Perfect Software And Other Illusions About Testing

by Gerald M. Weinberg

Testing has its roots in psychology, in the study of the behavior of the human brain. If humans were perfect thinkers, we wouldn't need to test our work. If we were unemotional robots, we would always use testing in a rational way, to reduce risk in our decisions. If we were identical clones, we would all assess risks in the same way. But we are imperfect, irrational, value-driven, diverse human beings. Therefore, we test, and we test our testing.

Believing in objectivity:

Information is neutral, but people's reactions to information are rarely neutral. To assess testing information, you must take into account people's emotional defenses—repression, rationalization, projection, displacement, overcompensation, and compulsiveness. By remaining vigilant, thoughtful, and pragmatic, you can help diffuse emotional chaos and prevent illogical processes from undermining your testing efforts.

Common Mistakes 1. Failing to notice when people are fearful: Defense mechanisms are usually easy to spot if you're looking for them. 2. Creating a fearful environment: If you blame messengers for bringing news you don't want to hear, you'll be rewarded by not hearing the news you should hear. 3. Allowing your fears to override the facts when making decisions: To succeed in the software business, you need to be aware of your own rules and how they distort your intake of information. 4. Allowing your hopes to override facts when making decisions: It's all right to hope for anything, but hoping is not the same as expecting anything. [8] 5. Indulging in compulsive behavior: One person's compulsiveness frequently engenders fear and defensiveness in others. Your first priority should be to strive to be reasonable. 6. Assuming that any argument against your own point of view is part of a pathology: In the same way that a rationalization can sound like a good argument, a good argument can sound like a rationalization. Many people are uncomfortable making arguments. Many are untrained in the art of persuasion. Learn to listen sympathetically to objections and justifications. Try to find and honor what's worthwhile in an opposing viewpoint—there's almost always something there to value. For instance, the argument "It's too hard to fix that" might be the speaker's way of saying, "I don't know how to fix that quickly or cheaply, and I'm not convinced doing so would be a good way to u...

You must treat everyone equally, but not necessarily in the same way.

Insert known bugs without telling the testers, then estimate the number of remaining unknown bugs by the percentage of known bugs they find.

try this

• Does it at least cover what matters most? You can't generally test every path (remember

If you discover that others are more willing to accept information you have to convey when another person delivers it, think of the knowledge as a test result.

an Internet riddle: Q: "How do you know if you're from California?" A: "You know you're from California when your wife says 'pick up Granola on the way home,' and you go to the day-care center."