[wp-hackers] Unit Testing, Yet Another Discussion

[Sam Angove]

On 8/3/07, Jacob Santos <jacobsantos at branson.com> wrote:
>
> If you start out with the most difficult, then yeah, it will be depressing and
> the more depressing something is, the easier it is to give up.
> Preventing regressions in return values, is my main concern and
> something that should be prevented by unit testing, both the easy and
> more difficult functions (which are more likely to be updated).

I don't want to give the wrong impression: I really, really want to
see automated tests for WordPress, and I'm glad to see someone doing
it.

It's not just a matter of difficulty, though. Proper unit-testing
means that units are tested in isolation, with mock objects etc.
substituting for other components.

The problem with this approach in WordPress is that it uses mostly
functions, not classes. If `foo()` and `bar()` are in the same file,
and `foo()` calls `bar()`, you can't use a dummy version of `bar()`.
If `bar()` calls `baz()` and ten of its closest friends, you can't use
dummy versions of any of them. Or, rather, you can, but you end up
with a harness that's ten times more complicated than WordPress is.

It's difficult, *and* it reduces agility, *and* it increases
maintenance costs -- the tradeoff isn't worth it.

The alternative is to test the functions as a group, which is really
closer to functional testing... It should still catch (some?)
regressions, and having stable, tested interfaces would make it safer
to refactor "difficult" functions into a form more amenable to smaller
units. I gave up on *that* because the only way I could see to do it
properly required more up-front work building the harness than my
limited interest allowed. YMM(hopefully!)V.


> If enough people
> get started then it will be easier for others to add, modify and improve
> upon existing tests. [...]
> I'll be back with any results and post all unit tests that I complete.
> At least in the future there will be something.

If you set up an open repository somewhere (Google Code?), I'm happy
to pitch in -- at the very least I can convert my existing formatting
tests to whatever framework you're using.