Support overrides

When adding TypeScript support in eslint-config-kentcdodds (see https://github.com/kentcdodds/eslint-config-kentcdodds/pull/54), I noticed CI isn’t failing even though I haven’t added all @typescript-eslint rules (yet).

I’m happy to help out if you could point me into the right direction of adding support here. 🙂

[darekkay]

My workaround is to define high-level configurations (containing overrides) and move all plugin rules into separate files:

root
  - config-all.js
  - react.js
  - nodejs.js
  - plugins
    - base.js
    - jest.js
    - typescript.js

So while react.js uses overrides to apply typescript rules only to TS(X) files, there’s a special config file config-all.js that contains all rules without overrides:

module.exports = {
  extends: [
    "../plugins/base.js",
    "../plugins/jest.js",
    "../plugins/typescript.js",
  ],

  plugins: ["@typescript-eslint"],
};

When checking config-all.js, eslint-find-rules will now check all referenced plugins/rules.

[MichaelDeBoey]

A new use-case we have on eslint-config-kentcdodds is wanting to enable all Jest related rules only for testing files (as can be seen in https://github.com/kentcdodds/eslint-config-kentcdodds/pull/98).

Enabling all the rules in the root just to make our tests happy isn’t the preferred way, so this feature could benefit us a lot.

@leepowelldev Do you have the time to create a PR with working version of this or should we look into it ourselves?