What problem does it solve?
TDD prevents unverified code changes by forcing you to write a failing test first, so you only implement what you have explicitly specified and can automatically guard against regressions.
Core Features & Use Cases
- Failing-test-first discipline: Ensures every production behavior is justified by a test that initially fails, then passes.
- Red-Green-Refactor loop: Drives a tight cycle of writing the test, verifying the failure, implementing the smallest change to pass, and only then cleaning up.
- Regression-proof debugging: When a bug is found, it is reproduced in a new failing test before making the fix, so the fix is proven and preserved.
Use case example: You’re adding a new retry behavior to a function—write a test that fails because the retry doesn’t exist yet, implement the minimal retry logic to make the test pass, then refactor for clarity while keeping the tests green.
Quick Start
Ask an AI to guide you through writing a failing test first, running it to confirm the failure is real, implementing the minimal code to make it pass, and refactoring without changing behavior.