Program testing can be used to show the presence of bugs, but never to show their absence!
- Edsger Dijkstra - [1972]Quoted in More Programming Pearls, Column 6: Bumper-Sticker Computer Science Quoted in More Programming Pearls, Column 6: Bumper-Sticker Computer Science
 
A good threat is worth a thousand tests.
- Boris Beizer - [1990] about publicizing test cases to programmers , Software testing techniques by Boris Beizer , ISBN: 0442206720