Lorenzo Jorquera
4/28/2005 8:19:00 PM
Eric Schwartz <emschwar@pobox.com> wrote:
"Dave Fayram" writes:
> I'd much prefer to see (this is pseudo and formatted for short lines,
> so bear with me):
>
> def my_appropriately_named_test
> long_name = "This name is far too long."
> assert_raise Module::InputValidationError,
> @inst.the_func( long_name )
> end
>
> Then I can test it. If I ever make a change and accidently invalidate
> it, then I'll know. If we ever eliminate that restriction, the test
> will break and we'll know to update it.
How will you know if it's the test or the code that's broken? Without
comments in the_func telling you why that exception is raised, you
could end up fixing the wrong problem.
When you run your unit tests very often (tipically several times an hour) you will know exactly why the test failed.
A not-uncommon case is that you have to call into a 3rd-party C or C++
library (the infamous Jukebox example in Pickaxe 1, for instance), and
that library enforces some restrictions that aren't necessarily
obvious. Let's say we have implemented the infamous Jukebox
application only supporting ASCII song titles, and we now want to add
support for UTF-8. Since it's been some time, and the original coder
has moved on to another company, we've forgotten that libjukebox
doesn't work with, say, UTF-8.
If I had a comment in the_func saying:
/* libjukebox can't handle songs with UTF-8 encoded titles */
raise Module::InputValidationError if has_utf8?(title)
That helps me a lot more than just:
raise Module::InputValidationError if has_utf8?(title)
In the latter case, I might just think, "Okay, they didn't want to
support UTF-8 in revision 1, so now i can take it out." In the former
case, I know *why* they didn't support it, and it wasn't because they
were lazy, or pressed for time. So instead of removing the code, and
its associated test, I know to ask Jukebox, Inc. for a new library
that does support UTF-8.
In this case, I would prefer a more especific exception:
raise Module::LibjukeboxCantHandleUTF8 if has_utf8?(title)
Lorenzo.
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