Agile Testing
Shift-Left Testing
Moving testing activities earlier in the development lifecycle to find and fix defects sooner and cheaper.
Full definition
Shift-left testing means performing testing activities earlier in the software development lifecycle. The concept is based on the fact that finding and fixing bugs is exponentially cheaper the earlier they're caught.
Cost to fix a bug (IBM Systems Sciences Institute):
- Requirements phase: $1 (baseline)
- Design phase: $5
- Development phase: $10
- Testing phase: $20
- Production: $150
Shift-left practices:
- Requirements review: QA reviews requirements for testability and completeness
- Early test design: Write test cases before code is written
- Static analysis: Automated code scanning during development
- Unit testing: Developers write tests alongside code
- Code reviews: Peer review catches defects early
- TDD/BDD: Tests drive development
QA's role in shift-left:
- Participate in requirements and design discussions
- Help write acceptance criteria before development
- Perform risk analysis early
- Set up automated quality gates in CI/CD
Shift-left doesn't mean eliminating later testing — it means adding earlier testing to catch defects sooner. You still need integration, E2E, and UAT testing.