What Is Test-Driven Development (TDD)?
Test-Driven Development is a workflow where you write a failing test for a small piece of behavior first, then write the minimum code to make it pass, then r...
Published October 8, 2026
Test-Driven Development is a workflow where you write a failing test for a small piece of behavior first, then write the minimum code to make it pass, then refactor — repeating this cycle for each new piece of functionality.
Why it exists
- Writing tests after the code is often skipped under time pressure, or ends up only testing what the code already happens to do
- Writing the test first forces you to clarify exactly what the code should do before writing it
How to apply it
- Follow the "red-green-refactor" cycle: write a failing test (red), make it pass with minimal code (green), then clean up the implementation (refactor)
- TDD naturally produces a comprehensive test suite as a side effect, since every piece of behavior has a test written specifically for it
FAQ
Is TDD required for good testing?
No — writing thorough tests matters far more than the specific order they're written in. TDD is one disciplined approach to get there, not the only valid one.