Move eslint/prettier config to packages/eslint-config-react-native

[dratwas]

Summary

Basing on discussion from this issue - react-native-community/discussions-and-proposals#65 we moved ESLint/Prettier config to its own package inside packages directory.
At this moment we had to left all eslint dependencies in root package.json since eslint-config-react-native is not published yet.

Changelog

[General] [Changed] - Move eslint/prettier config to packages/eslint-config-react-native

Test Plan

Lint returns same numbers as before
yarn lint output:

✖ 80 problems (0 errors, 80 warnings)

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[michalchudziak]

Thanks, @dratwas!

@matt-oakes @cpojer could you take a look? We'll probably need your help with BUCK file if it's required.

Also, we were wondering if the new config should be included as a dependency in root package.json? For now, we just extended eslint config with a relative path to the package. We believe that it might not be the ideal solution. WDYT?

[matt-oakes]

Looking good!

React Native has some custom prettier configuration in the root package.json (https://github.com/facebook/react-native/blob/master/package.json#L13-L20).

With this PR, the Prettier config for core React Native and users of this ESLint configuration would be different unless the users include the same Prettier configuration.

It is possible to specify the options in this ESLint config, however, it is not recommended because most editor plugins will not read the options and will give inconsistent results.

As I see it, there are three options:

1. Ensure that all users of this ESLint config also have the same PRettier config included.
2. Accept that the prettier config might be different across projects, but that it will at least be standard within the project.
3. Change the React Native core to just use prettier with the standard configuration and no customisation to ensure that it is consistent by default.

[gengjiawen]

@matt-oakes We have eslint-plugin-prettier, there should be no format collision

react-native/package.json

Line 124 in fc91bcc

"eslint-plugin-prettier": "2.6.0",

[matt-oakes]

@gengjiawen The plugin is there, but I think that the core React Native repository has some custom settings, seen here in the package.json https://github.com/facebook/react-native/blob/master/package.json#L13-L20.

These will be correctly picked up when the core React Native repository runs ESLint, but if a community module uses this ESLint config then they will, by default, get the standard Prettier configuration. To fully match the React Native code style, they will need to include the same configuration in their repository.

I should say, this is all guesswork on my part, I've not actually tested that this is the case, however, from the Prettier and eslint-plugin-prettier documentation, that should be the case.

[elicwhite]

We could also duplicate the config into the eslint config and ensure that it stays consistent, right?

[cpojer]

Thanks so much, this is exactly what I had in mind to start.

• I agree we should figure out how to make all projects use the same prettier config, at least in react-native-community. Maybe in a follow-up PR we can add the config to the eslint setup (even if that's not recommended) and add a README to this package that asks people to add the appropriate prettier config for their projects.
• Did you ask the author of the npm package for the package name and are you able to publish to it? Otherwise I'll have to change the name prior to publishing (I may reuse the @react-native-community org).
• I'll try to land and see if I have to make any changes internally.

[facebook-github-bot]

@cpojer is landing this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[react-native-bot]

This pull request was successfully merged by @dratwas in e903d80.

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