# Service Fallback & Graceful Degradation Tests

Tests EU-Utility's ability to handle service unavailability gracefully.

## Test Categories

### Network Failures
- DNS resolution failures
- Connection refused
- Network unreachable
- Service timeouts

### Missing Dependencies
- OCR engines not installed
- requests library missing
- paho-mqtt not available
- Optional libraries

### API Errors
- Rate limiting (429)
- Authentication failures (401/403)
- Server errors (500/503)
- Invalid responses

### Timeout Handling
- Request timeouts
- Slow responses
- Hanging connections
- Retry logic

## Expected Graceful Degradation

### When Network Fails
- Show cached data if available
- Display clear error message
- Retry with exponential backoff
- Never block UI indefinitely

### When Dependencies Missing
- Disable affected features
- Show informative messages
- Provide alternatives
- Continue with reduced functionality

### When API Errors
- Handle specific error codes
- Implement appropriate retry logic
- Show user-friendly messages
- Log for debugging

## Recovery Mechanisms

1. **Automatic Retry**: Exponential backoff for transient failures
2. **Cached Data**: Use stale cache when fresh data unavailable
3. **Feature Degradation**: Disable features that depend on unavailable services
4. **User Notification**: Clear messages about service status
5. **Reconnection**: Detect when service returns and resume normal operation