Royal Pain
James Knott
james.knott-bJEeYj9oJeDQT0dZR+AlfA at public.gmane.org
Fri Jun 18 14:28:02 UTC 2004
Lennart Sorensen wrote:
> On Fri, Jun 18, 2004 at 07:27:26AM -0400, James Knott wrote:
>
>>And of course, it's impossible to prove there are no bugs. You can only
>>fail to find some.
>
>
> That is actually not true. If you have a well defined specification of
> what the behaviour of each piece of the program must be for specific
> inputs, you can actually prove the behaviour of each part of the program
> correct. This is in fact done at some software companies. It is
> certainly a lot more work and costs more. It requires proper bounds
> checks, and full coverage testing at the very least.
Of course, you have to make sure you can test for everything that might
cause a problem. There may be some circumstance that you hadn't
considered that may cause problems. This happened to me once at IBM. I
was doing intengration testing of a new standard desktop system.
Everything checked out OK. But, after release, one user had a font
problem, with one of the applications that I supported, when used with a
printer that I hadn't tested with. I hadn't tested with that printer,
simply because we didn't have one of that model in the test lab. The
cause turned out to be a conflict between the installation of two
applications and reversing the install order solved that problem. When
you're doing integration testing of a complete system, it's physically
impossible to test for all possible conditions, to verify there's
absolutely no bugs.
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