allow plugin in directory with index.js file (#3908)

* allow plugin in directory with index.js file

* add test for plugin in dir

* fix: refacto plugins key

lib/builder/builder.js

@@ -447,7 +447,7 @@ export default class Builder {
 
     // Check plugins exist then set alias to their real path
     await Promise.all(this.plugins.map(async (p) => {
-      const ext = path.extname(p.src) ? '' : '.+([^.])'
+      const ext = path.extname(p.src) ? '' : '{.+([^.]),/index.+([^.])}'
       const pluginFiles = await glob(`${p.src}${ext}`)
 
       if (!pluginFiles || pluginFiles.length === 0) {

test/fixtures/basic/nuxt.config.js

@@ -8,9 +8,6 @@ export default {
       maxAge: ((60 * 60 * 24 * 365) * 2)
     }
   },
-  plugins: [
-    '~/plugins/vuex-module'
-  ],
   router: {
     extendRoutes(routes, resolve) {
       return [{
@@ -64,6 +61,10 @@ export default {
     '': true
   },
   transition: false,
+  plugins: [
+    '~/plugins/vuex-module',
+    '~/plugins/dir-plugin'
+  ],
   build: {
     scopeHoisting: true,
     postcss: [

test/fixtures/basic/plugins/dir-plugin/index.js

@@ -0,0 +1,3 @@
+if (process.client) {
+  window.__test_plugin = true
+}

test/unit/basic.plugins.test.js

@@ -0,0 +1,25 @@
+import { getPort, loadFixture, Nuxt } from '../utils'
+
+let port
+const url = route => 'http://localhost:' + port + route
+
+let nuxt = null
+
+describe('with-config', () => {
+  beforeAll(async () => {
+    const config = await loadFixture('basic')
+    nuxt = new Nuxt(config)
+    port = await getPort()
+    await nuxt.listen(port, 'localhost')
+  })
+
+  test('/', async () => {
+    const window = await nuxt.renderAndGetWindow(url('/'))
+    expect(window.__test_plugin).toBe(true)
+  })
+
+  // Close server and ask nuxt to stop listening to file changes
+  afterAll(async () => {
+    await nuxt.close()
+  })
+})