The current test verifies in a simple way that the file was properly copied by comparing the size of the source file (supplied by the data provider) with bytes of stream data moved to the destination (no `filesize()` involved).  A better test would omit the count value from the data provider entirely, and do the `filesize()` within the test method itself.  An even better test would compare hashes of the source and destination files to assure that the copy remains intact.  Either way, using a constant value in a code file for a byte count/hash of a file external to the test seems unwise.