add custom reporter tutorial to API documentation

- configuration to support tutorials
- sort jsdoc config object because fussy

docs/_config.yml

@@ -1,9 +1,11 @@
+# Jekyll config
+
 url: https://mochajs.org
 exclude:
   - README.md
   - .*
   - LICENSE*
+  - api-tutorials
   - API.md
 repository: mochajs/mocha
 source: docs
-

docs/api-tutorials/custom-reporter.md

@@ -0,0 +1,113 @@
+Mocha allows you to define and use custom reporters install via `npm`.
+
+For example, if `mocha-foo-reporter` was published to the npm registry, you could install it via `npm install mocha-foo-reporter -D`, then use it via `mocha --reporter mocha-foo-reporter`.
+
+## Example Custom Reporter
+
+If you're looking to get started quickly, here's an example of a custom reporter.
+
+```js
+// my-reporter.js
+
+const Mocha = require('mocha');
+const {
+  RUNNER_EVENT_END,
+  RUNNER_EVENT_FAIL,
+  RUNNER_EVENT_PASS,
+  RUNNER_EVENT_SUITE,
+  RUNNER_EVENT_SUITE_END
+} = Mocha.Runner.constants;
+const Base = Mocha.reporters.Base;
+
+// this reporter outputs test results, indenting two spaces per suite
+class MyReporter extends Base {
+  constructor(runner) {
+    super(runner);
+
+    this._indents = 0;
+
+    runner
+      .once(RUNNER_EVENT_START, () => {
+        console.log('start');
+      })
+      .on(RUNNER_EVENT_SUITE, () => {
+        this.increaseIndent();
+      })
+      .on(RUNNER_EVENT_SUITE_END, () => {
+        this.decreaseIndent();
+      })
+      .on(RUNNER_EVENT_PASS, test => {
+        // Test#fullTitle() returns the suite name(s)
+        // prepended to the test title
+        console.log(`${this.indent()}pass: ${test.fullTitle()}`);
+      })
+      .on(RUNNER_EVENT_FAIL, (test, err) => {
+        console.log(
+          `${this.indent()}fail: ${test.fullTitle()} - error: ${err.message}`
+        );
+      })
+      .once(RUNNER_EVENT_END, () => {
+        // Base reporter has a `stats` property
+        console.log(
+          `end: ${this.stats.passes}/${this.stats.passes +
+            this.stats.failures} ok`
+        );
+      });
+  }
+
+  indent() {
+    return Array(this._indents)
+      .fill('  ')
+      .join('');
+  }
+
+  increaseIndent() {
+    this._indents++;
+  }
+
+  decreaseIndent() {
+    this._indents--;
+  }
+}
+
+module.exports = MyReporter;
+```
+
+To use this reporter, execute `mocha --reporter /path/to/my-reporter.js`.
+
+For further examples, the built-in reporter implementations are the [best place to look](<(https://github.com/mochajs/mocha/tree/master/lib/reporters)>). The [integration tests](https://github.com/mochajs/mocha/tree/master/test/reporters) may also be helpful.
+
+## Events
+
+A reporter should listen for events emitted from the `runner` (an instance of [Runner]).
+
+The event names are exported from the `constants` property of `Mocha.Runner`:
+
+| Constant                 | Event Name  | Event Arguments | Description                                                                                 |
+| ------------------------ | ----------- | --------------- | ------------------------------------------------------------------------------------------- |
+| `RUNNER_EVENT_END`       | `end`       | _(n/a)_         | All [Suite]s, [Test]s and [Hook]s have completed execution                                  |
+| `RUNNER_EVENT_FAIL`      | `fail`      | `Test`, `Error` | A [Test] has failed or thrown an exception                                                  |
+| `RUNNER_EVENT_HOOK`      | `hook`      | `Hook`          | A [Hook] is about to execute                                                                |
+| `RUNNER_EVENT_HOOK_END`  | `hook end`  | `Hook`          | A [Hook] has completed execution                                                            |
+| `RUNNER_EVENT_PASS`      | `pass`      | `Test`          | A [Test] has passed                                                                         |
+| `RUNNER_EVENT_PENDING`   | `pending`   | `Test`          | A [Test] was skipped                                                                        |
+| `RUNNER_EVENT_RETRY`     | `retry`     | `Test`, `Error` | A [Test] failed, but is about to be retried; never emitted unless `retry` option is nonzero |
+| `RUNNER_EVENT_START`     | `start`     | _(n/a)_         | Execution will begin                                                                        |
+| `RUNNER_EVENT_SUITE`     | `suite`     | `Suite`         | The [Hook]s and [Test]s within a [Suite] are about to be executed                           |
+| `RUNNER_EVENT_SUITE_END` | `suite end` | `Suite`         | The [Hook]s and [Test]s within a [Suite] (and any children [Suite]s) completed execution    |
+| `RUNNER_EVENT_TEST`      | `test`      | `Test`          | A [Test] is about to be executed                                                            |
+| `RUNNER_EVENT_TEST_END`  | `test end`  | `Test`          | A [Test] has completed execution                                                            |
+| `RUNNER_EVENT_WAITING`   | `waiting`   | _(n/a)_         | Waiting for `global.run()` to be called; only emitted when `delay` option is `true`         |
+
+**Please use these constants** instead of the event names in your own reporter! This will ensure compatibility with future versions of Mocha.
+
+> It's important to understand that all suite callbacks will be run _before_ the [Runner] emits `RUNNER_EVENT_START`. Hooks and tests, however, won't run until _after_ the [Runner] emits `RUNNER_EVENT_START`.
+
+## Custom Reporter for Browser
+
+As of Mocha v6.0.0, custom reporters are _only_ "officially" supported in Node.js. [Mochify](https://npm.im/mochify) might help you. YMMV!
+
+[runner]: /api/mocha.runner
+[test]: /api/mocha.test
+[hook]: /api/mocha.hook
+[suite]: /api/mocha.suite

docs/api-tutorials/jsdoc.tutorials.json

@@ -0,0 +1,5 @@
+{
+  "custom-reporter": {
+    "title": "Create a Custom Reporter"
+  }
+}

jsdoc.conf.json

@@ -1,32 +1,33 @@
 {
-  "tags": {
-    "allowUnknownTags": true
+  "markdown": {
+    "hardwrap": true,
+    "parser": "gfm"
   },
-  "source": {
-    "include": ["lib/", "./docs/API.md", "bin"]
+  "mocha-docdash": {
+    "sort": true,
+    "static": false
   },
-  "plugins": ["plugins/markdown"],
   "opts": {
-    "encoding": "utf8",
-    "template": "node_modules/@mocha/docdash",
     "destination": "docs/api",
+    "encoding": "utf8",
     "recurse": true,
+    "template": "node_modules/@mocha/docdash",
+    "tutorials": "./docs/api-tutorials",
     "verbose": true
   },
-  "markdown": {
-    "parser": "gfm",
-    "hardwrap": true
+  "plugins": ["plugins/markdown"],
+  "source": {
+    "include": ["lib/", "./docs/API.md", "bin"]
+  },
+  "tags": {
+    "allowUnknownTags": true
   },
   "templates": {
     "cleverLinks": false,
-    "monospaceLinks": false,
     "default": {
-      "outputSourceFiles": true,
-      "includeDate": false
-    }
-  },
-  "mocha-docdash": {
-    "static": false,
-    "sort": true
+      "includeDate": false,
+      "outputSourceFiles": true
+    },
+    "monospaceLinks": false
   }
 }