Support eslint v9

[DamienCassou]

eslint 9 is being prepared and comes with a lot of changes impacting users and plugin developers: see https://eslint.org/blog/2023/12/eslint-v9.0.0-alpha.0-released/ for example.

What is the status of eslint v9 support for eslint-plugin-import?

[ljharb]

Since we don’t even support flat config yet (#2873), and eslint doesn’t provide any replacement for FileEnumerator, I’d say it’ll probably be awhile before we support eslint 9.

[JounQin]

At least we can support using eslintrc on eslint v9 currently.

TODO: compatible with some internal API migration like context vs SourceCode.

[ljharb]

I'd definitely love to add some tests on eslint 9, using the env var that restores eslintrc, so we can get ahead of any needed changes.

[TiagodePAlves]

I made a patch for eslint-plugin-import@2.29.1 (and eslint-plugin-i@2.29.1) that works with pnpm and ESLint v9.0.0-beta.2: https://gist.github.com/TiagodePAlves/8c9b1ed4062a484022f5ebf7ba53a5d5

[ljharb]

@TiagodePAlves thanks, that's helpful! once we have tests running on eslint 9, it shouldn't be too difficult to adapt that patch into something that works on both v9 and older versions.

[G-Rath]

@ljharb fwiw I did a very naive find-and-replace of the context utils we're using in eslint-plugin-jest and it looks like that's all thats needed? specifically also seems that only getSourceCode and getScope are the only two removed context methods being used (or at least out of the rules eslint-plugin-jest is using).

Would you like me to attempt a draft PR? I don't know if I'll have the bandwidth to setup a whole test suite but I figure I can contribute enough to kick start the work 🙂

[ljharb]

@G-Rath that might be the case! The blocker really is setting up tests, unfortunately - if we can get tests working on eslint 9, the rest is something I can probably find time for sooner than later :-)

[ryanblock]

@ljharb it may be something that's classified under "it'll take more time to explain than it would take for me [@ljharb] to do it" but if you can scope the test suite work here I or others may be able to help pitch in! 💕

[ljharb]

@ryanblock basically:

1. add eslint 9 to the test matrix
2. get tests passing on eslint 9

#2996 should cover this eventually. If anyone has contributions, please do NOT open a new PR, and instead, comment a link to the branch or commit on the PR, and the OP or myself can pull them in.