feat: support ESLint 8.x

[MichaelDeBoey]

Superseded by #903

[G-Rath]

Thanks but I don't know when we'll be able to land this since we tend to match supported node versions with Jest, which still supports v10 and I'd like to avoid adding more long-living PRs to our already decent list.

[SimenB]

I'm fine making a breaking change dropping node 10 (and eslint 5 if needed)

[MichaelDeBoey]

@SimenB Since we have @typescript-eslint/experimental-utils as a dependency and it will drop support for Node v10 & ESLint v5, we don't really have a choice other than making these breaking changes.

I'm happy to re-open the PR.

[SimenB]

@MichaelDeBoey let's do it, lot's of other deps we can update at the same time 🙂 But let's start just by dropping eslint 5 and node 10 without adding pre-release @typescript-eslint/experimental-utils until it's properly out. That should just be a minor change at that point, right?

[MichaelDeBoey]

@SimenB Since @typescript-eslint/eslint-plugin is a peerDependency, this will be breaking whenever we update

BREAKING CHANGE: Requires Node@^12.22.0 || ^14.17.0 || >=16.0.0
BREAKING CHANGE: Requires ESLint@^6.0.0 || ^7.0.0 || ^8.0.0-0
BREAKING CHANGE: Requires @typescript-eslint/eslint-plugin@^5.0.0-0

[SimenB]

Not if we support both v4 and v5, right?

EDIT: I see the range is already >=4, so that should be fine already I believe (we should have a test run with v5 verifying it works, though, and it should probably be 4.x || ^5.0.0-0 or something)

[MichaelDeBoey]

@SimenB Running it with v5 will break peerDependency of @typescript-eslint/experimental-utils (which is in our dependencies and is still v4 for now).
Updating our @typescript-eslint/experimental-utils version to v5, will break our peerDependency then.

I see the range is already >=4,

That should actually be ^4.0.0 for the same reason mention just above the quote

[SimenB]

Why would it break? @typescript-eslint/eslint-plugin pulls in its own version of the utils, I don't think this plugin cares what version it is.

[MichaelDeBoey]

@SimenB @typescript-eslint/eslint-plugin has @typescript-eslint/parser as peerDependency though.

https://github.com/typescript-eslint/typescript-eslint/blob/4a88de2c621ae645c070d995768006df8cb7e4df/packages/eslint-plugin/package.json#L64-L67

[SimenB]

Right, but that only affects users of the plugin, not us (I think) as we don't pull in the plugin, the user does

[MichaelDeBoey]

It technically affects our users too since it's our peerDependency, no? 🤔

[SimenB]

For us it's an optional one, we don't care which one the user pulls in. Us supporting two versions with different peer deps of their own doesn't matter, the user just pulls in the correct versions they use

[SimenB]

Regardless, we can start by dropping node v10 and eslint v5 on a next branch, then dig more into whether or not adding eslint v8 and ts-eslint v5 to our matrix messes anything up

[SimenB]

next now exists without node 10 or 15 and without eslint 5: https://github.com/jest-community/eslint-plugin-jest/tree/next