Re: [xml-dev] Testing XML don't use xUnit

[Michael Kay <mike@saxonica.com>]

>> 
>> It sounds like you are suggesting it's bad to have xpaths in junit
>> tests?  ...and to use Schematron instead?
>> 
> 
> Yes. Because changes to the structure of the xml will break the JUnit
> test whereas Schematron assertions are resilient to that.
> 

I'm completely bemused. I thought Schematron assertions, like XMLUnit assertions, were both XPath. Why is one better than the other?

Unit testing has always been exposed to the problem that when things change, tests break. My response to that has always been to have very little internal testing - the vast majority of tests are "black box" tests working against stable product interfaces rather than against internal components, because internal components change much more than external product interfaces. But XPath has proved a very good language for writing the assertions, and I've always thought that is why both Schematron and XMLUnit use it - as do the latest generation of W3C test suites, with considerable success.

Michael Kay
Saxonica