ESLint v8 (#35576)

[simonhammes]

Description

Closes #35576.

@wordpress/eslint-plugin

• Updated packages for compatibility with ESLint v8

@wordpress/scripts

• Updated ESLint to v8 ([@wordpress/eslint-plugin] Support for ESlint v8 #35576)
  Changelog: https://eslint.org/docs/user-guide/migrating-to-8.0.0

How has this been tested?

• npm run lint
  The parsing errors will most likely be gone once Babel Preset: Update Babel packages to 7.16 version #36244 is merged (the optional Babel plugin was enabled by default since 7.14, see Archive @babel/plugin-syntax-class-properties babel/babel#13232)

I only just noticed that @gziolo was working on this, so some changes in this PR overlap with changes in #36244.

I will also add changelog entries before this gets merged.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[gziolo]

Thank you for starting this PR.

I only just noticed that @gziolo was working on this, so some changes in this PR overlap with changes in #36244.

I expect this PR will land this week. I will let you know when it happens so you could rebase this one.

[gziolo]

This is looking good. We still need to document all the major version updates for packages as breaking changes. We have some fixes included in this PR which confirm that upgrade for the new version of the @wordpress/eslint-plugin won't be seamless.

Let's see which errors will still require some action after merging changes for Babel v7.16.0.

[simonhammes]

This is looking good. We still need to document all the major version updates for packages as breaking changes.

I will document those changes 👍

[gziolo]

I landed #36244. Let’s see if rebasing is going to be enough to make all Continues Integration checks pass.

[simonhammes]

I landed #36244. Let’s see if rebasing is going to be enough to make all Continues Integration checks pass.

I rebased this PR.
Unfortunately, all eslint-plugin tests are still failing: https://github.com/WordPress/gutenberg/runs/4180615328?check_suite_focus=true#step:5:908

I tried to debug the issue and they might be related to the following issues/PRs:

• Same error message: Feature request: Support snapshot testing eslint/eslint#14936 (comment)
• Fix: add universal export to root eslint/eslintrc#57 => Upgrade: @eslint/eslintrc@1.0.3 for Jest workaround eslint/eslint#15164

It seems like the testing failures arise from an interaction between Jest & the upgrade from ESLint from v7 to v8.

I suspect that the following PR made to ESLint is the main culprit: eslint/eslint#14706 (since Jest does not seem to support the exports field in package.json: jestjs/jest#9771).

I could get the tests for the eslint-plugin to pass locally by adding an /** @jest-environment node */ annotation (to force Jest to use the node environment instead of the default jsdom environment) to the top of each test file in the packages/eslint-plugin/rules/__tests__ directory and running the tests directly with Jest (command: node node_modules/.bin/jest packages/eslint-plugin/). But this is not a real solution.

I also tried to upgrade ESLint to v8 on this branch: #33287 to eliminate the possibility of a possible incompatibility between ESLint v8 and Jest v26, but the tests also failed with the same error message as in the linked CI run at the top of this comment.

[gziolo]

It looks like there are some incompatible changes introduced between ESLint v8 and Jest v27 that will force us to update both tools at a similar time. I also encountered several issues when trying to upgrade Jest to v27, but I managed to resolve most of them. The only blocker is related to React Native so we need to wait until the Mobile team brings React Native to the more recent version. Do you think we will have to wait until Jest v27 is there before we can upgrade ESLint to v8?

[simonhammes]

@gziolo I managed to solve the issue with the failing unit tests.

However, the "Static Analysis" job is failing because of an uncommitted change to package-lock.json.

The job was failing earlier, then I ran npm install locally and committed the change: 920598e

Now the job is failing with the exact same opposite diff.

[gziolo]

I managed to solve the issue with the failing unit tests.

Great news! 🎉 Awesome work 👏

The job was failing earlier, then I ran npm install locally and committed the change: 920598e

Yes, I’m seeing it a lot recently. We really need to upgrade to npm 8 once the next major WordPress release (5.9 is scheduled for January) is out.

I think you can manually revert the changes in the lock file that get reported in the CI job.

[gziolo]

I guess we can land this PR pretty soon once the remaing issues/questions get addressed.

[gziolo]

Great work with the ESLint upgrade. Everything looks good, and it seems to work correctly. Let’s land it as soon as Continuous Integration turns green.

[gziolo]

It's now available for testing on npm with:

npm install --save-dev @wordpress/eslint-plugin@next

or

npm install --save-dev @wordpress/scripts@next

The stable version should be available in the second half of January.