snapshot-testing

Snapshot testing prevents unintended changes by comparing current API surfaces and serialized outputs against human-reviewed baseline files, detecting regressions automatically without requiring explicit assertions.

You verify API surfaces and HTTP responses by capturing the output with the Verify library, which generates a baseline file for human review and automatically diffs future runs to detect breaking changes.

Yes, snapshot testing validates serialized JSON outputs by comparing the refactored data model's serialization against an approved baseline, ensuring downstream systems are not affected by unexpected output changes.

Yes, snapshot testing requires explicit developer approval when modifications are detected, ensuring that any changes to rendered HTML, HTTP responses, or API surfaces are intentional and reviewed before updating baselines.

The best way to detect breaking changes in public APIs is using snapshot testing to capture the API surface, compare it against approved baselines, and flag any unintended modifications for explicit developer review.

You should avoid snapshot testing for output verification when outputs are highly volatile or non-deterministic, as the automated diffing against baseline files will require constant manual approval and diminish the value of regression detection.