fix: improve createLocalVue and add more complete router tests

Author: yyx990803

src/create-local-vue.js

@@ -23,6 +23,11 @@ function createLocalVue (): Component {
   // so that merge strats registered by plguins can work properly
   instance.config.optionMergeStrategies = Vue.config.optionMergeStrategies
 
+  // make sure all extends are based on this instance.
+  // this is important so that global components registered by plugins,
+  // e.g. router-link are created using the correct base constructor
+  instance.options._base = instance
+
   // compat for vue-router < 2.7.1 where it does not allow multiple installs
   const use = instance.use
   instance.use = (plugin) => {

test/resources/components/component-with-router.vue

@@ -0,0 +1,6 @@
+<template>
+  <div>
+    <router-link to="/foo">foo</router-link>
+    <router-view></router-view>
+  </div>
+</template>

test/unit/specs/create-local-vue.spec.js

@@ -4,6 +4,7 @@ import VueRouter from 'vue-router'
 import mount from '~src/mount'
 import Component from '~resources/components/component.vue'
 import ComponentWithVuex from '~resources/components/component-with-vuex.vue'
+import ComponentWithRouter from '~resources/components/component-with-router.vue'
 
 describe('createLocalVue', () => {
   it('installs Vuex without polluting global Vue', () => {
@@ -63,17 +64,34 @@ describe('createLocalVue', () => {
     expect(typeof freshWrapper.vm.$route).to.equal('undefined')
   })
 
-  it('installs Router after a previous installed', () => {
+  it('Router should work properly with local Vue', () => {
     const localVue = createLocalVue()
     localVue.use(VueRouter)
     const routes = [
-      { path: '/foo', component: Component }
+      {
+        path: '/',
+        component: {
+          render: h => h('div', 'home')
+        }
+      },
+      {
+        path: '/foo',
+        component: {
+          render: h => h('div', 'foo')
+        }
+      }
     ]
     const router = new VueRouter({
       routes
     })
-    const wrapper = mount(Component, { localVue, router })
+    const wrapper = mount(ComponentWithRouter, { localVue, router })
     expect(wrapper.vm.$route).to.be.an('object')
+
+    expect(wrapper.text()).to.contain('home')
+
+    wrapper.find('a').trigger('click')
+    expect(wrapper.text()).to.contain('foo')
+
     const freshWrapper = mount(Component)
     expect(typeof freshWrapper.vm.$route).to.equal('undefined')
   })