Currently, it requires everyone who uses single quotes to run black and then have a second tool (we use pre-commit double-quote-string-fixer) to ensure that single quotes are being used consistently.
From black documentation:
If you are adopting Black in a large project with pre-existing string conventions (like the popular “single quotes for data, double quotes for human-readable strings”), you can pass
--skip-string-normalizationon the command line. This is meant as an adoption helper, avoid using this for new projects.