enzyme

What is enzyme?

Enzyme is a JavaScript testing utility for React that makes it easier to assert, manipulate, and traverse your React Components' output. It is designed to work with test runners like Jest or Mocha, and it provides a more intuitive and flexible API for interacting with React component trees.

What are enzyme's main functionalities?

Shallow Rendering

Shallow rendering is useful to constrain yourself to testing a component as a unit, and to ensure that your tests aren't indirectly asserting on behavior of child components.

import { shallow } from 'enzyme';
import MyComponent from './MyComponent';

const wrapper = shallow(<MyComponent />);
expect(wrapper.find('.my-class').length).toBe(1);

Full DOM Rendering

Full DOM rendering is ideal for use cases where you have components that may interact with DOM APIs, or may require the full lifecycle in order to fully test the component (i.e., componentDidMount etc.).

import { mount } from 'enzyme';
import MyComponent from './MyComponent';

const wrapper = mount(<MyComponent />);
expect(wrapper.find('.my-class').length).toBe(1);

Static Rendering

Static rendering is used to render the component to static HTML. It's useful for rendering components to strings, for instance, to send in emails, or for analyzing the markup structure.

import { render } from 'enzyme';
import MyComponent from './MyComponent';

const wrapper = render(<MyComponent />);
expect(wrapper.find('.my-class').length).toBe(1);

Other packages similar to enzyme

react-testing-library

React Testing Library is a very popular alternative to Enzyme that provides light utility functions on top of react-dom and react-dom/test-utils, in a way that encourages better testing practices. It focuses on testing components 'as the user would' rather than testing implementation details.

jest

Jest is a delightful JavaScript Testing Framework with a focus on simplicity. It works well with React and can be used as a test runner, assertion library, and mocking library. Jest's snapshot testing feature can be seen as an alternative to Enzyme's rendering capabilities.

README

Enzyme

Enzyme is a JavaScript Testing utility for React that makes it easier to assert, manipulate, and traverse your React Components' output.

Enzyme's API is meant to be intuitive and flexible by mimicking jQuery's API for DOM manipulation and traversal.

Enzyme is unopinionated regarding which test runner or assertion library you use, and should be compatible with all major test runners and assertion libraries out there. The documentation and examples for enzyme use mocha and chai, but you should be able to extrapolate to your framework of choice.

If you are interested in using enzyme with custom assertions and convenience functions for testing your React components, you can consider using:

• chai-enzyme with Mocha/Chai.
• jasmine-enzyme with Jasmine.
• jest-enzyme with Jest.
• should-enzyme for should.js.
• expect-enzyme for expect.

Using Enzyme with Mocha

Using Enzyme with Karma

Using Enzyme with Browserify

Using Enzyme with SystemJS

Using Enzyme with WebPack

Using Enzyme with JSDOM

Using Enzyme with React Native

Using Enzyme with Jest

Using Enzyme with Lab

Using Enzyme with Tape and AVA

Installation

To get started with enzyme, you can simply install it with npm:

npm i --save-dev enzyme

Enzyme is currently compatible with React 15.x, React 0.14.x and React 0.13.x. In order to achieve this compatibility, some dependencies cannot be explicitly listed in our package.json.

If you are using React 0.14 or React <15.5, in addition to enzyme, you will have to ensure that you also have the following npm modules installed if they were not already:

npm i --save-dev react-addons-test-utils react-dom

If you are using React >=15.5, in addition to enzyme, you will have to ensure that you also have the following npm modules installed if they were not already:

npm i --save-dev react-test-renderer react-dom

Basic Usage

Shallow Rendering

import React from 'react';
import { expect } from 'chai';
import { shallow } from 'enzyme';
import sinon from 'sinon';

import MyComponent from './MyComponent';
import Foo from './Foo';

describe('<MyComponent />', () => {
  it('renders three <Foo /> components', () => {
    const wrapper = shallow(<MyComponent />);
    expect(wrapper.find(Foo)).to.have.length(3);
  });

  it('renders an `.icon-star`', () => {
    const wrapper = shallow(<MyComponent />);
    expect(wrapper.find('.icon-star')).to.have.length(1);
  });

  it('renders children when passed in', () => {
    const wrapper = shallow((
      <MyComponent>
        <div className="unique" />
      </MyComponent>
    ));
    expect(wrapper.contains(<div className="unique" />)).to.equal(true);
  });

  it('simulates click events', () => {
    const onButtonClick = sinon.spy();
    const wrapper = shallow((
      <Foo onButtonClick={onButtonClick} />
    ));
    wrapper.find('button').simulate('click');
    expect(onButtonClick).to.have.property('callCount', 1);
  });
});

Read the full API Documentation

Full DOM Rendering

import React from 'react';
import sinon from 'sinon';
import { expect } from 'chai';
import { mount } from 'enzyme';

import Foo from './Foo';

describe('<Foo />', () => {
  it('allows us to set props', () => {
    const wrapper = mount(<Foo bar="baz" />);
    expect(wrapper.props().bar).to.equal('baz');
    wrapper.setProps({ bar: 'foo' });
    expect(wrapper.props().bar).to.equal('foo');
  });

  it('simulates click events', () => {
    const onButtonClick = sinon.spy();
    const wrapper = mount((
      <Foo onButtonClick={onButtonClick} />
    ));
    wrapper.find('button').simulate('click');
    expect(onButtonClick).to.have.property('callCount', 1);
  });

  it('calls componentDidMount', () => {
    sinon.spy(Foo.prototype, 'componentDidMount');
    const wrapper = mount(<Foo />);
    expect(Foo.prototype.componentDidMount).to.have.property('callCount', 1);
    Foo.prototype.componentDidMount.restore();
  });
});

Read the full API Documentation

Static Rendered Markup

import React from 'react';
import { expect } from 'chai';
import { render } from 'enzyme';

import Foo from './Foo';

describe('<Foo />', () => {
  it('renders three `.foo-bar`s', () => {
    const wrapper = render(<Foo />);
    expect(wrapper.find('.foo-bar').length).to.equal(3);
  });

  it('renders the title', () => {
    const wrapper = render(<Foo title="unique" />);
    expect(wrapper.text()).to.contain('unique');
  });
});

Read the full API Documentation

Future

Enzyme Future

Contributing

See the Contributors Guide

In the wild

Organizations and projects using enzyme can list themselves here.

License

MIT

Changelog

2.9.1

Fixes

• [Deps] Require uuid at least 3.0.1 (#1001)