ESLint Plugin Evelyn

ESLint plugin for my projects with my preferred code style

Description

These are my configs and code related to maintaining ESLint scripts.

My code style is very opinionated, so I only use this package on my projects. However, others are welcome to use, copy, or fork this project.

Installation

Save this project to your dev dependencies. If you are using an version on npm older than v7.0.0, you will have to install peer dependencies manually.

npm install --save-dev eslint-plugin-evelyn

Peer Dependencies

npm may warn about any missing peer dependencies when installing this plugin.

npm WARN eslint-plugin-evelyn@x.x.x requires a peer of eslint-plugin-xxxxx@^x.x.x but none is installed. You must install peer dependencies yourself.

If you are using and loading a config that requires one of the mentioned dependencies, add the plugin as a dev dependency that satisfies the specified version range. Otherwise, you can safely ignore these messages.

ESLint always resolves and loads plugins when the configs are extended in the top-level config, but only resolves plugins in an override once a file matches its glob pattern.

Usage

Include as many configs as you'd like to use in your config. Extend them in the order that they should be applied, in order of importance, lowest to highest.

Configs Applied to All Files

.eslintrc

{
    "plugins": [
        "evelyn"
    ],

    "extends": [
        "plugin:evelyn/default",
        "plugin:evelyn/node"
    ]
}

Configs applied to a specific path

Requires eslint >=6.0.0.

.eslintrc

{
    "plugins": [
        "evelyn"
    ],

    "extends": [
        "plugin:evelyn/default"
    ],

    "overrides": [
        {
            "files": [
                "src/**/*.js"
            ],
            "extends": [
                "plugin:evelyn/node"
            ]
        }
    ]
}

TypeScript React App Example

.eslintrc.js

module.exports = {
	"plugins": [
		"@evelyn",
	],

	"extends": [
		"plugin:@evelyn/default",
		"plugin:@evelyn/node",
		"plugin:@evelyn/react",
		"plugin:@evelyn/typescript",
	],

	"ignorePatterns": [
		"build",
		"coverage",
	],

	"overrides": [
		{
			"files": [
				"**/*.test.{ts,tsx}",
				"**/__tests__/**/*.{ts,tsx}",
			],
			"extends": [
				"plugin:@evelyn/jest",
				"plugin:@evelyn/testing-library-react",
			],
		},
	],
};

package.json (snippet)

Make sure to remove any references to old ESLint plugins or configs and replace the lint script with eslint ./.

{
  "name": "my-app",
  "...": "...",
  "scripts": {
    "...": "...",
    "lint": "eslint ./"
  }
}

Testing

# Install dependencies
npm install
# Symlink itself into node_modules for ESLint
# As of eslint-plugin-evelyn v3.0.0, this is done fully automatically
npm run link

# Run all tests!
npm run test

Final Config Array Tests

final-config-array.eslintrc.js tests to make sure all modules and configs load properly. Without this test, if a parser or plugin doesn't load and is never used to lint a file, ESLint won't report the error.

Linting

This plugin uses itself to lint so we must make sure the working copy of eslint-plugin-evelyn is in node_modules. Only ESLint should require it from there.

# Install dependencies
npm install
# Symlink itself into node_modules for ESLint
# As of eslint-plugin-evelyn v3.0.0, this is done fully automatically
npm run link

# Run lint!
npm run lint

Debugging

• Make sure you're using the local version of eslint using npm run or npx eslint
• Use the --debug ESLint CLI flag for determining things like the modules that get loaded
• Use the --print-config ESLint CLI flag for a minimal computed config

Saving the Entire Computed Config Array

Run the default export from the save-config.js file from inside the config file to output to monkey-patch ESLint. This works on this project as well as any package that has eslint-plugin-evelyn >=1.0.0 as a dependency.

.eslintrc.js

require("eslint-plugin-evelyn/lib/util/save-config")();


// The rest of your config file
// [...]

This saves the config array that is usually partially outputted to the console during execution with the --debug flag.

$ npx eslint --debug
# [...]
eslint:cascading-config-array-factory Configuration was determined: ConfigArray [...]

Recording Changes to the Final Config Array

record-changes.eslintrc.js saves the final config array to record-changes.json with paths removed.

The script is used to track the changes to the final array over time using the pre-commit git hook. This is helpful in reviewing pull requests.

---

Configs

See the peerDependencies in package.json for recommended dependency version ranges.

Name	Peer Dependencies
babel	@babel/eslint-parser
default	eslint-plugin-unicorn, eslint-plugin-import, eslint-plugin-regexp
esm	eslint-plugin-unicorn, eslint-plugin-import
jest	eslint-plugin-node, eslint-plugin-jest
jsx	eslint-plugin-jsx-a11y
mocha	eslint-plugin-node, eslint-plugin-mocha
node	eslint-plugin-node
react	eslint-plugin-react, eslint-plugin-jsx-a11y, eslint-plugin-react-hooks, eslint-plugin-import
testing-library	eslint-plugin-testing-library
testing-library-react	eslint-plugin-testing-library
typescript	@typescript-eslint/eslint-plugin, @typescript-eslint/parser, typescript, eslint-plugin-import, eslint-import-resolver-typescript

---

Semantic Versioning Policy

This plugin follows semantic versioning a-la-ESLint.

• Patch release (not intended to break your lint build)
  • A bug fix in a rule that results in ESLint reporting fewer or the same amount of errors
  • Improvements to documentation
  • Non-user-facing changes such as refactoring code
  • Re-releasing after a failed release
• Minor release (might break your lint build)
  • A new config or rule is added
  • A new non-default option is added to an existing rule
  • A bug fix in a rule that results in ESLint reporting more errors
  • An existing rule, config, or part of the public API is deprecated, but still runs/works
  • New capabilities to the public API are added
  • A config is updated in a way that results in ESLint fewer or the same amount of errors
    • The hypothetical removal of semi would be a good example as not enforcing it could create the potential to break your code
• Major release (likely to break your lint build)
  • A config or rule is removed
  • A config is updated in a way that results in ESLint reporting more errors
  • A newer version of ESLint, a plugin, or Node.js may be required
    • Any changes to the low end of any of the peerDependencies or the engines
  • A rule's default behavior is changed
  • Part of the public API is removed or changed in an incompatible way

License

Copyright Evelyn Hathaway, MIT License