearAuthorizationTokenParams params,
   ) async {
-    await initialized;
-    return _gisClient.clearAuthorizationToken(params.accessToken);
+    await _initialized;
+    return _gisSdkClient.clearAuthorizationToken(params.accessToken);
   }
 
   @override
@@ -278,13 +267,13 @@ class GoogleSignInPlugin extends GoogleSignInPlatform {
         configuration ?? GSIButtonConfiguration();
     return FutureBuilder<void>(
       key: Key(config.hashCode.toString()),
-      future: initialized,
+      future: _initialized,
       builder: (BuildContext context, AsyncSnapshot<void> snapshot) {
         if (snapshot.hasData) {
           return FlexHtmlElementView(
             viewType: 'gsi_login_button',
             onElementCreated: (Object element) {
-              _gisClient.renderButton(element, config);
+              _gisSdkClient.renderButton(element, config);
             },
           );
         }

packages/google_sign_in/google_sign_in_web/pubspec.yaml

@@ -3,7 +3,7 @@ description: Flutter plugin for Google Sign-In, a secure authentication system
   for signing in with a Google account on Android, iOS and Web.
 repository: https://github.com/flutter/packages/tree/main/packages/google_sign_in/google_sign_in_web
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+google_sign_in%22
-version: 1.1.0
+version: 1.1.1
 
 environment:
   sdk: ^3.8.0