regression-and-parity-check

To detect regressions during a code migration, compare current changes against a historical baseline. This parity verification process requires a behavior catalog or test suite, access to historical outputs, and a deviation taxonomy to classify differences accurately.

Yes, you can enforce functional parity as a release gate by comparing current changes against a baseline. This ensures observable behavior is preserved and prevents regressions from reaching production during critical refactors or finalization.

The best way to classify deviations during baseline comparison is by using a clear deviation taxonomy. This taxonomy separates detected differences into three specific categories: Bug, Spec Gap, or Accepted Deviation.

Yes, you need a behavior catalog or test suite to verify functional parity. Access to historical outputs and a clear deviation taxonomy are also required to classify differences and detect regressions accurately.

You should run a parity check after implementing a feature or during critical refactors. This generates a parity report and regression log, classifying deviations to ensure observable behavior is preserved against the baseline.