“The job of tests, and the people that develop and runs tests, is to prevent defects, not to find them. A quality assurance organization should champion processes that build quality into the code from the start rather than test quality in later. This is not to say that verification is unnecessary. Final verification is a good idea. It’s just that finding defects should be the exception, not the rule, during verification. If verification routinely triggers test-and-fix cycles, then the development process is defective.”
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Mary Poppendieck,
Implementing Lean Software Development: From Concept to Cash