feat: add local plugins support

@commitlint/load/src/load.test.ts

@@ -63,6 +63,28 @@ test('plugins should be loaded from seed', async () => {
 	});
 });
 
+test('plugins should be loaded from local', async () => {
+	const actual = await load({
+		plugins: [
+			{
+				rules: {
+					test: () => [true, 'asd']
+				}
+			}
+		]
+	});
+
+	expect(actual.plugins).toEqual(
+		expect.objectContaining({
+			local: {
+				rules: {
+					test: expect.any(Function)
+				}
+			}
+		})
+	);
+});
+
 test('plugins should be loaded from config', async () => {
 	const cwd = await gitBootstrap('fixtures/extends-plugins');
 	const actual = await load({}, {cwd});

@commitlint/load/src/load.ts

@@ -86,8 +86,12 @@ export default async function load(
 
 	// resolve plugins
 	if (Array.isArray(config.plugins)) {
-		config.plugins.forEach((pluginKey: string) => {
-			loadPlugin(preset.plugins, pluginKey, process.env.DEBUG === 'true');
+		config.plugins.forEach(plugin => {
+			if (typeof plugin === 'string') {
+				loadPlugin(preset.plugins, plugin, process.env.DEBUG === 'true');
+			} else {
+				preset.plugins.local = plugin;
+			}
 		});
 	}
 

@commitlint/types/src/load.ts

@@ -96,7 +96,7 @@ export interface UserConfig {
 	parserPreset?: string | ParserPreset;
 	ignores?: ((commit: string) => boolean)[];
 	defaultIgnores?: boolean;
-	plugins?: string[];
+	plugins?: (string | Plugin)[];
 }
 
 export interface UserPreset {

docs/reference-plugins.md

@@ -43,6 +43,41 @@ Recommended keywords:
 
 Add these keywords into your `package.json` file to make it easy for others to find.
 
+## Local Plugins
+
+In case you want to develop your plugins locally without the need to publish to `npm`, you can send declare your plugins inside your project locally. Please be aware that you can declare **only one** local plugin.
+
+### Usage Example
+
+```js
+// commitlint.config.js
+module.exports = {
+  rules: {
+    'hello-world-rule': [2, 'always']
+  },
+  plugins: [
+    {
+      rules: {
+        'hello-world-rule': ({subject}) => {
+          const HELLO_WORLD = 'Hello World';
+          return [
+            subject.includes(HELLO_WORLD),
+            `Your subject should contain ${HELLO_WORLD} message`
+          ];
+        }
+      }
+    }
+  ]
+};
+```
+
+### Usage Example
+
+```bash
+> echo "feat: random subject" | commitlint # fails
+> echo "feat: Hello World" | commitlint # passes
+```
+
 ## Further Reading
 
 - [npm Developer Guide](https://docs.npmjs.com/misc/developers)