From bcb70fdeacfc206615cde3ee915a1c6019922fc7 Mon Sep 17 00:00:00 2001
From: Jaon <jaon-z@live.com>
Date: Mon, 21 Sep 2020 03:52:07 -0300
Subject: [PATCH] add test filterModuleRules for next-plugin-storybook

---
 packages/next-plugin-storybook/preset.js      | 33 +++++++++++--------
 .../webpack-config-overrides.unit.test.js     | 13 ++++++++
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/packages/next-plugin-storybook/preset.js b/packages/next-plugin-storybook/preset.js
index 12ccb983e6063..806677aab0f5a 100644
--- a/packages/next-plugin-storybook/preset.js
+++ b/packages/next-plugin-storybook/preset.js
@@ -25,7 +25,25 @@ async function webpackFinal(config) {
     ...nextWebpackConfig.resolve,
   }
 
-  config.module.rules = [
+  config.module.rules = {
+    ...filterModuleRules(config),
+    ...nextWebpackConfig.module.rules.map((rule) => {
+      // we need to resolve next-babel-loader since it's not available
+      // relative with storybook's config
+      if (rule.use && rule.use.loader === 'next-babel-loader') {
+        rule.use.loader = require.resolve(
+          'next/dist/build/webpack/loaders/next-babel-loader'
+        )
+      }
+      return rule
+    }),
+  }
+
+  return config
+}
+
+function filterModuleRules(config) {
+  return [
     ...config.module.rules.filter((rule) => {
       // the rules we're filtering use RegExp for the test
       if (!(rule.test instanceof RegExp)) return true
@@ -43,21 +61,10 @@ async function webpackFinal(config) {
       }
       return true
     }),
-    ...nextWebpackConfig.module.rules.map((rule) => {
-      // we need to resolve next-babel-loader since it's not available
-      // relative with storybook's config
-      if (rule.use && rule.use.loader === 'next-babel-loader') {
-        rule.use.loader = require.resolve(
-          'next/dist/build/webpack/loaders/next-babel-loader'
-        )
-      }
-      return rule
-    }),
   ]
-
-  return config
 }
 
 module.exports = {
   webpackFinal,
+  filterModuleRules,
 }
diff --git a/test/unit/webpack-config-overrides.unit.test.js b/test/unit/webpack-config-overrides.unit.test.js
index 2a0af487e679a..c6c0a877b37a9 100644
--- a/test/unit/webpack-config-overrides.unit.test.js
+++ b/test/unit/webpack-config-overrides.unit.test.js
@@ -1,5 +1,18 @@
 /* eslint-env jest */
 import { attachReactRefresh } from 'next/dist/build/webpack-config'
+import * as storybookPlugin from '../../packages/next-plugin-storybook/preset'
+
+describe('next-plugin-storybook filterModuleRules', () => {
+  it('should filter module rules correctly', async () => {
+    const input = {
+      module: { rules: [{ test: 'babel-loader' }, { test: /.*\.css/ }] },
+    }
+    const expected = [{ test: 'babel-loader' }]
+
+    const output = storybookPlugin.filterModuleRules(input)
+    expect(output).toEqual(expected)
+  })
+})
 
 describe('webpack-config attachReactRefresh', () => {
   it('should skip adding when unrelated', () => {