Support ESLint 8.x

[MichaelDeBoey]

ESLint v8.0.0 is released 🎉

It would be awesome to have official ESLint 8 support. 👊
I'm happy to help where I can of course 🙂

[G-Rath]

Thanks, I've got a branch locally covering this but we need @typescript-eslint to support v8 before we'll be able to properly look at supporting.

[zdm]

@typescript updated to the version 5 and supports eslint 8 now.

[SimenB]

Yeah, we released an update a couple of hours ago: https://github.com/jest-community/eslint-plugin-jest/releases/tag/v25.0.4

Cannot test against eslint@8 for some reason, but I think consumers should be unblocked

[EvHaus]

I'm getting this error when trying to use eslint-plugin-jest@25.0.4 with eslint@8.0.0:

TypeError: Failed to load plugin 'jest' declared in '.eslintrc.js': Class extends value undefined is not a constructor or null

UPDATE: This problem went away for us after installing the latest eslint-plugin-jest@25.2.2

[zdm]

In v25.0.5 you forget to update peer deps:

"peerDependencies": {
    "@typescript-eslint/eslint-plugin": "^4.0.0 || ^5.0.0",
    "eslint": "^6.0.0 || ^7.0.0"
  },

I am unable to install it, because it conflicts with the @typescript, which is requires eslint 8.
Please, add ^8.0.0 to allowed eslint versions.

[SimenB]

@EvHaus huh, unexpected... I'm also unable to reproduce in a fresh repo doing yarn add eslint eslint-plugin-jest

// package.json
{
  "name": "eslint-8",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "devDependencies": {
    "eslint": "^8.0.0",
    "eslint-plugin-jest": "^25.0.5"
  }
}

// .eslintrc
{"plugins": ["jest"], "rules": {"jest/expect-expect": "error"}}

// test.js
test('dummy', function() {
  // no expect here
})

[SimenB]

@zdm no, we're unable to test against it. You can ignore the peer dep warning if you want, but seeing as this issue is still open support isn't officially released yet 🙂

[zdm]

It is not warning, npd dies with error.

npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! While resolving: @softvisio/cli@3.17.2
npm ERR! Found: eslint@8.0.0
npm ERR! node_modules/eslint
npm ERR!   eslint@"^8.0.0" from the root project
npm ERR!   peer eslint@"^6.0.0 || ^7.0.0 || ^8.0.0" from @typescript-eslint/eslint-plugin@5.0.0
npm ERR!   node_modules/@typescript-eslint/eslint-plugin
npm ERR!     @typescript-eslint/eslint-plugin@"^5.0.0" from the root project
npm ERR!     peerOptional @typescript-eslint/eslint-plugin@"^4.0.0 || ^5.0.0" from eslint-plugin-jest@25.0.5
npm ERR!     node_modules/eslint-plugin-jest
npm ERR!       eslint-plugin-jest@"^25.0.5" from the root project
npm ERR!   1 more (@typescript-eslint/parser)
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer eslint@"^6.0.0 || ^7.0.0" from eslint-plugin-jest@25.0.5
npm ERR! node_modules/eslint-plugin-jest
npm ERR!   eslint-plugin-jest@"^25.0.5" from the root project
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR!
npm ERR! See C:\Users\zdm\.n

[SimenB]

npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.

there's your workaround. It's just a warning. If that's not acceptable, you can wait until this issue is closed

[chrisfosterelli]

If it helps, we also got the same error as @EvHaus during a dependabot upgrade prompt for eslint 8. I assumed the issue was that we just needed to update eslint-plugin-jest for compatibility, but then got the peer dependency mismatch error @zdm indicated.

The legacy peer dep resolution is no longer the default for (presumably) good reasons and that flag enables it for one's whole app -- so we'll probably wait to see the peer dependency list updated.

[SimenB]

https://github.com/jest-community/eslint-plugin-jest/releases/tag/v25.1.0

[offich]

still getting the same error as this one. can anyone help?
#881 (comment)

[SimenB]

Please open up a separate issue with a reproduction

[basitsattar]

still getting the same error as this one. can anyone help? #881 (comment)

Did you find any solution? facing the same issue

[SimenB]

Just open up a new issue with a reproduction. I assume you'll find your error while reducing your own project down to a reproduction, but if not I'm happy to fix it