Jeff D. Chastain wrote, On 12/21/2006 4:00 PM:
This is a cross-post with CF-Talk, but I figured this list is a bit
more cfc oriented. I am really trying to get into test driven
development as the benefits are fairly obvious after having done
development any other way. However, in terms of doing this with
ColdFusion, I am either not getting it or there is a lot of talk going
on regarding TDD, but not much in actual practice.
My biggest issue comes with object dependencies. Ideally, your
objects are as loosely coupled as possible, but it is simply not
possible to have an application full of completely disjoint objects
with no dependencies at all. One of the premises of unit testing
though is to test only the functionality of one individual object or
unit and not test all of its dependencies. Other languages appear to
handle this with mock objects which allow for simulating and testing
any object dependencies.
Of course, you could directly test those too.
However, the mock object frameworks for Java and other languages
simply don't port to ColdFusion because of language construct
differences. Without a mock object framework, the only other option I
see is to hand create and maintain stub or mock objects, and this just
does not seem like a feasible practice in an application of any size.
A while back, I thought of attempting to develop a mock object framework
for CF (or better put, I thought about thinking about it). But, as I
explain below, I haven't seen much use for one in my own development, so
I've pretty much dropped the idea.
So, how do you test ColdFusion objects when there are dependencies
involved?
I haven't yet found myself in need of a "true" mock. In cases where
I'm testing class A which does have a dependency B, I go ahead and
create the stubs in B as I need them, and let that class grow into the
real thing over time, as needed. I don't think there's anything wrong
with integration tests - in fact, we need those too. In the cases where
I have needed "unit" tests (in the proper sense of the term), I might
then go ahead and hand create class C, which is basically a "mock" that
extends B. It's not really a mock (well, we had a huge discussion about
this on the TDD list a couple of months ago), but it serves the purpose
of basically truly isolating A. In any case, I don't find that need
happening often. Further, I haven't noticed that I've ever gotten into
trouble when something in B breaks the tests for A - it's normally
pretty obvious, even if it doesn't break the tests for B. In fact, I've
often had more trouble with my fake "mocks" than with my integration
tests. Of course, this phenomenon is not unique to me in Coldfusion.
I've also experienced it in Java. Ron Jeffries talked about never (or
very rarely) needing to use a "proper" mock as well.
Does that make any sense?
-Sam
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