When is unit-testing bad? [was: Re: does lack of type...]

[Aurélien Géron]

> In article <87of0pno5s.fsf at titan.staselog.com>,
> Edvard Majakari  <edvard+web at majakari.net> wrote:
> >
> >I'm rather interested in (and fond of) unit testing as well as TDD, so I
> >though to share my opinions. I once discussed TDD with my friend in here,
> >and the common agreement seemed to be that TDD is not a silver bullet -
> >often there are types of computational modules that are very hard to unit
> >test, eg. think of graphical user interfaces or complex systems, where
> >forking or threading is concerned.
> .
> .
> .
> While we're all being rational enough to look at bundles of
> costs and benefits, this observation hints at a different
> insight:  that it's possible to *design* for testability.
>
> Yes, GUIs and forking and threading are hard to test.  SO
> DON'T DO THEM.  Or, as I prefer, adopt models of GUI and
> concurrency development that lend themselves to testing.
>
> At this point, I should explain what I mean by that.  I
> haven't yet figured out how to say it in less than a book;
> therefore, all I can contribute for today are the slogans
> above.
>
> If you're in a situation where unit-testing is bad, you're
> probably in a bad situation.  Change your situation.
> -- 
>
> Cameron Laird <Cameron at Lairds.com>
> Business:  http://www.Phaseit.net
> Personal:  http://phaseit.net/claird/home.html

I think I sort of understand what you mean, Cameron, but IMHO it looks to me
that you are trying to fit everything into one vision ("Everything looks
like a nail when you have a hammer").

There are things that are hard to unit test (I'm talking about automated
unit tests here) and which you just can't do without in some projects.  For
instance, the database!  I worked in a couple of projects with automatic
unit tests for the DB related components, and having lived through it, I'm
not sure that it was worth it at all!  Manual unit tests would have made
much more sense.  The same goes for GUIs.  I'd be interested to know about
projects where they automate unit tests for GUIs, but I suspect it would be
just as cumbersome. And live without threads?  A lot of projects would be
better off not using them, I agree with that, but some projects just can't
do without them!  Web sites are also horrible to automatically unit test.
In all those cases, I much prefer having a human being go out and do the
unit tests manually.

I guess my point is that though you may be right in some specific contexts,
I don't think you can generalize.  That's IMHO of course.

I may not have understood exactly what you meant, though.  You may want to
send me a copy of your book?  ;-)

Aurélien