use yargs for option parsing and support config files

- `-d` is no longer an alias for `--debug`
- `--grep` and `--fgrep` are now mutually exclusive
- The option formerly known as `--compilers` is now removed from Mocha
- `lib/template.html` moved to `lib/browser/template.html`
- An error is thrown if a path to `mocha.opts` is specified by the user and the file was not found

- `-gc` users should use `--gc-global`

- Public API method `getOptions()` in `bin/options.js` is deprecated and currently has no alternative
- Users of the `enableTimeouts` option of the `Mocha` constructor should use `timeout` instead.  Specify `false` for no timeout
- Users of the `useColors` option of the `Mocha` constructor should use `color` instead

- Mocha now supports JS, JSON, YAML, or `package.json`-based config.
- Any/all configuration, including `mocha.opts` can be used in addition to command-line arguments, and everything will be merged as applicable
- Node/V8 flag support:
  - Support of all available `node` flags on a *per-version* basis
  - Support of any V8 flag by prepending `--v8-` to the option
  - These are supported within `mocha.opts` or config files
- More flexible command-line parsing including negation of any boolean flag by prepending `--no-` to the name
- Better `--help`
- Descriptions of interfaces in `--help` text
- A useful `Mocha` constructor
- Debug-related flags (e.g., `--inspect`) now *imply* `--no-timeouts`

- Many bug fixes around CLI option handling, e.g., closes mochajs#3475
- Fixes mochajs#3363, mochajs#2576, mochajs#3570
- `--no-timeouts` works

- Added new, updated, or rewrote documentation for all non-self-explanatory options
- Updated usage text, TOC
- Added section on configuration
- Added example configuration files in `example/config/`

- Updated many dev deps, mostly within existing semver ranges
- Removed `commander`
- Added production deps:
  - ansi-colors - color terminal output
  - findup-sync - find package.json and other config files
  - js-yaml - parse YAML
  - log-symbols - visual symbols for success/fail etc.
  - node-environment-flags - per-version allowed Node.js env flags
  - object.assign - for IE11
  - strip-json-comments - allow comments in JSON config files
  - wide-align - terminal formatting
  - yargs - option parser
  - yargs-parser - for compatible, lightweight parsing of config files
  - yargs-unparser - for passing config to `bin/_mocha` from `bin/mocha`

.eslintrc.yml

@@ -23,12 +23,14 @@ overrides:
     - karma.conf.js
     - .wallaby.js
     - bin/*
+    - lib/cli/**/*.js
+    - test/node-unit/**/*.js
     parserOptions:
       ecmaVersion: 6
     env:
       browser: no
   - files:
-    - test/**/*.js
+    - test/**/*.{js,mjs}
     env:
       mocha: yes
     globals:
@@ -37,4 +39,9 @@ overrides:
     - doc/**/*.js
     env:
       node: no
+  - files:
+    - test/**/*.mjs
+    parserOptions:
+      ecmaVersion: 6
+      sourceType: module
 

.mocharc.yml

@@ -0,0 +1,7 @@
+require: test/setup
+ui: bdd
+global:
+  - okGlobalA,okGlobalB
+  - okGlobalC
+  - callback*
+timeout: 200

.travis.yml

@@ -67,8 +67,8 @@ jobs:
       env: null
       before_install: true
       install: npm install --production
-      # `--opts /dev/null` means "ignore test/mocha.opts"
-      script: ./bin/mocha --opts /dev/null --reporter spec test/sanity/sanity.spec.js
+
+      script: ./bin/mocha --no-config --reporter spec test/sanity/sanity.spec.js
       cache:
         directories:
           - ~/.npm

.wallaby.js

@@ -3,26 +3,35 @@
 module.exports = () => {
   return {
     files: [
-      'index.js', 'lib/**/*.js', 'test/setup.js', 'test/assertions.js',
+      'index.js',
+      'lib/**/*.{js,json}',
+      'test/setup.js',
+      'test/assertions.js',
       {
         pattern: 'test/node-unit/**/*.fixture.js',
         instrument: false
-      }, {
+      },
+      {
         pattern: 'test/unit/**/*.fixture.js',
         instrument: false
-      }
+      },
+      'package.json',
+      'test/opts/mocha.opts',
+      'mocharc.yml'
     ],
-    filesWithNoCoverageCalculated: ['test/**/*.fixture.js'],
-    tests: [
-      'test/unit/**/*.spec.js', 'test/node-unit/**/*.spec.js'
+    filesWithNoCoverageCalculated: [
+      'test/**/*.fixture.js',
+      'test/setup.js',
+      'test/assertions.js'
     ],
+    tests: ['test/unit/**/*.spec.js', 'test/node-unit/**/*.spec.js'],
     env: {
       type: 'node',
       runner: 'node'
     },
     workers: {recycle: true},
     testFramework: {type: 'mocha', path: __dirname},
-    setup (wallaby) {
+    setup(wallaby) {
       // running mocha instance is not the same as mocha under test,
       // running mocha is the project's source code mocha, mocha under test is instrumented version of the source code
       const runningMocha = wallaby.testFramework;
@@ -33,7 +42,7 @@ module.exports = () => {
       // to make test/node-unit/color.spec.js pass, we need to run mocha in the project's folder context
       const childProcess = require('child_process');
       const execFile = childProcess.execFile;
-      childProcess.execFile = function () {
+      childProcess.execFile = function() {
         let opts = arguments[2];
         if (typeof opts === 'function') {
           opts = {};