Improve tests to validate the correct contents of extracted files

Currently the tests primarily check that the correct number of files are returned from extraction commands. However, as the issue identified in #102 shows this can be insufficient in cases where the underlying library may not be threadsafe (for example). In such cases the tests can still succeed, finding the correct number of files, but their contents may be incomplete. We should develop additional tests that verify for each file type we support that the contents + sizes of each file are correct. Perhaps the easiest method would be with a hash of the contents of the extracted stream.

Inizia individuando i test esistenti per i comandi di estrazione e consulta l’issue #102 per lo scenario di errore. Estendi la copertura a ogni tipo di file supportato, in modo che i test verifichino i contenuti e le dimensioni dei file estratti, eventualmente calcolando l’hash di ogni stream estratto. Il lavoro è completato quando i test rilevano contenuti incompleti anche se viene restituito il numero di file previsto.