feat: add store module HMR (#4582)

* feat: add store module HMR

* fix: replace export with window.$nuxt

Thanks to @pi0 for the suggestion :)

* refactor: apply only in dev mode on client side

* test: make store module test more descriptive

* fix: clear modules to apply HMR

* fix: remove console.log

* fix: e2e tests

* refactor: use void

packages/vue-app/template/store.js

@@ -3,12 +3,14 @@ import Vuex from 'vuex'
 
 Vue.use(Vuex)
 
-const files = require.context('@/<%= dir.store %>', true, /^\.\/(?!<%= ignorePrefix %>)[^.]+\.(<%= extensions %>)$/)
-const filenames = files.keys()
-
-// Store
 let storeData = {}
 
+let files;
+
+void function updateModules() {
+  files = require.context('@/<%= dir.store %>', true, /^\.\/(?!<%= ignorePrefix %>)[^.]+\.(<%= extensions %>)$/)
+  const filenames = files.keys()
+
   // Check if {dir.store}/index.js exists
   const indexFilename = filenames.find(filename => filename.includes('./index.'))
 
@@ -19,7 +21,7 @@ if (indexFilename) {
   // If store is not an exported method = modules store
   if (typeof storeData !== 'function') {
     // Store modules
-  if (!storeData.modules) {
+    if (!storeData.modules || module.hot) {
       storeData.modules = {}
     }
 
@@ -69,7 +71,19 @@ if (typeof storeData !== 'function') {
       module[name] = Object.assign({}, module[name], fileModule, appendedMods)
       module[name].namespaced = true
     }
+    // If the environment supports hot reloading...
+    <% if (isDev) { %>
+    if (process.client && module.hot) {
+      // Whenever any Vuex module is updated...
+      module.hot.accept(files.id, () => {
+        // Update `root.modules` with the latest definitions.
+        updateModules()
+        // Trigger a hot update in the store.
+        window.<%= globals.nuxt %>.$store.hotUpdate({ modules: storeData.modules })
+      })
+    }<% } %>
   }
+}()
 
 // createStore
 export const createStore = storeData instanceof Function ? storeData : () => {

test/e2e/basic.browser.test.js

@@ -78,8 +78,10 @@ describe('basic browser', () => {
   test('/store', async () => {
     await page.nuxt.navigate('/store')
 
-    expect(await page.$text('h1')).toBe('Vuex Nested Modules')
+    expect(await page.$text('h1')).toBe('foo/bar/baz: Vuex Nested Modules')
-    expect(await page.$text('p')).toBe('1')
+    expect(await page.$text('h2')).toBe('index/counter: 1')
+    expect(await page.$text('h3')).toBe('foo/blarg/getVal: 4')
+    expect(await page.$text('h4')).toBe('foo/bab/getBabVal: 10')
   })
 
   test('/head', async () => {

test/fixtures/basic/pages/store.vue

@@ -1,12 +1,14 @@
 <template>
   <div>
-    <h1>{{ baz }}</h1>
+    <h1>foo/bar/baz: {{ baz }}</h1>
     <br>
-    <p>{{ $store.state.counter }}</p>
+    <h2>index/counter: {{ $store.state.counter }}</h2>
     <br>
-    <h2>{{ getVal }}</h2>
+    <h3>foo/blarg/getVal: {{ getVal }}</h3>
     <br>
-    <h3>{{ getBabVal }}</h3>
+    <h4>foo/bab/getBabVal: {{ getBabVal }}</h4>
+    <br>
+    <button @click="$store.commit('increment')">+1</button>
   </div>
 </template>
 

test/unit/basic.ssr.test.js

@@ -70,8 +70,10 @@ describe('basic ssr', () => {
 
   test('/store', async () => {
     const { html } = await nuxt.server.renderRoute('/store')
-    expect(html).toContain('<h1>Vuex Nested Modules</h1>')
+    expect(html).toContain('<h1>foo/bar/baz: Vuex Nested Modules</h1>')
-    expect(html).toContain('<p>1</p>')
+    expect(html).toContain('<h2>index/counter: 1</h2>')
+    expect(html).toContain('<h3>foo/blarg/getVal: 4</h3>')
+    expect(html).toContain('<h4>foo/bab/getBabVal: 10</h4>')
   })
 
   test('/head', async () => {