Vue-test-utils: $listeners is readonly error

[eddyerburgh]

Version

1.0.0-beta.14

Reproduction link

https://codesandbox.io/s/0y2o4p8zvv

Steps to reproduce

Visit reproduction link.

What is expected?

Should not warn

What is actually happening?

Warn that $listerns and $attrs is readonly

[tbsvttr]

@eddyerburgh Same problem here. Happened directly after upgrading from vue-test-utils Beta 12 to Beta 13! However, the problem stayed after upgrading from Beta 13 to Beta 14.

[timoschwarzer]

Might be related to #534

[eddyerburgh]

This is caused by the changes in beta.12 where we set all watchers to sync.

We set all watchers to sync, including the update watcher. This causes a re-render when the comonent updates the attrs. Then before the listeners have been updated, isUpdatingChildComponent is set to false, so when the listeners are mutated, the warning is logged.

[bdeo]

Is there a workaround for this/plan to resolve? I've confirmed this with Element-UI as well. I don't think this is Vuetify specific. Maybe title should remove Vuetify specifically. https://codesandbox.io/s/q377x6prx9

[eddyerburgh]

The plan to resolve is to add an async option to Vue that we will set to false. I have a PR open but it won't be added until Vue 2.6 in a months time.

The only solution I can think of for this issue is to set Vue to silent when running update watchers:

Vue.config.silent = true

You can see more info on the synchrnous issue —https://github.com/vuejs/vue-test-utils/issues/676

[ticdenis]

How can I silence these warnings?

[wordythebyrd]

@ticdenis, I believe @eddyerburgh is recommending you set Vue to silent. See the documentation.

Vue.config.silent = true

Suppress all Vue logs and warnings.

[ticdenis]

Thanks! My mistake in silencing was to try it with the localVue instance.

[bigtunacan]

I'm getting the following logged when running a test which appears related to this issue.

console.error node_modules/vue/dist/vue.runtime.common.js:589                                                                               [3/1000]
    [Vue warn]: $listeners is readonly.                                    

    found in                                                                                                                                          

    ---> <VAutocomplete>                                                   
           <Users>                                                                                                                                    
             <Root>                  

  console.error node_modules/vue/dist/vue.runtime.common.js:589                                                                                       
    [Vue warn]: Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders. Instead, use a data or co
mputed property based on the prop's value. Prop being mutated: "items"

    found in

    ---> <VAutocomplete>
           <Users>
             <Root>

  console.error node_modules/vue/dist/vue.runtime.common.js:589
    [Vue warn]: Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders. Instead, use a data or co
mputed property based on the prop's value. Prop being mutated: "selectedItems"

    found in

    ---> <VSelectList>
           <VMenu>
             <VAutocomplete>
               <Users>
                 <Root>

I set Vue.config.silent = true in my test\unit\index.js file as suggested above by @eddyerburgh but this is not surpressing errors.

I have also tried using $nextTick and async/await with flushPromises() to see if either of those methods would work here but no such luck.

Here is what this particular test looks like.

import { shallowMount, createLocalVue } from '@vue/test-utils';
import Vuex from 'vuex';
import Vuetify from 'vuetify';
import Users from '@/components/Users';

addElemWithDataAppToBody();

describe('Users.vue', () => {
  test('should render correct contents', () => {
    const localVue = createLocalVue();
    localVue.use(Vuetify);
    localVue.use(Vuex);

    // For Vuex
    let storeOptions;
    let store;

    storeOptions = {
      actions: {
      },
      getters: {
        shouldRefreshUser: jest.fn(),
      }
    };

    store = new Vuex.Store(storeOptions);

    let wrapper = shallowMount(Users, {store, localVue});

    let response = {
      results: [
        { name_uiowadisplay: 'Banana' },
        { name_uiowadisplay: 'Apple' },
        { name_uiowadisplay: 'Dragon Fruit' },
        { name_uiowadisplay: 'Cantaloupe' },
      ]
    };

    wrapper.vm.setSearchResults(response);

    expect(response.results[0].name_uiowadisplay).toBe('Apple');
    expect(response.results[1].name_uiowadisplay).toBe('Banana');
    expect(response.results[2].name_uiowadisplay).toBe('Cantaloupe');
    expect(response.results[3].name_uiowadisplay).toBe('Dragon Fruit');

  });
});

/**
 * Adds a warapping `div data-app="true"` to the body so that we don't
 * get Vuetify complaining about missing data-app attribute for some components.
 *
 * @return undefined
 */
function addElemWithDataAppToBody() {
  const app = document.createElement('div');
  app.setAttribute('data-app', true);
  document.body.append(app);
};

[tlbignerd]

I had the same issue @bigtunacan. Modifying mount to use sync: false with the beta.16 version fixed the issue for me.

let wrapper = shallowMount(Users, { store, localVue, sync: false })

My entire file looks like this (stubbing a child component, and we use apollo link state instead of Vuex).

import { mount, createLocalVue } from '@vue/test-utils'
import Vuetify from 'vuetify'
import VeeValidate from 'vee-validate'
import Component from '../search-panel'

const localVue = createLocalVue()
Vuetify.install(localVue)
localVue.use(VeeValidate)

describe('@components/search-panel', () => {
  let errors
  let $validator
  let $apollo

  beforeEach(() => {
    // Stub out errors to handle VeeValidate error display.
    errors = {
      any: jest.fn(),
      first: jest.fn(),
      split: jest.fn()
    }
    // Stub out Apollo so that calls are not made to the store or server.
    $apollo = {
      mutate: jest.fn(),
      query: jest.fn()
    }
    // Stub out VeeValidate validator
    $validator = new VeeValidate.Validator()

    // Handle errors with Vuetify not being able to locate the data-app target by stubbing an attribute.
    const el = document.createElement('div')
    el.setAttribute('data-app', true)
    document.body.appendChild(el)
  })

  it('has edit fields', () => {
    const wrapper = mount(Component, {
      localVue,
      sync: false,
      stubs: {
        MapInput: "<div name='MapInput' ref='map'></div>"
      },
      mocks: {
        errors,
        $apollo,
        $validator
      }
    })
    const fields = wrapper.findAll('.search-field')
    const fieldLabels = fields.wrappers.map(w => w.find('label').text())
    expect(fieldLabels.some(fl => fl === 'Mission ID')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Owner')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Agency')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Objects Detected')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Start Date')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Start Time')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'End Date')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'End Time')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Description')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Show Deleted')).toBeTruthy()
    expect(fieldLabels.some(fl => fl === 'Enterprise')).toBeTruthy()
  })

})

[nelsonsar]

I was facing this problem while dealing with a component that was using :visible.sync and made use of transitions and solved by using:

{
  stubs: {
    transition: false
  }
}

I'm not sure if all cases are related to these specific settings but, maybe it can be helpful for people facing similar problems.

[abdullah]

Is there any progress on it?

[johnleider]

I believe the fix here is waiting on 2.5.18 for Vue. We have also refactored the entire bootstrap process but it is a breaking change that won't come until 2.0

[Djaler]

2.5.18 was released

[builder7777]

The issue is still there

[eddyerburgh]

The fix relies on #1062