Build Quality In

W. Edwards Deming, a key figure in the history of the Lean movement, offered 14 key principles for management. Principle 3 states, “Cease dependence on inspection to achieve quality. Eliminate the need for inspection on a mass basis by building quality into the product in the first place.”

It’s much cheaper to fix problems and defects if we find them immediately—ideally before they are ever checked into version control, by running automated tests locally. Finding defects downstream through inspection (such as manual testing) is time-consuming, requiring significant triage. Then we must fix the defect, trying to recall what we were thinking when we introduced the problem days or perhaps even weeks ago.

Creating and evolving feedback loops to detect problems as early as possible is essential and never-ending work in continuous delivery. If we find a problem in our exploratory testing, we must not only fix it, but then ask: How could we have caught the problem with an automated acceptance test? When an acceptance test fails, we should ask: Could we have written a unit test to catch this problem?