feat: support eslint@8

[SimenB]

@G-Rath this is not meant to be merged, just to see where we're at.

• I have to use resolutions for other usage of @typescript-eslint/experimental-utils as some use eslint internals
• typecheck fails
  
• src/rules/__tests__/unbound-method.test.ts fails, so that rule needs to be tweaked to work with v5 of @typescript-eslint/eslint-plugin v8 of eslint
• need to patch eslint-plugin-import until [New] no-unused-modules: add eslint v8 support import-js/eslint-plugin-import#2194 is released

Closes #903

[SimenB]

it uses package exports: jestjs/jest#9771

[G-Rath]

Sweet, I'll have a look at the type failings sometime this week - are we still planning to try and have backwards compat with v4?

[SimenB]

are we still planning to try and have backwards compat with v4?

Unless it proves painful, yes. I assume it's just a change of a few lines, but who knows 😀

[G-Rath]

Cool cool - unbound-method is really the only one I'm worried about right now, as the types should be easily handled worst-case with some raw strings and coverage ignores, but if unbound-method has had any major changes (in it or any utils that it uses) then it might be tough.

(I've not have a chance to look at what the actual changes in v5 are, as been pretty slammed with work)

[SimenB]

Seems v4 of the plugin doesn't support eslint v8, so we need to exclude that combination from CI. I still think it's worthwhile for us to attempt to support both versions, tho (even though they don't work together).

EDIT: hah, somehow managed the config first try 🥳

[SimenB]

Ok, the issue (beyond missing update to eslint-plugin-import) just seems to be that the unbound rule is broken on ESLint v8. Beyond that we're good to go (oh, and dependencies using @typescript-eslint/experimental-utils@4, but we can use resolutions for that to get a release out while we wait)

[G-Rath]

This was the issue with unbound-rule:

● Test suite failed to run

    Cannot find module 'eslint/use-at-your-own-risk' from 'node_modules/@typescript-eslint/eslint-plugin/dist/util/getESLintCoreRule.js'

    Require stack:
      node_modules/@typescript-eslint/eslint-plugin/dist/rules/brace-style.js
      node_modules/@typescript-eslint/eslint-plugin/dist/rules/index.js
      node_modules/@typescript-eslint/eslint-plugin/dist/index.js
      src/rules/__tests__/unbound-method.test.ts

      at Resolver.resolveModule (node_modules/jest-resolve/build/resolver.js:322:11)

[SimenB]

hah, that's it 😅 nice!

[SimenB]

we need to remove this at some point, but fine for now as it's repo local (like the moduleNameMapper thing)

[github-actions]

🎉 This PR is included in version 25.1.0 🎉

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