"ESLint couldn't find the plugin" notice loses a last character

[JoshuaKGoldberg]

Tell us about your environment

• ESLint Version: 6.8.0
• Node Version: 12.0.0
• npm Version: 6.14.4

What parser (default, Babel-ESLint, etc.) are you using?

Not relevant, but "@typescript-eslint/parser"

Please show your full configuration:

Configuration

module.exports = {
  extends: [
    "plugin:eslint-config-prettier",
  ],
};

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

eslint --print-config ./eslintrc.js

What did you expect to happen?

The module name being reported as not existing should be ... eslint-config-prettier, I'm guessing?

What actually happened? Please include the actual, raw output from ESLint.

Oops! Something went wrong! :(

ESLint: 6.8.0.

ESLint couldn't find the plugin "eslint-plugin-eslint-config-prettie".

(The package "eslint-plugin-eslint-config-prettie" was not found when loaded as a Node module from the directory "C:\Code\tslinttest".)

It's likely that the plugin isn't installed correctly. Try reinstalling by running the following:

    npm install eslint-plugin-eslint-config-prettie@latest --save-dev

The plugin "eslint-plugin-eslint-config-prettie" was referenced from the config file in ".eslintrc.js".

If you still can't figure out the problem, please stop by https://gitter.im/eslint/eslint to chat with the team.

This issue split from: typescript-eslint/tslint-to-eslint-config#439.

Are you willing to submit a pull request to fix this bug?

I'd love to! 🤗

[yeonjuan]

Hi @JoshuaKGoldberg :) Thanks for the reporting. 😀

It seems a bug to me; I agree that the error message should be improved

The module name being reported as not existing should be ... eslint-config-prettier, I'm guessing?

Maybe not, 🤔 because the actual reason is incorrect configuration.

"plugin:eslint-config-prettier",

The "plugin:xxx" means the use of exported configuration from other plugins.
so it should be consists of "plugin:" + {package name} + "/" + {configuration name}

• Using the configuration from a plugin

The extends property value can consist of:

• plugin:
• the package name (from which you can omit the prefix, for example, react)
• /
• the configuration name (for example, recommended)

---

eslint/lib/cli-engine/config-array-factory.js

Line 804 in 015edf6

const slashIndex = extendName.lastIndexOf("/");

the problem is here. there is no '/' character in extendName so lastIndexOf return -1;

[Vovch]

Hi, everyone!

Stumbled upon this issue in other person's code yesterday.

As a solution I might propose adding the next code:

if (slashIndex === -1) {
    const wrongConfigName = JSON.stringify(extendName).slice(1, -1);
    throw new Error(`'extends' requires a configuration name for '${wrongConfigName}', provided after '/' sign.`);
}

This way it is possible to also give an understandable error in some cases when the user mistakenly prints \ sign. E.g.:
Error: 'extends' requires a configuration name for 'plugin:prettier\recommended', provided after '/' sign.

instead of:
ecommende". because there is whitespace in the name. Please check your configuration and remove all whitespace from the plugin name.

[mysticatea]

Thank you for your report.

But it's not a bug. The plugin: specifier needs a plugin name and a config name: plugin:foo/bar. Here, the foo is a plugin name, it means loading eslint-plugin-foo, and the bar is a config name, it means using the require("eslint-plugin-foo").configs.foo config object.

A PR is welcome in order to print understandable error message in that case.

[jaganathanb]

I faced same kind of issue but for @typescript-eslint/eslint-plugin. The surprising thing is that the issue is because of eslint-nullish-coalescing which changed the content of node_modules\.bin\eslint.cmd file to some thing like below.

@IF EXIST "%~dp0\node.exe" (
  "%~dp0\node.exe"  "%~dp0\..\eslint-nullish-coalescing\bin\eslint.js" %*
) ELSE (
  @SETLOCAL
  @SET PATHEXT=%PATHEXT:;.JS;=;%
  node  "%~dp0\..\eslint-nullish-coalescing\bin\eslint.js" %*
)

I installed eslint version 7 but the error message was showing up as 4.19.1 which the eslint-nullish-coalescing package version which is a fork of eslint.

Please check your eslint.cmd file's content.

Here is the stackoverflow post.

[cellog]

this is working as intende? That seems like a bad desig. Tell people they used invalid syntax, don't just chop off the last characte.

[eslint-deprecated]

Unfortunately, it looks like there wasn't enough interest from the team
or community to implement this change. While we wish we'd be able to
accommodate everyone's requests, we do need to prioritize. We've found
that issues failing to reach accepted status after 21 days tend to
never be accepted, and as such, we close those issues.
This doesn't mean the idea isn't interesting or useful, just that it's
not something the team can commit to.

Thanks for contributing to ESLint and we appreciate your understanding.

[mdjermanovic]

PR to print an appropriate error message in this case: #13473

[mdjermanovic]

Fixed by #13473.