Add stylelint

[bollwyvl]

References

• the last steps of https://github.com/jupyterlab/jupyterlab/issues/11943
• mostly copies https://github.com/jupyterlab/jupyterlab/pull/11944

Changes

• adds stylelint, with prettier integration
  • as stylelint --fix can actually make substantive changes, e.g. ordering of properties associated with a selector, it gets called before prettier, which handles the cosmetic changes, e.g. whitespace
• adds commands for running prettier explicitly
• trims down a bunch of jlpm run to jlpm
• adds caches for eslint/stylelint
  • this fairly quick starts shaving off tens of seconds, making the linters more likely to be run
• runs all the linters in CI

Discussion

While I generally think starting out with more guidance towards standard compliance and best practices in as many domains as possible, is desirable to save pain down the line, I guess this (and other linters) could be made optional. So long as a project doesn't make tsc and webpack fail, it's technically fine.

Even so, I'd probably make them opt-out, so cookiecutter.json would look more like:

  "use_prettier": "y",
  "use_eslint": "y",
  "use_stylelint": "y",

They could still then all be run with jlpm lint and jlpm lint:check.

[fcollonval]

Thanks a lot for starting this.

  "use_prettier": "y",
  "use_eslint": "y",
  "use_stylelint": "y",

I'm always reluctant of adding more options to the cookiecutter (I wish it came with a way to do basic and advanced configuration :cry: ). This exposes more tooling to the beginners and because answering no to those will likely be a corner case.

[bollwyvl]

more options to the cookiecutter

Yeah: cookiecutter hasn't really evolved much from a user perspective, even if it can do more powerful things. I liked the yeoman user experience better, but you still have to pay the npm tax to get in the door... but it had a more robust concept of storing the choices made, such that you could re-run the generator to update things... or have sub-generators that worked harmoniously.

Anyhow: as linting isn't currently exposed on the cookiecutter, i'd just leave this one... or discuss on a related PR.

Another thought (for another PR): for all three of the linters, we could move all of the config to package.json... though I don't think there's a way to put the file ignores in.

[bollwyvl]

• https://github.com/jupyterlab/jupyterlab/pull/11944 was merged, so have taken off draft status.
• https://github.com/jupyterlab/jupyterlab/pull/11993 has revealed some more patterns to apply here, namely avoiding rewriting vendor prefixes, as we don't use an postprocessor that would add them

[fcollonval]

Merging