paranoid programming
professional programming

    A programming style that tries to prepare for
   the worst external conditions, including incorrect input,
   resource limitations, hardware and software failure and even
   can't happen errors, to the fullest possible extent.  While
   some believe in the motto "professional programming is
   paranoid programming", the expression usually has the
   connotation that the efforts are unnecessary or too costly
   ("Maybe this code is just paranoid programming, but I think it
   is necessary to avoid a possible overflow condition".)

   (2001-01-27)