In Docs, "Configuration Based on Glob Patterns" should specify it's a v4.1 feature. Fails silently on earlier versions.

[geoffreyyip]

Tell us about your environment

• ESLint Version: 3.x
• Node Version: 7.x
• npm Version: 5.x

Problem:

I had a default configuration for my **/*.js files and I was trying to set linting rules differently for my **/*.test.js files. Mostly, I wanted to use describe, it, and other global testing variables in my testing files. I was trying to avoid messages like error 'describe' is not defined no-undef

On the Configuring ESLint's "Configuration Based on Glob Patterns" section, I found out I could specify glob-based overrides, and so I specified my configuration to something like this.

eslintrc.js

{
  "env": { "node": true },
  "overrides": [
    {
      "files": [ "**/*.test.js" ],
      "env": { "mocha": true }
    }
  ]
}

What did you expect to happen?

I expected my *.test.js files to be linted differently. I expected to get rid of the error 'describe' is not defined no-undef message. Instead, it persisted. And I had no idea why. I spent a hour checking my globs and configuration before realizing that I was still on v3.19.0 and the glob-based overrides were only added 2 days ago, according to #3611.

Once I upgraded to v4.1.0, the overrides syntax worked as normal.

Two things that could help future developers avoid my mistake:

• A note in the docs saying users should upgrade to v4.1.0 to use the glob-based configuration feature and that it will have no effect in earlier versions.
• A CLI warning for v3.x telling users that overrides syntax is unavailable for them.

[ilyavolodin]

That's a good point, although we've never done that for other global features. Not sure how to best handle this. Also, we don't normally make changes in older versions of ESLint.

[geoffreyyip]

Vue.js docs handles this pretty nicely.

It could be a good practice going forward. eslint has a crazy amount of configurations, feature, and partner libraries. It's not always easy to pinpoint the bug.

Thanks for hearing me out!

[JakobJingleheimer]

I'm experiencing this on v4.18.2

"overrides": [
  {
    "env": {
      "mocha": true,
    },
    "files": [
      "**/*.spec.js"
    ],
    "rules": {
      "func-names": "off",
      "no-unused-expressions": "off",
      "prefer-arrow-callback": [
        "error",
        "never"
      ]
    }
  }
],

Nothing from this override block is getting applied to my spec files.

[platinumazure]

@jshado1 Please open a new issue, thanks!

[JakobJingleheimer]

@platinumazure #10136

[nzakas]

It seems simple enough to add this note in the docs. I'll add it.