Hardware take on software testing.

[Peter Hansen]

Paddy McCarthy wrote:
> 
> If software were tested like hardware...
[snip]
> I ask because I value the view of Pythonistas and if you look at the
> electronic/Software products you buy today, a lot go out the door with
> bugs. The software industry has relied on the fact that it doesn't
> cost them much to make another release but if you look at the
> proliferation of updates out there it doesn't seem to be working.
> Customers should expect more.

Actually, the conditions under which software and hardware are developed
are quite different in some ways.  Those differences can make it quite
inappropriate to treat the two the same.  New approaches that are being
explored for software development, which would likely be fundamentally 
infeasible for developing hardware, can be collectively labelled "agile
processes".  At the heart of one of these processes, Extreme Programming,
is a new approach to design, testing, and coding, called Test-Driven
Development (TDD).

With the TDD approach, tests are written first (actually, you start with
only one test), then executed to prove that they fail ("red light"), then 
just enough code is written to make the test pass.  Once the test passes 
("green light"), the code is refactored to make sure it is clean and 
proper, the tests are re-run to ensure nothing has broken, and work 
proceeds on implementing the next test.

I'm unsure this approach would be of much use in most kinds of hardware
development, because the costs associated with incremental development 
and refactoring are so much higher.  With software, however, which is 
a purely virtual product, these costs are negligible and the benefits 
quite high.

So to answer the question that you didn't actually get around to asking
explicitly: I don't think testing software like hardware would be a good
idea, but I also don't think there's a need as we seem to have developed
other approaches which are sufficiently good that they could well eliminate
the situation where "a lot go out the door with bugs".  Time will tell,
but those of us applying these new techniques are so far generally 
satisfied, or even ecstatic, with the results.

-Peter