Enzyme

JavaScript Testing utilities for React

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Leland Richardson

Leland Richardson

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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.



Installation

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

npm i --save-dev enzyme

Enzyme is currently compatible with both 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, 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
npm i --save-dev react-dom



Basic Usage

Shallow Rendering

import { shallow } from 'enzyme';

describe('<MyComponent />', () => {

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

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

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

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

});

Read the full API Documentation

JSDOM Full Rendering

import {
  describeWithDOM,
  mount,
  spyLifecycle,
} from 'enzyme';

describeWithDOM('<Foo />', () => {

  it('calls componentDidMount', () => {
    spyLifecycle(Foo);
    const wrapper = mount(<Foo />);
    expect(Foo.prototype.componentDidMount.calledOnce).to.be.true;
  });

  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.calledOnce).to.be.true;
  });

});

Read the full API Documentation

Static Rendered Markup

import { render } from 'enzyme';

describe('<Foo />', () => {

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

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

});

Read the full API Documentation

Leland Richardson

Leland Richardson

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