We should test that all KeyValueFileManagers support empty files. This will be needed for #241 where we are moving away from creating pyproject.toml eagerly and creating it from within the add config method, but that requires the ability to create an initial empty file. My inclination is that empty files should always be valid and just correspond to an empty map.
Originally posted by @nathanjmcdougall in #663
Originally posted by @nathanjmcdougall in #663