Vue component register warning in unit tests with element-ui

Question

By element-ui documentation, it can be imported "entirely, or just import what you need". I have imported it entirely in application entry point main.js.

main.js

import Vue from 'vue'
import ElementUI from 'element-
import 'element-ui/lib/theme-chalk/index.css'

Vue.use(ElementUI)

const Component = () => import(/* webpackChunkName: "component" */ './views/Component.vue')

// eslint-disable-next-line no-new
new Vue({
  el: '#app',
  components: {Component}
})

Like that it is possible to use all element-ui components in my custom components. For example I've used button component in Component.vue. That looks fine and button is rendered in App.vue.

Component.vue

<template>
  <div>
    <el-button>{{ buttonText }}</el-button>
  </div>
</template>

<script>
  export default {
    name: 'component',

    data () {
      return {
        buttonText: 'Button Text'
      }
    },

    components: {}
  }
</script>

Now I have created test against this component using vue-jest and @vue/test-utils where I am testing is text in the button is rendered correctly. The test passed but I have Vue warning that button component is not registered:

[Vue warn]: Unknown custom element: - did you register the component correctly? For recursive components, make sure to provide the "name" option.

This is probably happening because I have imported all element-ui components directly in main.js file (as they propose in documentation) and not in Component.vue. Does anybody know how can I avoid this warning or how can I import component in the test?

Component.spec.js

import { shallow } from '@vue/test-utils'
import Component from '../Component.vue'

describe('Component.vue', () => {
  test('sanity test', () => {
    expect(true).toBe(true)
  })

  test('renders button title', () => {
    const wrapper = shallow(Component)
    wrapper.setData({buttonText: 'This is text'})
    expect(wrapper.text()).toEqual('This is text')
  })
})

Answer 1

In your tests, create a local Vue, call .use in it and pass it to shallow:

import { shallow , createLocalVue} from '@vue/test-utils';   // changed
import Vue from 'vue';                                       // added
import ElementUI from 'element-ui';                          // added
import Component from '../Component.vue'

const localVue = createLocalVue();                           // added
localVue.use(ElementUI);                                     // added

describe('Component.vue', () => {
  test('sanity test', () => {
    expect(true).toBe(true)
  })

  test('renders button title', () => {
    const wrapper = shallow(Component, {localVue})           // changed