Use of test data and programs
The use of test decks, to test the adequacy of programmed (and perhaps of built-in) checks, is not then primarily the task of the auditor. The programmer in fact can only state that he has finished the preparation of a program, after a test deck has run satisfactorily.
It is the task of the auditor to make sure that the test decks used cover most of the situations which are to be tested.