Extreme Programming Explained: Embrace Change, Second Edition

Chapter 13. Testing: Early, Often, and Automated

Defects destroy the trust required for effective software development. The customers need to be able to trust the software. The managers need to be able to trust reports of progress. The programmers need to be able to trust each other. Defects destroy this trust. Without trust, people spend much of their time defending themselves against the possibility that someone else may have made a mistake.

It is impossible to eliminate all defects, however. Increasing the mean time between failures from one month to one year seems extremely expensive, and the cost to increase it to one century, as is required for code like that flying in the space shuttle, is astronomical.

Here is the dilemma in software ...