This was started by Fionera, finished off by Laura with fixes and more
docs from Nick.
Co-authored-by: Fionera <fionera@fionera.de>
Co-authored-by: Nick Craig-Wood <nick@craig-wood.com>
We now have a backend (fichier) which doesn't support 0 length
files. Therefore all 0 length files in the tests have been replaced
with length 1.
In a future commit we will implement a test for 0 length files.
