Agile Attitudes- Unit testing

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Agile Attitudes
Volume 1, Issue 10                                    Oct. 21, 2004
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                    Unit Testing
                  by Ron Morsicato

One of the most serious mistakes I've seen in my career is a
software development team's acceptance of an attitude that
unit testing has to be bypassed in order to maintain production
goals, or simply that unit testing need not apply to this team
because of its seasoned and deeply knowledgeable makeup. The
team's management certainly will like the ideas that they could
save development costs or that they have the cream of the crop
working for them. After all, there's plenty of opportunity to
catch bugs during acceptance testing.

Invariably, the project suffers the consequences. You see, if
you rely on testing on the acceptance level, you will have
experienced the result of black box testing, which does not
guarantee that all possible execution paths have been tested.
Neither will it insure that during the execution of the
software that all its internal workings remain as intended.
Acceptance testing just tells you that you did not observe any
software misbehavior given the inputs you provide.

The failure to properly unit test software leads to a buildup of
latent defects. Latent defects too often emerge after the software
has been fielded, and the consequences to customers' views on
the reliability of your product can be devastating. Even if the
error is detect during acceptance testing, it holds up the
release process, a problem that is exacerbated since is it often
the case that the source of the defective behavior may not even
be in the modules that were worked on prior to the release. This
can stop an entire team in its tracks.

Unit testing is really just part of a simple code development
pattern. Recognizing this, the open source community has developed
a stockpile of unit testing frameworks covering just about every
programming language. Using these frameworks, most users observe
that production is even increased! For a fairly inclusive list and
brief description of unit testing frameworks take a look at
http://testingfaqs.org/t-unit.html#cUnit.


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