Support ESLint v6

[sheepsteak]

The main issues are:

• Use require.resolve when passing the parser option to RuleTester (https://eslint.org/docs/user-guide/migrating-to-6.0.0#rule-tester-parser)
• Add ecmaVersion when sourceType is module (https://eslint.org/docs/user-guide/migrating-to-6.0.0#-the-default-parser-now-validates-options-more-strictly)
• Transform output of the FileEnumerator into what the import/no-unused-modules rule expects
• @typescript-eslint/parser is using an internal module (eslint/lib/util/traverser) which has been removed in ESLint@6 and therefore causing an error. It's been fixed in fix(parser): add simpleTraverse, replaces private ESLint util typescript-eslint/typescript-eslint#628 but not been released yet. (Updated to canary, thanks @golopot)
• Same as above for typescript-eslint-parser but this is an archived package. As I write this I realise I should probably use the testVersion function so that tests for this are skipped on eslint>=6

To test:

npm i eslint@6
npm test

The only failing tests should be related to the TypeScript issue above.

Related to airbnb/javascript#2036.
Fixes #1362.

[sheepsteak]

It's also having some sort of whitespace issue with a couple of tests as you can see here - https://ci.appveyor.com/project/benmosher/eslint-plugin-import/builds/25480510/job/i7a5k9x6j6s1hg8a#L3072. I think I've fixed it and then it comes back again haha

[coveralls]

Coverage remained the same at 97.803% when pulling c61fad0 on sheepsteak:eslint-6 into fc65509 on benmosher:master.

[coveralls]

Coverage remained the same at 97.803% when pulling c61fad0 on sheepsteak:eslint-6 into fc65509 on benmosher:master.

[coveralls]

Coverage increased (+0.1%) to 97.953% when pulling 7e41d29 on sheepsteak:eslint-6 into fc65509 on benmosher:master.

[coveralls]

Coverage remained the same at 97.803% when pulling c61fad0 on sheepsteak:eslint-6 into fc65509 on benmosher:master.

[coveralls]

Coverage remained the same at 97.803% when pulling c61fad0 on sheepsteak:eslint-6 into fc65509 on benmosher:master.

[coveralls]

Coverage remained the same at 97.803% when pulling c61fad0 on sheepsteak:eslint-6 into fc65509 on benmosher:master.

[ljharb]

It seems like you made a bunch of unrelated formatting changes; please revert them.

[ljharb]

Are you perhaps running prettier on autosave in your editor or something? If so, disable that - prettier should only be run via eslint autofix, and only on repos that use it.

[ljharb]

Suggested change

	return Array.from(e.iterateFiles(src), ({ filePath, ignored })=>({
	return Array.from(e.iterateFiles(src), ({ filePath, ignored }) => ({

[sheepsteak]

Sorry about the double quote changes. I've reverted all of them. I have Prettier set to only work when there is a .prettierrc present so I'm not sure what's causing that 🤷‍♂️

[golopot]

I suppose it is eslint in your editor doing that changes. The ci does not lint over ./tests, so there are many lines in ./tests not passing eslint.

[sheepsteak]

Added a commit to only run tests for typescript-eslint-parser when ESLint is <6 where appropriate given that it's archived and will probably never get the required fix.

Would you like me to update Travis CI config to use 6.0.0 instead of 6.0.0-alpha?

[ljharb]

Yes, please.

[ljharb]

LGTM pending a nit

[sheepsteak]

@ljharb OK I had to do one more thing and make testVersion take a function instead of an object so that require.resolve didn't get run and throw an error. This happens when trying to resolve the TypeScript parsers on test runs where they've been removed in dep-time-travel.sh. All tests pass on Travis now 🎉

[frederikhors]

Please @ljharb can you merge and release this? This is urgent now with eslint 6 in production everywhere (unfortunately).

"eslint": "2.x - 6.x"

[ljharb]

@frederikhors If npm ls exits nonzero, your dep graph is invalid, so eslint 6 shouldn't be in production when you have peer dep conflicts with it. If it's urgent for you, it's a problem of your own making.

[frederikhors]

@ljharb the problem is not mine but it is here: prettier/prettier-vscode#672

[ljharb]

Their problem is the same; upgrading to eslint v6 prior to peer deps upgrading is invalid.

[frederikhors]

@ljharb still same problem today.