Re: Unit Testing in C++

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 25 Jun 2008 09:09:39 -0700 (PDT)

Message-ID:

<4c8b5966-ea8e-4563-b8c3-3177ad123ec2@25g2000hsx.googlegroups.com>

On Jun 25, 5:06 pm, Noah Roberts <u...@example.net> wrote:

Ian Collins wrote:

James Kanze wrote:

On Jun 25, 7:01 am, Ian Collins <ian-n...@hotmail.com> wrote:

It looks like the OP is facing a common problem caused by
adding unit tests after the fact, rather than designing them
in form day -1.

I'd express it a bit differently: if adding unit tests after the
fact does cause problems, then it's often (but not always) a
symptom of poor design and unnecessary coupling. Which in the
long run, causes problems not just for testing, but for other
things as well.

Good point.

I disagree. It isn't that good of a point. Unit testing is
meant to be done ahead of the time and guides the design
process.

And how do you know what to test if you haven't done some high
level design? How do you even know what other classes might
exist, to interact with them?

Even if you're not going to be building the test ahead of time
you should be thinking about how you will.

Testing is part of the overall quality proceedure, and
certainly, one should be thinking about it up front. But you
still need to think about what the class is supposed to do, and
how it interacts with the other components, before you can write
either the class or its tests.

Your original point was well placed. What Kanze is saying is
sort of true, but doesn't change anything with regard to your
original point and simply places the unit test coding in the
wrong place: after production coding.

When the actual code gets written is largely irrelevant. If
writing the tests first helps you to think about how to design
the class internals, fine. But it's hardly a critical issue.
(And I don't see the relationship with whether you need to hack
some sort of struts, rather than using the actual classes.)

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