xml-dev - Re: Extreme Programming goes mainstream?

[ricko <ricko@geotempo.com>]

From: "Simon St.Laurent" <simonstl@simonstl.com>

> I also liked the unit-testing approach, and it's something I've been
> integrating more and more with own development.  XML seems to have an
> interesting relationship with this aspect, since well-formedness checking
> and validation provide a couple of useful tools for testing certain
aspects
> of software.

If the regression-tests must be prepared with the black-box unit, and if the
turnaround time is so short, then using XP with XML seems to require the
availablility of lightweight, simple XML testing languages.

In the olden days, I was struck by the difference in attitude of people
using DTDs and OmniMark, and people using DTDs that were compiled into
applications. The OmniMark people had a very free approach to tinkering with
the DTDs to perform checks, while the people using compiled-in DTDs never
used DTDs as a way to check data.  I think simple DTDs are pretty
lightweight.   Undoubtedly people who become familiar with XSDL will be able
to use it for ad-hoc tests of particular structures, but I am not sure
whether the power it provides in datatyping provides the kinds of checks
that people need for testing in-progress XML documents.

I think Schematron can fit in here. It has a simple syntax. It is "open" by
default. It lets you test an output document based on an input document
(i.e., black-box testing, not just static testing of output and input
independently).

I was happy to see Kip Hampton's recent implementation of Schematron as a
Perl function: I think it shows a good way to go.  It can be invoked inside
a program for testing preconditions/postconditions.  What is particularly
interesting is that one can add rules and assertions dynamically during the
course of a program.  So if at an early stage you know that the address is
in New York, you can arrange for only the appropriate tests for American
addresses to be loaded into the schema, allowing not just static testing
(e.g. document tests) and end-to-end testing (e.g. blackbox tests) but also
accumulated testing (e.g. whitebox tests).

http://www.ascc.net/xml/resource/schematron/schematron.html

Cheers
Rick Jelliffe