As per my suggestion [1], transformed the loader verifier code into tests.
- loader_verifier: Transform the verifier into tests
- tests_tasks: Add scenario to check tasks are fine
- test_converters: Add coverage on converters
- Add scenario for archive mercurial loader (success + failure)
[1] https://forge.softwareheritage.org/T1411#26191
Related T1411
Related T1439