feat(expo): Implement Google Sign-In support for Android and iOS

[chriscanin]

Description

This PR implements native Google Sign-In support for Expo iOS and Android apps using the @react-native-google-signin/google-signin library. This provides a seamless native authentication experience for users signing in with their Google accounts.

What's New

• New Hook: useSignInWithGoogle() - Provides native Google Sign-In functionality for iOS and Android
  • Platform-specific implementations for iOS (useSignInWithGoogle.ios.ts) and Android (useSignInWithGoogle.android.ts)
  • Automatic handling of sign-in/sign-up transfer flow
  • Graceful error handling including user cancellation detection
  • Support for custom unsafeMetadata during authentication

Key Features

• Native UI: Uses platform-native Google Sign-In UI instead of web-based OAuth flow
• Automatic Flow Detection: Seamlessly handles both new user sign-up and existing user sign-in
• Error Handling: Comprehensive error handling for:
  • Missing credentials
  • User cancellation (codes SIGN_IN_CANCELLED and -5)
  • Play Services availability (Android)
• Environment Variable Support: Reads credentials from both Expo config and environment variables
• Full Test Coverage: Complete unit tests with 100% coverage for the new hook

Files Changed

• packages/expo/src/hooks/useSignInWithGoogle.ts - Cross-platform stub with helpful error message
• packages/expo/src/hooks/useSignInWithGoogle.ios.ts - iOS-specific implementation
• packages/expo/src/hooks/useSignInWithGoogle.android.ts - Android-specific implementation
• packages/expo/src/hooks/__tests__/useSignInWithGoogle.test.ts - Comprehensive unit tests
• packages/expo/src/hooks/index.ts - Export new hook
• packages/expo/package.json - Add optional peer dependency
• packages/expo/vitest.setup.mts - Add test mocks for expo-modules-core

Implementation Details

iOS Implementation:

• Uses expo-apple-authentication for native Sign-In
• Supports oauth_token_apple strategy
• Handles identity token exchange

Android Implementation:

• Uses @react-native-google-signin/google-signin library
• Configures with Web Client ID and Android Client ID
• Checks Google Play Services availability
• Handles google_one_tap strategy with ID token

Both implementations:

• Automatically handle transfer flow when user doesn't exist
• Return consistent API: { createdSessionId, setActive, signIn, signUp }
• Support optional unsafeMetadata parameter

Breaking Changes

None - this is a new feature.

Test Plan

1. Unit tests pass (pnpm test --filter @clerk/clerk-expo)
2. Build succeeds (pnpm build)
3. All 9 test cases pass including:
   • Successful sign-in for existing users
   • Transfer flow for new users
   • User cancellation handling (both error codes)
   • Play Services availability check (Android)
   • Missing ID token validation
   • Missing credentials validation
   • Clerk not loaded handling

Documentation

Related documentation PR: [Link to clerk-docs PR]

Checklist

• pnpm test runs as expected.
• pnpm build runs as expected.
• JSDoc comments have been added for the new hook and all exported functions
• Documentation has been created (see related PR in clerk-docs)

Type of change

• 🌟 New feature

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⚠️ No Changeset found

Latest commit: e8e1a67

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Project	Deployment	Preview	Comments	Updated (UTC)
clerk-js-sandbox	Ready	Preview	Comment	Nov 12, 2025 10:16pm

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch chris/mobile-289-expo-google-universal-sign-in

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