4.1What Is Shift-Left?

Shift-left means moving testing activities earlier in the development lifecycle. Instead of finding bugs after code is written, prevent them before code is written. The earlier a defect is found, the cheaper it is to fix.

Traditional:     Requirements → Design → Code → Test → Deploy
                                                  ↑
                                            Testing starts here

Shift-Left:      Requirements → Design → Code → Deploy
                      ↑              ↑         ↑
                      |              |         |
                   Review         Review    Unit tests
                   criteria       testability  during dev
                   with QA        with QA