Introduce lint base to make lint preset creation much easier (#41)

docs/SUMMARY.md

@@ -16,6 +16,7 @@
   * [Simple](/customization/simple.md)
   * [Advanced](/customization/advanced.md)
 * [Creating presets](/creating-presets.md)
+  * [Creating linting presets](/presets/neutrino-lint-base/README.md)
 * [Learning Resources](/learning-resources.md)
 * [API](/api/README.md)
 * [CLI](/cli/README.md)

docs/presets/neutrino-lint-base/README.md

@@ -0,0 +1,179 @@
+# Neutrino Lint Base
+[![NPM version][npm-image]][npm-url] [![NPM downloads][npm-downloads]][npm-url] [![Join Slack][slack-image]][slack-url]
+
+`neutrino-lint-base` is an abstract Neutrino preset base that makes creating ESLint-based presets simpler. By creating
+a linting preset that extends from `neutrino-lint-base`, the development overhead and dependencies needed can be
+significantly reduced. Use it as a baseline to create your own linting presets easier and more quickly.
+
+## Features
+
+- Quickly and easily create your own Neutrino linting presets
+- Modern Babel knowledge supporting ES modules, JSX (when used with React preset), Web and Node.js apps
+- Highly visible during development, fails compilation when building for production
+- Easily extensible to customize your project as needed
+
+## Development Requirements
+
+- Node.js v6.9+
+- Yarn or npm client
+- Neutrino v4
+
+## Installation
+
+`neutrino-lint-base` can be installed via the Yarn or npm clients.
+
+#### Yarn
+
+```bash
+❯ yarn add neutrino-lint-base
+```
+
+#### npm
+
+```bash
+❯ npm install --save neutrino-lint-base
+```
+
+Your project should also install any dependencies needed to operate based on options passed to `eslint-loader` or
+ESLint's CLIEngine.
+
+## Project Layout
+
+`neutrino-lint-base` follows the standard [project layout](/project-layout.md) specified by Neutrino. This
+means that by default all project source code should live in a directory named `src` in the root of the
+project. The `.js` or `.jsx` files in this directory are the ones that will be linted by your preset.
+
+## Creating the preset
+
+Your preset will follow the same guidelines for normally creating Neutrino presets, with your preset extending
+`neutrino-lint-base`. This starts out by having your package module export a function which accepts a Neutrino instance:
+
+```js
+module.exports = neutrino => {
+  // ...
+};
+```
+
+The next step is to `require`, or `import` if your package supports it, `neutrino-lint-base` and execute it with
+Neutrino. This will add the lint base's configuration to Neutrino for your preset to extend further:
+
+```js
+const lint = require('neutrino-lint-base');
+
+module.exports = neutrino => {
+  lint(neutrino);
+  // ...
+};
+```
+
+Now comes the core of your own preset. By extending from `neutrino-lint-base`'s "lint" rule and "eslint" loader, you
+can manipulate the options as you desire. Consider using a package such as
+[`deepmerge`](https://www.npmjs.com/package/deepmerge) to make extending these options easier:
+
+_Example: Create a preset that shuts off semicolons from being required by ESLint._
+
+```js
+const lint = require('neutrino-lint-base');
+const merge = require('deepmerge');
+
+module.exports = neutrino => {
+  lint(neutrino);
+  neutrino.config
+    .rule('lint')
+    .loader('eslint', props => merge(props, {
+      options: {
+        rules: {
+          semi: 'off'
+        }
+      }
+    }));
+};
+```
+
+_Example: Create a preset that lints a project using the Airbnb base ESLint rules._
+
+```js
+const lint = require('neutrino-lint-base');
+const merge = require('deepmerge');
+
+module.exports = neutrino => {
+  lint(neutrino);
+  neutrino.config
+    .rule('lint')
+    .loader('eslint', props => merge(props, {
+      options: {
+        baseConfig: {
+          extends: ['airbnb-base']
+        }
+      }
+    }));
+};
+```
+
+Visit the [creating presets](/creating-presets.md) documentation for more detailed information on creating your own
+custom preset.
+
+## Customization
+
+`neutrino-lint-base` creates some conventions to make overriding the configuration easier once you are ready to
+make changes.
+
+### Rules
+
+The following is a list of rules and their identifiers which can be overridden:
+
+- `lint`: Lints JS and JSX files from the `src` directory using ESLint. Contains a single loader named `eslint`.
+
+## Information
+
+The lint base will show errors and warnings in the console during development, and will cause a failure when
+creating a build bundle.
+
+---
+
+If you want your preset to also extend from another ESLint configuration that you have made a dependency, you must use
+`baseConfig.extends` rather than just `extends`. This is a limitation of ESLint, not this lint base.
+
+```js
+const lint = require('neutrino-lint-base');
+const merge = require('deepmerge');
+
+module.exports = neutrino => {
+  lint(neutrino);
+  neutrino.config
+    .rule('lint')
+    .loader('eslint', props => merge(props, {
+      options: {
+        baseConfig: {
+          extends: [
+            'YOUR_ESLINT_CONFIGURATION_BASE_A',
+            'YOUR_ESLINT_CONFIGURATION_BASE_B'
+          ]
+        }
+      }
+    }));
+};
+```
+
+---
+
+The linting base only configures a target environment for `es6`, leaving other build presets free to add their own
+target environments. If your preset puts restrictions on which environments it is capable of running, please document
+that clearly in your preset.
+
+For specifics on what options are configured when using this linting base, please
+[view the source](https://github.com/mozilla-neutrino/neutrino-dev/blob/master/packages/neutrino-lint-base/src/index.js).
+
+---
+
+## Contributing
+
+This preset is part of the [neutrino-dev](https://github.com/mozilla-neutrino/neutrino-dev) repository, a monorepo
+containing all resources for developing Neutrino and its core presets. Follow the
+[contributing guide](/contributing/README.md) for details.
+
+[npm-image]: https://img.shields.io/npm/v/neutrino-lint-base.svg
+[npm-downloads]: https://img.shields.io/npm/dt/neutrino-lint-base.svg
+[npm-url]: https://npmjs.org/package/neutrino-lint-base
+[slack-image]: https://neutrino-slack.herokuapp.com/badge.svg
+[slack-url]: https://neutrino-slack.herokuapp.com/

packages/neutrino-lint-base/README.md

@@ -0,0 +1,17 @@
+# Neutrino Lint Base
+[![NPM version][npm-image]][npm-url] [![NPM downloads][npm-downloads]][npm-url] [![Join Slack][slack-image]][slack-url]
+
+`neutrino-lint-base` is an abstract Neutrino preset base that makes creating ESLint-based presets simpler. By creating
+a linting preset that extends from `neutrino-lint-base`, the development overhead and dependencies needed can be
+significantly reduced. Use it as a baseline to create your own linting presets easier and more quickly.
+
+## Documentation
+
+See the [Neutrino docs](https://neutrino.js.org/presets/neutrino-lint-base/)
+for details on installation, getting started, usage, and customizing.
+
+[npm-image]: https://img.shields.io/npm/v/neutrino-lint-base.svg
+[npm-downloads]: https://img.shields.io/npm/dt/neutrino-lint-base.svg
+[npm-url]: https://npmjs.org/package/neutrino-lint-base
+[slack-image]: https://neutrino-slack.herokuapp.com/badge.svg
+[slack-url]: https://neutrino-slack.herokuapp.com/

packages/neutrino-lint-base/package.json

@@ -0,0 +1,26 @@
+{
+  "name": "neutrino-lint-base",
+  "version": "4.0.1",
+  "description": "Neutrino preset starter for adding building ESLint-based presets",
+  "main": "src/index.js",
+  "keywords": [
+    "neutrino",
+    "neutrino-preset",
+    "eslint"
+  ],
+  "author": "Eli Perelman <eli@eliperelman.com>",
+  "license": "MPL-2.0",
+  "repository": "mozilla-neutrino/neutrino-dev",
+  "dependencies": {
+    "babel-eslint": "^7.1.1",
+    "eslint": "^3.14.1",
+    "eslint-loader": "^1.6.1",
+    "eslint-plugin-babel": "^4.0.1",
+    "eslint-plugin-import": "^2.2.0"
+  },
+  "peerDependencies": {
+    "neutrino": "^4.0.0"
+  },
+  "homepage": "https://neutrino.js.org",
+  "bugs": "https://github.com/mozilla-neutrino/neutrino-dev/issues"
+}

packages/neutrino-lint-base/src/index.js

@@ -0,0 +1,40 @@
+const path = require('path');
+
+const MODULES = path.join(__dirname, '../node_modules');
+const IF_NOT_DEV =  process.env.NODE_ENV !== 'development';
+
+module.exports = ({ config }) => {
+  config
+    .module
+      .rule('lint')
+        .test(/\.(js|jsx)$/)
+        .pre()
+        .include(path.join(process.cwd(), 'src'))
+        .loader('eslint', require.resolve('eslint-loader'), {
+          failOnError: IF_NOT_DEV,
+          emitWarning: IF_NOT_DEV,
+          emitError: IF_NOT_DEV,
+          cwd: process.cwd(),
+          useEslintrc: false,
+          root: true,
+          plugins: ['babel'],
+          baseConfig: {},
+          envs: ['es6'],
+          parser: 'babel-eslint',
+          parserOptions: {
+            ecmaVersion: 2017,
+            sourceType: 'module',
+            ecmaFeatures: {
+              objectLiteralDuplicateProperties: false,
+              generators: true,
+              impliedStrict: true
+            }
+          },
+          settings: {},
+          globals: ['process'],
+          rules: {}
+        });
+
+  config.resolve.modules.add(MODULES);
+  config.resolveLoader.modules.add(MODULES);
+};

packages/neutrino-preset-airbnb-base/package.json

@@ -13,12 +13,9 @@
   "license": "MPL-2.0",
   "repository": "mozilla-neutrino/neutrino-dev",
   "dependencies": {
-    "babel-eslint": "^7.1.1",
+    "deepmerge": "^1.3.2",
-    "eslint": "^3.14.1",
     "eslint-config-airbnb-base": "^11.1.0",
-    "eslint-loader": "^1.6.1",
+    "neutrino-lint-base": "4.0.1"
-    "eslint-plugin-babel": "^4.0.1",
-    "eslint-plugin-import": "^2.2.0"
   },
   "peerDependencies": {
     "neutrino": "^4.0.0"

packages/neutrino-preset-airbnb-base/src/index.js

@@ -1,40 +1,15 @@
-'use strict';
+const lint = require('neutrino-lint-base');
+const merge = require('deepmerge');
 
-const path = require('path');
+module.exports = neutrino => {
-
+  lint(neutrino);
-const MODULES = path.join(__dirname, '../node_modules');
+  neutrino.config.module
-
-module.exports = ({ config }) => {
-  config
-    .module
     .rule('lint')
-        .test(/\.(js|jsx)$/)
+    .loader('eslint', props => merge(props, {
-        .pre()
+      options: {
-        .include(path.join(process.cwd(), 'src'))
-        .loader('eslint', require.resolve('eslint-loader'), {
-          failOnError: process.env.NODE_ENV !== 'development',
-          emitWarning: process.env.NODE_ENV !== 'development',
-          emitError: process.env.NODE_ENV !== 'development',
-          cwd: process.cwd(),
-          useEslintrc: false,
-          root: true,
-          plugins: ['babel'],
         baseConfig: {
           extends: ['airbnb-base']
         },
-          envs: ['es6'],
-          parser: 'babel-eslint',
-          parserOptions: {
-            ecmaVersion: 2017,
-            sourceType: 'module',
-            ecmaFeatures: {
-              objectLiteralDuplicateProperties: false,
-              generators: true,
-              impliedStrict: true
-            }
-          },
-          settings: {},
-          globals: ['process'],
         rules: {
           // handled by babel rules
           'new-cap': 'off',
@@ -51,8 +26,6 @@ module.exports = ({ config }) => {
           // guard against awaiting async functions inside of a loop
           'babel/no-await-in-loop': 'error'
         }
-        });
+      }
-
+    }));
-  config.resolve.modules.add(MODULES);
-  config.resolveLoader.modules.add(MODULES);
 };

packages/neutrino-preset-react/package.json

@@ -18,7 +18,7 @@
     "babel-preset-react": "^6.22.0",
     "deepmerge": "^1.3.2",
     "eslint-plugin-react": "^6.9.0",
-    "neutrino-preset-web": "4.0.0",
+    "neutrino-preset-web": "4.0.1",
     "react-hot-loader": "^3.0.0-beta.6",
     "webpack": "^2.2.1"
   },