Vue-Test-Utils Unknown custom element:

Question

I'm using Jest to run my tests utilizing the vue-test-utils library.

Even though I've added the VueRouter to the localVue instance, it says it can't actually find the router-link component. If the code looks a little funky, it's because I'm using TypeScript, but it should read pretty close to ES6... Main thing is that the @Prop() is the same as passing in props: {..}

Vue component:

<template>
  <div>
    <div class="temp">
      <div>
        <router-link :to="temp.url">{{temp.name}}</router-link>
      </div>
    </div>
  </div>
</template>

<script lang="ts">
import Vue from 'vue'
import Component from 'vue-class-component'
import { Prop } from 'vue-property-decorator'
import { Temp } from './Temp'

@Component({
  name: 'temp'
})
export default class TempComponent extends Vue {
  @Prop() private temp: Temp
}
</script>

<style lang="scss" scoped>
.temp {
  padding-top: 10px;
}
</style>

Temp model:

export class Temp {
  public static Default: Temp = new Temp(-1, '')

  public url: string

  constructor(public id: number, public name: string) {
    this.id = id
    this.name = name
    this.url = '/temp/' + id
  }
}

Jest test

import { createLocalVue, shallow } from '@vue/test-utils'
import TempComponent from '@/components/Temp.vue'
import { Temp } from '@/components/Temp'
import VueRouter from 'vue-router'

const localVue = createLocalVue()
localVue.use(VueRouter)

describe('Temp.vue Component', () => {
  test('renders a router-link tag with to temp.url', () => {
    const temp = Temp.Default
    temp.url = 'http://some-url.com'

    const wrapper = shallow(TempComponent, {
      propsData: { temp }
    })
    const aWrapper = wrapper.find('router-link')
    expect((aWrapper.attributes() as any).to).toBe(temp.url)
  })
})

What am I missing? The test actually passes, it just throws the warning. In fact, here is the output:

Test Output:

$ jest --config test/unit/jest.conf.js
 PASS  ClientApp\components\__tests__\temp.spec.ts
  Temp.vue Component
    √ renders a router-link tag with to temp.url (30ms)

  console.error node_modules\vue\dist\vue.runtime.common.js:589
    [Vue warn]: Unknown custom element: <router-link> - did you register the 
component correctly? For recursive components, make sure to provide the 
"name" option.

    (found in <Root>)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        4.677s
Ran all test suites.
Done in 6.94s.

Appreciate any help you can give!

Answer 1

Worked for me:

[ Package.json ] file

...
"vue-jest": "^3.0.5",
"vue-router": "~3.1.5",
"vue": "~2.6.11",
"@vue/test-utils": "1.0.0-beta.29",
...

[ Test ] file

import App from '../../src/App';
import { mount, createLocalVue } from '@vue/test-utils';
import VueRouter from 'vue-router';

const localVue = createLocalVue();
localVue.use(VueRouter);

const router = new VueRouter({
  routes: [
    {
      name: 'dashboard',
      path: '/dashboard'
    }
  ]
});

describe('Successful test', ()=>{
  it('works', ()=>{    
    let wrapper = mount(App, {
      localVue,
      router
    });

    // Here is your assertion
  });
});

Or you can try this:

Answer 2

Add the router-link stub to the shallow (or shallowMount) method options like this:

const wrapper = shallow(TempComponent, {
     propsData: { temp },
     stubs: ['router-link']
})

or this way:

import { RouterLinkStub } from '@vue/test-utils';

const wrapper = shallow(TempComponent, {
     propsData: { temp },
     stubs: {
         RouterLink: RouterLinkStub
     }
})

The error should go away after you do this.

Answer 3

const wrapper = shallow(TempComponent, {
  propsData: { temp },
  localVue
})