Testing Failure Scenarios With Feature Flags

Designing for failure is crucial when developing distributed systems. One challenge in this regard is ensuring that failure paths are adequately tested. Automated tests can help identify bugs and reduce manual quality assurance efforts. Feature flags can be used to trigger various failure modes, enabling comprehensive testing of all code paths. LaunchDarkly recently implemented a data export service with a resilient retry mechanism using SQS for its event processing pipeline. They also developed an end-to-end method for testing crucial error paths by feature flagging the way events are exported. This approach allows for the simulation of failure scenarios, ensuring that error handling logic is working correctly and providing confidence in the system's resilience to failures.