Cannot use isort with pre-commit hook

[wjdp]

Using a pre-commit config of

repos:
  - repo: https://github.com/akaihola/darker
    rev: 1.3.1
    hooks:
      - id: darker
        args: [--isort]

Yields:

$ pre-commit run
[WARNING] Unstaged files detected.
[INFO] Stashing unstaged files to /home/will/.cache/pre-commit/patch1634135700.
darker...................................................................Failed
- hook id: darker
- exit code: 1

Please run `pip install darker[isort]` to use the `--isort` option.

[INFO] Restored changes from /home/will/.cache/pre-commit/patch1634135700.

It seems darker[isort] is not installed in the environment that pre-commit creates for darker, is there a way to make this work?

[wjdp]

Whoops, found the fix:

repos:
  - repo: https://github.com/akaihola/darker
    rev: 1.3.1
    hooks:
      - id: darker
        args: [--isort]
        additional_dependencies:
          - black~=21.8b0
          - isort~=5.9

Hopefully this helps others!

[akaihola]

Thanks @wjdp for pointing this out! Is there something to improve in the documentation to help others not hit the same problem?