Would it be possible to create the test files locally and obtain a checksum (MD5 for example) for each? Then when you create them via your tests you need only check whether the checksums match.
Digest::MD5 is a core module, so you could use that quite safely, and not have to worry about unnecessarily adding to the download/install burden.
That's the way I would go at least.
--
Barbie | Birmingham Perl Mongers | http://birmingham.pm.org/