I've recently had a little disagreement with fellow developers. We're transforming various ontologies from the original source format (Pica+, RDF, etc) into our data format and have several converters dedicated to exactly this task. The argument came whether or not we should use the full ontology-data file, or create a subset specifically used for testing.
I argued the case for a subset: a custom-created file of all use-cases required to confirm the converters are running correctly. They argued that a production file is always up-to-date and any change in the production file will break the tests. True, I said, but if a change of production files is needed, then invariable the requirements are changed, therefore this is not a fault of using test data. They considered this a very weak argument and summarily decided against the use of a custom-created test-file.
The question, as it boils down to, is whether or not to use the in-production file for testing our converters, or a subset of data. What are the pros- and cons? I'm very much in favor of using a test-file for converting, but I'm willing to assume that my premise is flawed. If I am correct, is there any way in which I can more eloquently and persuasively argue my case?