Test While Developing (TWD) is a mindset, not a checklist.
It’s about writing tests as you build — not afterward, not someday, not just when you’re done.
TWD is for developers who want faster feedback, deeper confidence, and fewer regressions — without the ceremony of traditional testing philosophies.
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Write tests while building, not after
Testing is part of the development flow — not something you add at the end. -
Keep your test runner open
Let your tests run continuously while coding to get fast, meaningful feedback. -
Automate what you already check manually
If you’re repeating a check by hand, it’s a good candidate for a test. -
Let real use guide what you test
Focus on the behaviors and flows your users actually rely on. -
Use coverage to find gaps, not for validation
Don’t chase numbers — use coverage tools after the fact to spot what you missed, not to prove anything. -
Prefer fast feedback over strict structure
Don’t get stuck on test types or formats — prioritize feedback that helps you move forward. -
Design features to be easy to validate
Write code that’s naturally testable and easy to observe as you develop.
See TWD in action:
TWD isn’t about writing more tests — it’s about writing the right ones, at the right time.