When you test a program, you want to add some value to it. Adding value through testing means raising the quality or reliability of the program. Raising the reliability of the program means finding and removing errors.
Therefore, don’t test a program to show that it works; rather, you should start with the assumption that the program contains errors (a valid assumption for almost any program) and then test the program to find as many of the errors as possible.
Thus, a more appropriate definition is this:
The Art of Software Testing – Second Edition Page 10 Chapter 2: The Psychology and Economics of Program Testing
” Testing is the process of executing a program with the intent of finding errors “.
Human beings tend to be highly goal-oriented, and establishing the proper goal has an important psychological effect. If our goal is to demonstrate that a program has no errors, then we will subconsciously be steered toward this goal; that is, we tend to select test data that have a low probability of causing the program to fail. On the other hand, if our goal is to demonstrate that a program has errors, our test data will have a higher probability of finding errors. The latter approach will add more value to the program than the former.
A test case that finds a new error can hardly be considered unsuccessful; rather, it has proven to be a valuable investment. An unsuccessful test case is one that causes a program to produce the correct result without finding any errors.
Consider the analogy of a person visiting a doctor because of an overall feeling of malaise. If the doctor runs some laboratory tests that do not locate the problem, we do not call the laboratory tests “successful”; they were unsuccessful tests in that the patient’s net worth has been reduced by the expensive laboratory fees, the patient is still ill, and the patient may question the doctor’s ability as a diagnostician. However, if a laboratory test determines that the patient has a peptic ulcer, the test is successful because the doctor can now begin the appropriate treatment. Hence, the medical profession seems to use these words in the proper sense. The analogy, of course, is that we should think of the program, as we begin testing it, as the sick patient.
HAVE WONDERFUL TESTING…
Art of Testers 