Dumping is covered in the respective adapters but backup (copy) and directories creation are not (from the abstract FileDumper). To test them I see three possibilities :

- the NullDumper like I did
- a ConcreteFileDumper in the Tests folder (the same than the NullDumper but outside the prod)
- repeating this logic in each adapter (which is wrong IMO)

The same question applies to test the logic of changing the template because it is done in the abstract FileDumper.