jest-enzyme

What is jest-enzyme?

The jest-enzyme package provides a set of custom matchers for using Enzyme with Jest, making it easier to write and read tests for React components.

What are jest-enzyme's main functionalities?

toBeChecked

This matcher checks if a checkbox input is checked.

expect(wrapper.find('input[type="checkbox"]').first()).toBeChecked();

toHaveClassName

This matcher checks if a component has a specific class name.

expect(wrapper.find('.my-class')).toHaveClassName('my-class');

toHaveStyle

This matcher checks if a component has a specific inline style.

expect(wrapper.find('div')).toHaveStyle('display', 'none');

toContainReact

This matcher checks if a component contains a specific React element.

expect(wrapper).toContainReact(<MyComponent />);

toHaveText

This matcher checks if a component contains specific text.

expect(wrapper.find('p')).toHaveText('Hello World');

Other packages similar to jest-enzyme

jest-dom

jest-dom provides a set of custom matchers to test the state of the DOM. It is similar to jest-enzyme but is more focused on testing DOM nodes rather than React components specifically.

enzyme

Enzyme itself is a testing utility for React that makes it easier to assert, manipulate, and traverse your React Components' output. jest-enzyme is built on top of Enzyme to provide Jest matchers.

react-testing-library

react-testing-library is a lightweight solution for testing React components. It encourages testing components in a way that is similar to how users interact with them. It can be used with Jest and provides a different approach compared to Enzyme.

README

jest-enzyme

Quick Links

• Setup
• Assertions
• Jest Enzyme Environment
• Create React App
• TypeScript

Setup

The best setup is to use our jest environment jest-environment-enzyme.

If you prefer not to use the environment, you can also do this:

// package.json
"jest": {
  "setupFilesAfterEnv": ['./node_modules/jest-enzyme/lib/index.js'],
}

Assertions

• Not all assertions work with every rendering strategy. If you are wondering what rendering mechanism to use when, refer to enzyme's documentation.

• toBeChecked()
• toBeDisabled()
• toBeEmptyRender()
• toExist()
• toContainMatchingElement()
• toContainMatchingElements()
• toContainExactlyOneMatchingElement()
• toContainReact()
• toHaveClassName()
• toHaveDisplayName()
• toHaveHTML()
• toHaveProp()
• toHaveRef()
• toHaveState()
• toHaveStyle()
• toHaveTagName()
• toHaveText()
• toIncludeText()
• toHaveValue()
• toMatchElement()
• toMatchSelector()

toBeChecked()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toBeChecked();

Assert that the given wrapper is checked:

import React from 'react'
import {mount, shallow} from 'enzyme'

function Fixture() {
  return (
    <div>
      <input id="checked" defaultChecked />
      <input id="not" defaultChecked={false} />
      <input id="tertiary" defaultChecked checked={false} />
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('#checked')).toBeChecked();
expect(wrapper.find('#not')).not.toBeChecked();

toBeDisabled()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toBeDisabled();

Assert that the given wrapper is disabled:

import React from 'react'
import {mount, shallow} from 'enzyme'

function Fixture() {
  return (
    <div>
      <input id="disabled" disabled />
      <input id="not"/>
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('#disabled')).toBeDisabled();
expect(wrapper.find('#not')).not.toBeDisabled();

toBeEmptyRender()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toBeEmptyRender();

Assert that the given wrapper has an empty render (null or false):

function EmptyRenderFixture() {
  return null;
}

function NonEmptyRenderFixture() {
  return (
    <div>
      <EmptyRenderFixture />
    </div>
  );
}

const wrapper = mount(<EmptyRenderFixture />); // mount/render/shallow when applicable

expect(wrapper.find('EmptyRenderFixture')).toBeEmptyRender();
expect(wrapper).not.toBeEmptyRender();

toExist()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toExist();

Assert that the given enzyme wrapper has rendered content.

function Fixture() {
  return (
    <div>
      <span className="foo" />
      <span className="bar baz" />
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('span')).toExist();
expect(wrapper.find('ul')).not.toExist();

toContainMatchingElement()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toContainMatchingElement('.foo');

Assert that the given wrapper contains at least one match for the given selector:

function User(props) {
  return (
    <span className={props.className}>
      User {props.index}
    </span>
  );
}

User.propTypes = {
  index: PropTypes.number.isRequired,
  className: PropTypes.string,
};

function Fixture() {
  return (
    <div>
      <ul>
        <li>
          <User index={1} className="userOne" />
        </li>
        <li>
          <User index={2} className="userTwo" />
        </li>
      </ul>
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper).toContainMatchingElement('.userOne');
expect(wrapper).not.toContainMatchingElement('.userThree');

toContainMatchingElements()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toContainMatchingElements(2, '.foo');

Assert that the given wrapper contains a given number of matches for the given selector:

function User(props) {
  return (
    <span className={props.className}>
      User {props.index}
    </span>
  );
}

User.propTypes = {
  index: PropTypes.number.isRequired,
  className: PropTypes.string,
};

function Fixture() {
  return (
    <div>
      <ul>
        <li>
          <User index={1} className="userOne" />
        </li>
        <li>
          <User index={2} className="userTwo" />
        </li>
      </ul>
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper).toContainMatchingElements(2, 'User');
expect(wrapper).not.toContainMatchingElements(2, '.userTwo');

toContainExactlyOneMatchingElement()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toContainExactlyOneMatchingElement('.foo');

Assert that the given wrapper contains exactly one match for the given selector:

function User(props) {
  return (
    <span className={props.className}>
      User {props.index}
    </span>
  );
}

User.propTypes = {
  index: PropTypes.number.isRequired,
  className: PropTypes.string,
};

function Fixture() {
  return (
    <div>
      <ul>
        <li>
          <User index={1} className="userOne" />
        </li>
        <li>
          <User index={2} className="userTwo" />
        </li>
      </ul>
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper).toContainExactlyOneMatchingElement('.userOne');
expect(wrapper).not.toContainExactlyOneMatchingElement('User');

toContainReact()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toContainReact(<div>foo</div>);

Assert that the given wrapper contains the provided react instance:

class User extends React.Component {
  render () {
    return (
      <span>User {this.props.index}</span>
    )
  }
}

User.propTypes = {
  index: PropTypes.number.isRequired
}

class Fixture extends React.Component {
  render () {
    return (
      <div>
        <ul>
          <li><User index={1} /></li>
          <li><User index={2} /></li>
        </ul>
      </div>
    )
  }
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper).toContainReact(<User index={1} />);
expect(wrapper).not.toContainReact(<User index={9000} />);

toHaveClassName()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveClassName('foo');

Assert that the given wrapper has the provided className:

function Fixture() {
  return (
    <div>
      <span className="foo" />
      <span className="bar baz" />
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('.foo')).toHaveClassName('foo');
expect(wrapper.find('.foo')).not.toHaveClassName('baz');

expect(wrapper.find('.bar')).toHaveClassName('bar baz');
expect(wrapper.find('.bar')).toHaveClassName('baz');

toHaveDisplayName()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveDisplayName('div');

Assert that the wrapper is of a certain tag type:

function Fixture() {
  return (
    <div>
      <span id="span" />
    </div>
  );
}

const wrapper = mount(<Fixture />);

expect(wrapper.find('#span')).toHaveDisplayName('span');
expect(wrapper.find('#span')).not.toHaveDisplayName('div');

toHaveHTML()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveHTML('<div>html</div>');

Assert that the given wrapper has the provided html:

Note Quotations are normalized.

function Fixture() {
  return (
    <div id="root">
      <span id="child">Test</span>
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('#child')).toHaveHTML(
  '<span id="child">Test</span>'
);

toHaveProp()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveProp('foo', 'value');
expect().toHaveProp('foo');
expect().toHaveProp({foo: 'value'});

Assert that the given wrapper has the provided propKey and associated value if specified:

function User() { ... }
User.propTypes = {
  foo: PropTypes.string,
  bar: PropTypes.array,
};

function Fixture() {
  return (
    <div id="root">
      <User foo={'baz'} bar={[1,2,3]} />
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find(User)).toHaveProp('foo');
expect(wrapper.find(User)).toHaveProp('foo', 'baz');

expect(wrapper.find(User)).toHaveProp('bar');
expect(wrapper.find(User)).toHaveProp('bar', [1,2,3]);

expect(wrapper.find(User)).toHaveProp({
  bar: [1, 2, 3],
  foo: 'baz',
});

toHaveRef()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveRef('foo');

Assert that the mounted wrapper has the provided ref:

class Fixture extends React.Component {
  render() {
    return (
      <div>
        <span ref="child" />
      </div>
    );
  }
}

const wrapper = mount(<Fixture />);

expect(wrapper).toHaveRef('child');
expect(wrapper).not.toHaveRef('foo');

toHaveState()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveState('foo');
expect().toHaveState('foo', 'bar');
expect().toHaveState({ foo: 'bar' });

Assert that the component has the provided stateKey and optional value if specified:

class Fixture extends React.Component {
  constructor() {
    super();
    this.state = {
      foo: false,
    };
  }

  render() {
    return (
      <div />
    );
  }
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper).toHaveState('foo');
expect(wrapper).toHaveState('foo', false);
expect(wrapper).toHaveState({ foo: false });

toHaveStyle()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveStyle('height');
expect().toHaveStyle('height', '100%');
expect().toHaveStyle({ height: '100%' });

Assert that the component has style of the provided key and value:

function Fixture() {
  const style1 = { height: '100%' };
  const style2 = { flex: 8 };

  return (
    <div>
      <span id="style1" style={style1} />
      <span id="style2" style={style2} />
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('#style1')).toHaveStyle('height', '100%');
expect(wrapper.find('#style2')).toHaveStyle('flex', 8);

toHaveTagName()

Deprecated: Matcher toHaveTagName is deprecated. Use the replacement, toHaveDisplayName() instead.

toHaveText()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveText('bar');

Assert that the wrapper's text matches the provided text exactly, using a strict comparison (===).

function Fixture() {
  return (
    <div>
      <p id="full">Text</p>
      <p id="empty"></p>
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('#full')).toHaveText('Text');
expect(wrapper.find('#full')).not.toHaveText('Wrong');

expect(wrapper.find('#full')).toHaveText();
expect(wrapper.find('#empty')).not.toHaveText();

toIncludeText()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toIncludeText('bar');

Assert that the wrapper includes the provided text:

function Fixture() {
  return (
    <div>
      <p id="full">Some important text</p>
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('#full')).toIncludeText('important');
expect(wrapper.find('#full')).not.toIncludeText('Wrong');

toHaveValue()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toHaveValue('bar');

Assert that the given wrapper has the provided value:

function Fixture() {
  return (
    <div>
      <input defaultValue="test" />
      <input defaultValue="foo" value="bar" onChange={jest.genMockFunction()} />
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('input').at(0)).toHaveValue('test');
expect(wrapper.find('input').at(1)).toHaveValue('bar');

toMatchElement()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toMatchElement(<Foo />);
expect().toMatchElement(<Foo />, { ignoreProps: false });
expect().toMatchElement(<Foo />, { ignoreProps: false, verbose: false });

Assert the wrapper matches the provided react instance. This is a matcher form of Enzyme's wrapper.matchesElement(), which returns a bool with no indication of what caused a failed match. This matcher includes the actual and expected debug trees as contextual information when it fails. Like matchesElement(), props are ignored. If you want to compare prop values as well, pass { ignoreProps: false } as options. Uses enzyme's debug() under the hood and compares debug strings, which makes for a human readable diff when expects fail.

Example:

function Fixture() {
  return (
    <div>
      <span id="foo" className="bar" />
    </div>
  );
}

const wrapper = shallow(<Fixture />); // mount/render/shallow when applicable

expect(wrapper).toMatchElement(<Fixture />);
expect(wrapper.find('span')).toMatchElement(<span />);
expect(wrapper.find('span')).toMatchElement(
  <span id="foo" className="bar" />,
  { ignoreProps: false }
);
expect(wrapper).not.toMatchElement(<div />);

toMatchSelector()

render	mount	shallow
no	yes	yes

Ways to use this API:

expect().toMatchSelector('.foo');

Assert that the wrapper matches the provided selector:

function Fixture() {
  return (
    <div>
      <span id="foo" className="bar" />
    </div>
  );
}

const wrapper = mount(<Fixture />); // mount/render/shallow when applicable

expect(wrapper.find('span')).toMatchSelector('span');
expect(wrapper.find('span')).toMatchSelector('#foo');
expect(wrapper.find('span')).toMatchSelector('.bar');

Jest Enzyme Environment

There is a special environment to simplify using enzyme with jest. Check it out here

Usage with Create React App

If you are using Create React App, instead of adding to your package.json as above, you will need to add a src/setupTests.js file to your app, to import jest-enzyme:

// src/setupTests.js
import 'jest-enzyme';

This is documented on Create React App at the bottom of the Testing Components section. There is also more information about Initializing Test Environment.

Usage with TypeScript

As with Create React App, when using jest-enzyme with TypeScript and ts-jest, you'll need to add a setupTests.ts file to your app that explicitly imports jest-enzyme, and point the setupFilesAfterEnv field in your package.json file towards it:

// src/setupTests.ts
import 'jest-enzyme';

"jest": {
 "setupFilesAfterEnv": ["./src/setupTests.ts"],
},

This ensures that the type definitions bundled with jest-enzyme (which add extra Jest matchers and globals like shallow and mount) are included in your TypeScript project.