Definition
Shift-left testing moves quality activities earlier in the SDLC. Instead of QA being a 'gate' at the end, testers collaborate with developers, product managers, and designers from day one.
Practices that count as shift-left
- Three Amigos meetings on every story
- TDD / BDD at the unit and acceptance level
- Static analysis (SonarQube, ESLint, ruff) in pre-commit hooks
- Contract tests in CI before deploy
- Threat modeling in design reviews
Why it matters
IBM's classic data shows a defect costs ~6× more in QA than in design, and ~100× more in production. Shift-left cuts that bill and shortens lead time for changes — a key DORA metric.