From 49136bcd1b870958a12a269f2eb806c465251f02 Mon Sep 17 00:00:00 2001
From: Pim <pimlie@hotmail.com>
Date: Tue, 1 Oct 2019 13:04:24 +0200
Subject: [PATCH] fix(core): clear resolver cache for project files dev mode
 (#6490)

---
 packages/core/src/resolver.js       | 17 +++++++++++++++--
 packages/core/test/resolver.test.js |  2 +-
 packages/utils/src/cjs.js           |  8 ++++++--
 packages/utils/test/cjs.test.js     | 14 ++++++++++++++
 4 files changed, 36 insertions(+), 5 deletions(-)
 create mode 100644 packages/utils/test/cjs.test.js

diff --git a/packages/core/src/resolver.js b/packages/core/src/resolver.js
index 52803afe84..bcded60ef6 100644
--- a/packages/core/src/resolver.js
+++ b/packages/core/src/resolver.js
@@ -3,7 +3,12 @@ import fs from 'fs-extra'
 import consola from 'consola'
 import esm from 'esm'
 
-import { startsWithRootAlias, startsWithSrcAlias } from '@nuxt/utils'
+import {
+  startsWithRootAlias,
+  startsWithSrcAlias,
+  isExternalDependency,
+  clearRequireCache
+} from '@nuxt/utils'
 
 export default class Resolver {
   constructor (nuxt) {
@@ -138,9 +143,17 @@ export default class Resolver {
       lastError = e
     }
 
+    const isExternal = isExternalDependency(resolvedPath)
+
+    // in dev mode make sure to clear the require cache so after
+    // a dev server restart any changed file is reloaded
+    if (this.options.dev && !isExternal) {
+      clearRequireCache(resolvedPath)
+    }
+
     // By default use esm only for js,mjs files outside of node_modules
     if (useESM === undefined) {
-      useESM = /.(js|mjs)$/.test(resolvedPath) && !/node_modules/.test(resolvedPath)
+      useESM = !isExternal && /.(js|mjs)$/.test(resolvedPath)
     }
 
     // Try to require
diff --git a/packages/core/test/resolver.test.js b/packages/core/test/resolver.test.js
index 8c3ac46e53..4b0deb4482 100644
--- a/packages/core/test/resolver.test.js
+++ b/packages/core/test/resolver.test.js
@@ -442,7 +442,7 @@ describe('core: resolver', () => {
       const resolver = new Resolver({
         options: {}
       })
-      resolver.resolvePath = jest.fn()
+      resolver.resolvePath = jest.fn().mockReturnValue('/var/nuxt/resolver/file.js')
       resolver.esm = jest.fn()
 
       resolver.requireModule('/var/nuxt/resolver/file.js', { esm: true })
diff --git a/packages/utils/src/cjs.js b/packages/utils/src/cjs.js
index 453fca7da2..8b06c43507 100644
--- a/packages/utils/src/cjs.js
+++ b/packages/utils/src/cjs.js
@@ -1,6 +1,10 @@
+export function isExternalDependency (id) {
+  return /[/\\]node_modules[/\\]/.test(id)
+}
+
 export function clearRequireCache (id) {
   const entry = require.cache[id]
-  if (!entry || id.includes('node_modules')) {
+  if (!entry || isExternalDependency(id)) {
     return
   }
 
@@ -17,7 +21,7 @@ export function clearRequireCache (id) {
 
 export function scanRequireTree (id, files = new Set()) {
   const entry = require.cache[id]
-  if (!entry || id.includes('node_modules') || files.has(id)) {
+  if (!entry || isExternalDependency(id) || files.has(id)) {
     return files
   }
 
diff --git a/packages/utils/test/cjs.test.js b/packages/utils/test/cjs.test.js
new file mode 100644
index 0000000000..4b5c1b9772
--- /dev/null
+++ b/packages/utils/test/cjs.test.js
@@ -0,0 +1,14 @@
+import { isExternalDependency, getPKG } from '../src/cjs'
+
+describe('util: cjs', () => {
+  test('isExternalDependency works', () => {
+    expect(isExternalDependency('/var/nuxt/node_modules/dependency.js')).toBe(true)
+    expect(isExternalDependency('/var/nuxt/dependency.js')).toBe(false)
+    expect(isExternalDependency('C:\\nuxt\\node_modules\\dependency.js')).toBe(true)
+    expect(isExternalDependency('C:\\nuxt\\dependency.js')).toBe(false)
+  })
+
+  test('getPKG should not throw error on non existing package', () => {
+    expect(() => getPKG('this-doesnt-existsw')).not.toThrow()
+  })
+})