"Obviously a major malfunction."
NASA Space Shuttle Challenger launch engineer
The implications of defect non-detection vary greatly based on what the
product is. No one is likely to die if a $30 spelling checker malfunctions.
On the other hand, most test engineers would rather the products they
work on be shipped as clean as possible.
The reason for this is that
it is very hard to predict what kinds of bugs you will miss if you
chose not to test parts of the product.
In the words of one twenty year veteran, "What you test is what you get.
If you didn't test it, it probably doesn't work."
Why do defects go undetected?
- we thought we could trust a piece of the system, but could not
- we didn't think about some piece of the functionality
- we didn't think about some implication of the design
- we thought about this problem, but chose not to test it
- we thought we had a test, but failed to detect the problem
- we had the test, it would have detected the problem, but it was not
run at the proper time
Copyright 1998 Anne Powelllast update 2/16/98