# Test-Driven Development

Write a failing test first, then the code to pass it.

## What is **Test-Driven Development**?

**Test-driven development** (TDD) means writing a failing test first, then the minimum code to pass it, then tidying up.

Level: Apprentice · [More Unit Testing terms at this level](https://www.ask-codey.com/glossary/subjects/unit-testing/apprentice)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/test-driven-development