"The real value of tests is not that they detect bugs in the code, but that they detect inadequacies in the methods, concentration, and skills of those who design and produce the code."

How Did Software Get So Reliable Without Proof? Lecture Notes in Computer Science vol 1051 1996 pp. 1-17 : FME '96: Industrial Benefit and Advances in Formal Methods, Third International Symposium of Formal Methods Europe, Co-Sponsored by IFIP WG 14.3, Oxford, UK, March 18-22, 1996, Proceedings.