@vue/test-utils

What is @vue/test-utils?

@vue/test-utils is the official unit testing utility library for Vue.js. It provides methods to mount and interact with Vue components in an isolated manner, allowing developers to write unit tests for their Vue components effectively.

What are @vue/test-utils's main functionalities?

Mounting Components

Mounting components allows you to render a Vue component in a test environment and returns a wrapper that contains the mounted component and methods to interact with it.

import { mount } from '@vue/test-utils';
import MyComponent from './MyComponent.vue';

const wrapper = mount(MyComponent);

Finding Elements

Finding elements within the mounted component using CSS selectors, Vue component options, or ref attributes, which can then be used to test the component's behavior.

const button = wrapper.find('button');

Simulating User Interaction

Simulating user interactions such as clicks, typing, or other events on the mounted component to test how it responds to user input.

button.trigger('click');

Accessing Component Data and Methods

Accessing the Vue instance's data, computed properties, and methods to assert their values and behavior within the test.

const vm = wrapper.vm;
console.log(vm.someData);

Stubbing Child Components

Stubbing child components to prevent their actual implementation from being rendered, which can simplify tests and improve test performance.

const wrapper = mount(MyComponent, {
  stubs: {
    ChildComponent: true
  }
});

Other packages similar to @vue/test-utils

enzyme

Enzyme is a JavaScript testing utility for React that is similar to @vue/test-utils but for React components. It allows for shallow rendering, full DOM rendering, and static rendering. Enzyme provides a more granular approach to testing React components compared to @vue/test-utils.

react-testing-library

React Testing Library is another testing library for React that focuses on testing components in a way that resembles how users would interact with them, rather than testing implementation details. It is similar to @vue/test-utils in philosophy but tailored for React.

angular-testing-library

Angular Testing Library is a set of helpers for testing Angular components with a focus on the user experience. Like @vue/test-utils, it provides utilities for interacting with components, but it is designed specifically for the Angular framework.

README

Vue Test Utils

Component testing utils for Vue 3.

Installation and Usage

• yarn: yarn add @vue/test-utils --dev
• npm: npm install @vue/test-utils --save-dev

Get started with the documentation.

Coming from Vue 2 + Test Utils v1?

Check the migration guide. It's still a work in progress. If you find a problem or something that doesn't work that previously did in Vue Test Utils v1, please open an issue.

Documentation

See the docs.

Development

Get started by running yarn install. You can run the tests with yarn test. That's it!

Comparison with Vue Test Utils v1 (targeting Vue 2)

This is table for those coming from VTU 1, comparing the two APIs. Some things are still a work in progress.

• ✅ - implemented
• ❌ - not yet implemented
• ⚰️ - will not be implemented (if you have a compelling use case, please open an issue)

Mounting Options

option	status	notes
data	✅
slots	✅
mocks	✅	nested in global
propsData	✅	now called props
provide	✅	nested in global
mixins	✅	(new!) nested in global
plugins	✅	(new!) nested in global
component	✅	(new!) nested in global
directives	✅	(new!) nested in global
stubs	✅
attachToDocument	✅	renamed attachTo. See here
attrs	✅
scopedSlots	⚰️	scopedSlots are merged with slots in Vue 3
context	⚰️	different from Vue 2, does not make sense anymore.
localVue	⚰️	no longer required - Vue 3 there is no global Vue instance to mutate.
listeners	⚰️	no longer exists in Vue 3
parentComponent	⚰️

Wrapper API (mount)

method	status	notes
attributes	✅
classes	✅
exists	✅
find	✅	only querySelector syntax is supported. find(Comp) under discussion here
emitted	✅
findAll	✅	see above. .vm is different to Vue 2. We are exploring options.
get	✅
html	✅
setValue	✅	works for select, checkbox, radio button, input, textarea. Returns nextTick.
text	✅
trigger	✅	returns nextTick. You can do await wrapper.find('button').trigger('click')
setProps	✅
props	✅
setData	✅
destroy	✅	renamed to unmount to match Vue 3 lifecycle hook name.
props	✅
isVisible	✅
contains	⚰️	use find
emittedByOrder	⚰️	use emitted
setSelected	⚰️	now part of setValue
setChecked	⚰️	now part of setValue
is	⚰️
isEmpty	⚰️	use matchers such as this
isVueInstance	⚰️
name	⚰️
setMethods	⚰️