Shift-left means moving quality activities earlier, and it is about when and who, not just running automation sooner. Practical steps are joining backlog refinement and reviewing stories for gaps and testability, running Three Amigos sessions (product, developer and tester agree on examples and acceptance criteria before work starts), joining design reviews to ask where the seams for testing are, adding static analysis and unit tests in CI, and tracking at which stage defects are found. Guides stress that quality becomes a shared responsibility rather than moving to developers alone, and that you still need testing and monitoring on the right side of the timeline.

In a Three Amigos session, Example Mapping (a card for each rule, with its examples and open questions) turns acceptance criteria into concrete cases. You can then write those cases as failing acceptance specs or API contract stubs before development starts.

Sources: Cucumber: Example Mapping, Testomat.io, BugBug guide, DEV Community