test(load): adds test for importing plugins from an extended config

@commitlint/load/fixtures/extends-with-plugins/commitlint.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	extends: ['./config-with-plugins'],
+};

@commitlint/load/fixtures/extends-with-plugins/config-with-plugins/commitlint.config.js

@@ -0,0 +1,4 @@
+module.exports = {
+	extends: [],
+	plugins: ['example', '@scope/example']
+};

@commitlint/load/fixtures/extends-with-plugins/config-with-plugins/index.js

@@ -0,0 +1 @@
+module.exports = require('./commitlint.config.js');

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

@@ -95,6 +95,16 @@ test('plugins should be loaded from config', async () => {
 	});
 });
 
+test('plugins should be loaded from shareable config', async () => {
+	const cwd = await gitBootstrap('fixtures/extends-with-plugins');
+	const actual = await load({}, {cwd});
+
+	expect(actual.plugins).toMatchObject({
+		example: plugin,
+		'@scope/example': scopedPlugin
+	});
+});
+
 test('uses seed with parserPreset', async () => {
 	const cwd = await gitBootstrap('fixtures/parser-preset');
 	const {parserPreset: actual} = await load(