Poka-Yoke

If we think about the very deep principles on which software developers base their work, it's amazing to realize that many concepts are not new at all. Using tests in our code is an effective way to reduce bugs, but the idea has been similarly applied in other contexts several decades ago.

Poka-yoke is a Japanese term that means mistake-proofing or inadvertent error prevention. The key word in the second translation, often omitted, is inadvertent. There is no poka-yoke solution that protects against an operator's sabotage, but sabotage is a rare behavior among people. A poka-yoke is any mechanism in any process that helps an equipment operator avoid (yokeru) mistakes (poka). Its purpose is to eliminate product defects by preventing, correcting, or drawing attention to human errors as they occur. The concept was formalized, and the term adopted, by Shigeo Shingo as part of the Toyota Production System.

The idea behind poka-yoke is that no defect found should...