Mobile App Testing (React Native + Expo)

This skill enables comprehensive testing and debugging of React Native mobile applications built with Expo for iOS and Android platforms.

When to Use This Skill

Use this skill when you need to:

• Start and test the Expo development server
• Verify mobile app functionality on iOS/Android simulators or physical devices
• Debug React Native UI behavior and interactions
• Test mobile-specific features (biometrics, camera, QR scanning)
• Validate Bitcoin wallet operations and transactions
• Check navigation flows and screen transitions
• Test authentication flows (PIN, biometric, auto-lock)
• Verify wallet creation, import, and management features

Prerequisites

• Node.js 18.17+ (Node 20 recommended) installed on the system
• npm or bun package manager
• Expo CLI (installed automatically with dependencies)
• For iOS testing: macOS with Xcode 15+
• For Android testing: Android Studio with SDK 34+
• For device testing: Expo Go app or configured simulator/emulator
• Firebase configuration files (google-services.json for Android, GoogleService-Info.plist for iOS)

Core Capabilities

1. Development Server Management

• Start Metro bundler with npm start
• Run on iOS simulator with npm run ios
• Run on Android emulator with npm run android
• Start with tunnel for physical devices with npm run start-tunnel
• Clear cache and restart with npx expo start -c

2. Mobile App Testing

• Test wallet creation and import flows
• Verify Bitcoin send/receive transactions
• Test QR code scanning functionality
• Validate biometric authentication (Face ID, Touch ID)
• Test PIN setup and verification
• Verify auto-lock functionality
• Test multi-wallet management
• Validate fee bumping (RBF/CPFP)
• Test coin control and UTXO selection

3. Debugging & Troubleshooting

• View Metro bundler logs
• Inspect React Native error boundaries
• Test Firebase Crashlytics integration
• Debug iOS/Android specific issues
• Clear build caches
• Reinstall dependencies and pods

Usage Examples

Example 1: Start Development Server

# Start Metro bundler
npm start

# Or with cache clear for troubleshooting
npx expo start -c

Example 2: Run on iOS Simulator

# Run the app on iOS simulator
npm run ios

# Or with debug mode
npm run ios-debug

Example 3: Run on Android Emulator

# Run the app on Android emulator
npm run android

# Or clean build
cd android && ./gradlew clean && cd .. && npm run android

Example 4: Test on Physical Device with Tunnel

# Start with tunnel mode for physical device testing
npm run start-tunnel
# Scan QR code with Expo Go app

Example 5: Test Specific Features

# Test Firebase Crashlytics
node scripts/test-crashlytics-simple.js

# Test biometric authentication
node scripts/test-biometric.js

# Test Firebase connectivity
node scripts/test-firebase-connectivity.js

Guidelines

1. Always start fresh - Clear cache with npx expo start -c when encountering unexpected behavior
2. Test on both platforms - iOS and Android may behave differently for native features
3. Use physical devices for native features - Biometrics, camera, and other hardware features require real devices
4. Check Firebase configuration - Ensure google-services.json and GoogleService-Info.plist are properly configured
5. Monitor Metro bundler output - Watch for errors and warnings during development
6. Test with small Bitcoin amounts - Always test wallet functionality with minimal funds first
7. Verify security features - Test PIN, biometric auth, and auto-lock on actual devices
8. Test offline scenarios - Verify app behavior when network is unavailable
9. Use manual test scripts - Run scripts in /scripts directory for specific feature validation

Common Patterns

Pattern: Troubleshoot Metro Bundler Issues

# Clear Metro cache and restart
npx expo start -c

Pattern: Fix iOS Build Issues

# Reinstall CocoaPods dependencies
cd ios && pod deintegrate && pod install && cd ..

Pattern: Fix Android Build Issues

# Clean Gradle build
cd android && ./gradlew clean && cd ..

Pattern: Test Wallet Creation Flow

# Start app and manually test:
# 1. Launch app
# 2. Tap "Create New Wallet"
# 3. Set PIN
# 4. Backup recovery phrase
# 5. Verify wallet appears on home screen

Pattern: Test Bitcoin Transaction

# Start app and manually test:
# 1. Navigate to Send screen
# 2. Scan or paste recipient address
# 3. Enter amount
# 4. Select fee level
# 5. Review and confirm transaction
# 6. Verify transaction appears in history

Pattern: Test Authentication

# Start app and manually test:
# 1. Enable auto-lock in settings
# 2. Lock app or wait for timeout
# 3. Reopen app
# 4. Verify PIN/biometric prompt appears
# 5. Authenticate and verify access granted

Pattern: Run Manual Test Scripts

# Test Firebase integration
node scripts/test-firebase-connectivity.js

# Test crashlytics reporting
node scripts/test-crashlytics-simple.js

# Test biometric setup
node scripts/test-biometric.js

Testing Key Features

Wallet Operations

• Create Wallet: Test BIP39 mnemonic generation and wallet creation
• Import Wallet: Test importing 12/15/18/21/24-word mnemonics
• Multi-Wallet: Test creating and switching between multiple wallets
• Backup & Recovery: Test recovery phrase backup and verification

Bitcoin Transactions

• Send: Test sending Bitcoin with different fee levels
• Receive: Test generating and displaying receive addresses
• Transaction History: Test viewing transaction details and status
• Fee Bumping: Test RBF and CPFP fee bumping for stuck transactions

Security & Authentication

• PIN Setup: Test PIN creation and verification
• Biometric Auth: Test Face ID/Touch ID setup and authentication
• Auto-Lock: Test auto-lock timeout and unlock flow
• Recovery Phrase: Test phrase backup and secure storage

Advanced Features

• Coin Control: Test manual UTXO selection
• XPUB Export: Test extended public key generation
• Address Management: Test viewing all wallet addresses
• Fee Settings: Test custom fee configuration

Limitations

• Requires native environment: Cannot test iOS features without macOS/Xcode
• Simulators have limitations: Some features (biometrics, camera) require physical devices
• Network dependent: Bitcoin operations require internet connectivity to Blockstream API
• Manual testing required: No automated E2E test framework currently configured
• Platform-specific issues: iOS and Android may have different behaviors for native modules
• Firebase required: App requires proper Firebase configuration to run
• No web support: This is a mobile-only app (iOS/Android), cannot run in browser