Packages: Reimplement ESLint config as plugin (#12763)

* Packages: Move eslint-config to eslint-plugin

(Fails pre-commit, but in effort to ensure history preservation)

* eslint-plugin: Add npmrc to avoid package-lock.json

* Framework: Update path references for eslint-config to -plugin

* eslint-plugin: Reimplement ESLint config as plugin

* eslint-plugin: Unmark as private

* eslint-plugin: Undocument custom ruleset

.eslintrc.js

@@ -19,7 +19,7 @@ const majorMinorRegExp = escapeRegExp( version.replace( /\.\d+$/, '' ) ) + '(\\.
 module.exports = {
 	root: true,
 	extends: [
-		'@wordpress/eslint-config',
+		'plugin:@wordpress/eslint-plugin/recommended',
 		'plugin:jest/recommended',
 	],
 	rules: {

docs/manifest.json

@@ -498,9 +498,9 @@
 		"parent": "packages"
 	},
 	{
-		"title": "@wordpress/eslint-config",
-		"slug": "packages-eslint-config",
-		"markdown_source": "https://raw.githubusercontent.com/WordPress/gutenberg/master/packages/eslint-config/README.md",
+		"title": "@wordpress/eslint-plugin",
+		"slug": "packages-eslint-plugin",
+		"markdown_source": "https://raw.githubusercontent.com/WordPress/gutenberg/master/packages/eslint-plugin/README.md",
 		"parent": "packages"
 	},
 	{

package.json

@@ -60,7 +60,7 @@
 		"@wordpress/babel-preset-default": "file:packages/babel-preset-default",
 		"@wordpress/browserslist-config": "file:packages/browserslist-config",
 		"@wordpress/custom-templated-path-webpack-plugin": "file:packages/custom-templated-path-webpack-plugin",
-		"@wordpress/eslint-config": "file:packages/eslint-config",
+		"@wordpress/eslint-plugin": "file:packages/eslint-plugin",
 		"@wordpress/jest-console": "file:packages/jest-console",
 		"@wordpress/jest-preset-default": "file:packages/jest-preset-default",
 		"@wordpress/library-export-default-webpack-plugin": "file:packages/library-export-default-webpack-plugin",

packages/eslint-plugin/.npmrc

@@ -0,0 +1 @@
+package-lock=false

packages/eslint-plugin/README.md

@@ -0,0 +1,48 @@
+# ESLint Plugin
+
+[ESLint](https://eslint.org/) plugin including configurations and custom rules for WordPress development.
+
+## Installation
+
+Install the module
+
+```bash
+npm install @wordpress/eslint-plugin --save-dev
+```
+
+### Usage
+
+To opt-in to the default configuration, extend your own project's `.eslintrc` file:
+
+```json
+{
+	"extends": [ "plugin:@wordpress/eslint-plugin/recommended" ]
+}
+```
+
+Refer to the [ESLint documentation on Shareable Configs](http://eslint.org/docs/developer-guide/shareable-configs) for more information.
+
+The `recommended` preset will include rules governing an ES2015+ environment, and includes rules from the [`eslint-plugin-jsx-a11y`](https://github.com/evcohen/eslint-plugin-jsx-a11y) and [`eslint-plugin-react`](https://github.com/yannickcr/eslint-plugin-react) projects.
+
+#### Rulesets
+
+Alternatively, you can opt-in to only the more granular rulesets offered by the plugin. These include:
+
+- `es5`
+- `esnext`
+- `jsx-a11y`
+- `react`
+
+For example, if your project does not use React, you could consider extending including only the ESNext rules in your project using the following `extends` definition:
+
+```json
+{
+	"extends": [ "plugin:@wordpress/eslint-plugin/esnext" ]
+}
+```
+
+These rules can be used additively, so you could extend both `esnext` and `custom` rulesets, but omit the `react` and `jsx-a11y` configurations.
+
+The granular rulesets will not define any environment globals. As such, if they are required for your project, you will need to define them yourself.
+
+<br/><br/><p align="center"><img src="https://s.w.org/style/images/codeispoetry.png?1" alt="Code is Poetry." /></p>

packages/eslint-plugin/configs/custom.js

@@ -0,0 +1,19 @@
+module.exports = {
+	rules: {
+		'no-restricted-syntax': [
+			'error',
+			{
+				selector: 'CallExpression[callee.name=/^__|_n|_x$/]:not([arguments.0.type=/^Literal|BinaryExpression$/])',
+				message: 'Translate function arguments must be string literals.',
+			},
+			{
+				selector: 'CallExpression[callee.name=/^_n|_x$/]:not([arguments.1.type=/^Literal|BinaryExpression$/])',
+				message: 'Translate function arguments must be string literals.',
+			},
+			{
+				selector: 'CallExpression[callee.name=_nx]:not([arguments.2.type=/^Literal|BinaryExpression$/])',
+				message: 'Translate function arguments must be string literals.',
+			},
+		],
+	},
+};