# Unit Testing glossary: Master level

3 Unit Testing terms at the Master level, each with a short definition and a link to its full page.

Updated: September 27, 2026

[Study these as flash cards](https://www.ask-codey.com/decks/unit-testing/master)

- [Approval Testing](https://www.ask-codey.com/glossary/approval-testing): Comparing output against an approved file.
- [Characterization Test](https://www.ask-codey.com/glossary/characterization-test): A test recording what existing code does today.
- [Mutation Testing](https://www.ask-codey.com/glossary/mutation-testing): Deliberately breaking code to check tests notice.

- Previous level: [Freelancer](https://www.ask-codey.com/glossary/subjects/unit-testing/freelancer)

[Every Unit Testing term, by level](https://www.ask-codey.com/glossary/subjects/unit-testing)

Source: https://www.ask-codey.com/glossary/subjects/unit-testing/master