Program testing can be a very effective way to show the presence of bugs, but it is hopelessly inadequate for showing their absence. - Edsger W. Dijkstra

Program testing can be used to show the presence of bugs, but never to show their absence!

Testing can only prove the presence of bugs, not their absence. –

Testing shows the presence, not the absence of bugs

The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.

In short, I suggest that the programmer should continue to understand what he is doing, that his growing product remains firmly within his intellectual grip. It is my sad experience that this suggestion is repulsive to the average experienced programmer, who clearly derives a major part of his professional excitement from not quite understanding what he is doing. In this streamlined age, one of our most undernourished psychological needs is the craving for Black Magic and apparently the automatic computer can satisfy this need for the professional software engineer, who is secretly enthralled by the gigantic risks he takes in his daring irresponsibility. For his frustrations I have no remedy......

Are you quite sure that all those bells and whistles, all those wonderful facilities of your so-called "powerful" programming languages belong to the solution set rather than to the problem set?