unknown

Replay testing is a technique for event-sourced systems that replays the entire production event history through a new code version to validate backward compatibility and correctness. Two oracle types are covered: implicit oracles (crash-free execution) and explicit oracles (comparing final state against known production snapshots). The approach enables A/B testing of new business logic against historical data without production risk. Key practical challenges include handling non-determinism (clocks, external APIs), event schema evolution via upcasting, silencing side-effect adapters to prevent real emails or payments, and GDPR compliance through crypto shredding or pseudonymisation. Replay testing complements—not replaces—unit and end-to-end tests, serving as the ultimate regression safety net for complex domain refactorings.

Replay Testing

Welcome to PHP Dev, a dedicated space for sharing knowledge about PHP and its ecosystem (only PHP directly related).
Help us find good articles and blogposts and provide links. Upvote or downvote, after reading, it's essential

PHP Dev

Replay testing is not magic, but it feels like it. It is the only type of test that works with 100% realistic data without taking the risks of testing in production.

<p>Replay testing is not magic, but it feels like it. It is the only type of test that works with 100% realistic data without taking the risks of testing in production.</p>