Add string-content rule

[fisker]

fixes #327

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IssueHunt Summary

Referenced issues

This pull request has been submitted to:

• #327: Rule proposal: string-content

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[sindresorhus]

You're not waiting for feedback from me on anything here, right?

[fisker]

I'm not, but I have problem with this, harder than I thought. I'll explain later when I need your help.

[fisker]

@sindresorhus Set default to off, or we just disable this rule on our codebase?

I suggest set default to off.

[sindresorhus]

Yes, it should be off by default. I will enable it in XO with some useful patterns, but I think that's too opinionated for this general plugin.

[fisker]

@sindresorhus This PR is ready for review.

Something I need explain first, I set this rule only report one error a time on one string node, for the following reasons.

1. Case: String ab, replacement a -> A, b -> B

If we check all patterns on the original string, we will get two problem with 2 fixes, so we get fix ab -> Ab and ab -> aB, but they are conflict, so only b->B get replaced.

2. Case: String a, replacement a -> b, b -> c

If we check a -> b first, got result b, then check b -> c on b, got correct result c, we report two problems a -> b, b -> c, but there is no b in the original string.

3. If we consider some replacement set fix:false, this get even complicated.

Another thing, may need discuss, I run check on TemplateElement instead of TemplateLiteral, so const foo = `a${'a'}a${'a'}a` with a->b will got 3 error on TemplateElement and 2 error on Literal, I'm not sure is this a problem.

[sindresorhus]

If we check all patterns on the original string, we will get two problem with 2 fixes

You can give the report() method an array of fixes. Does that help?

An array which includes fixing objects. - https://eslint.org/docs/developer-guide/working-with-rules#applying-fixes

[fisker]

You can give the report() method an array of fixes. Does that help?

I've tried this before, not useful for this case.

[sindresorhus]

Alright. Let's at least document that it only reports one thing per node.

[sindresorhus]

@fisker I think there's only https://github.com/sindresorhus/eslint-plugin-unicorn/pull/496/files#r386895029 left and this is ready to be merged?

[fisker]

@sindresorhus I've add a simple description 9c0953d . Not sure what else you want add here. Maybe you can help, I'm really bad at docs .