Jest / Enzyme - 如何在不同的视口进行测试?

时间:2017-09-14 14:02:56

标签: jestjs viewport enzyme

我正在尝试对某个视口宽度的组件进行测试。我正在做以下事情,但这似乎没有改变它:

test('Component should do something at a certain viewport width.', () => {
    global.innerWidth = 2000;
    const component = mount(<SomeComponent />);
    ...
});

我还发现了一篇文章,解释了如何使用JSDom来实现它,但是当Jest现在随JSDom提供时,我想知道是否有原生解决方案。

https://www.codementor.io/pkodmad/dom-testing-react-application-jest-k4ll4f8sd

3 个答案:

答案 0 :(得分:6)

背景信息:

这里是一个例子:


comp.js

import * as React from 'react';

export default class Comp extends React.Component {
  constructor(...args) {
    super(...args);
    this.state = { width: 0, height: 0 }
  }
  updateDimensions = () => {
    this.setState({ width: window.innerWidth, height: window.innerHeight });
  }
  componentDidMount() {
    this.updateDimensions();
    window.addEventListener("resize", this.updateDimensions);
  }
  componentWillUnmount() {
    window.removeEventListener("resize", this.updateDimensions);
  }
  render() {
    return <div>{this.state.width} x {this.state.height}</div>;
  }
}

comp.test.js

import * as React from 'react';
import { shallow } from 'enzyme';

import Comp from './comp';

const resizeWindow = (x, y) => {
  window.innerWidth = x;
  window.innerHeight = y;
  window.dispatchEvent(new Event('resize'));
}

describe('Comp', () => {
  it('should display the window size', () => {
    const component = shallow(<Comp />);

    expect(component.html()).toEqual('<div>1024 x 768</div>');

    resizeWindow(500, 300);
    expect(component.html()).toEqual('<div>500 x 300</div>');

    resizeWindow(2880, 1800);
    expect(component.html()).toEqual('<div>2880 x 1800</div>');
  });
});

注意:

答案 1 :(得分:1)

如果您使用的是TypeScript,它将抱怨window.innerWidth / innerHeight是只读的。 您可以通过重新声明属性来解决此问题:

Object.defineProperty(window, 'innerWidth', {writable: true, configurable: true, value: 105})

或使用Object.assign方法:

window = Object.assign(window, { innerWidth: 105 });

这两种解决方案都不是很好,但是它们可以工作。

答案 2 :(得分:0)

为我工作。代码不再标记为已发现。

it('resize event listener changes the state', () => {
  const wrapper = shallow(<Component />);
  const instance = wrapper.instance();

  instance.setState({
    mobileMode: true
  });

  global.innerWidth = 800;
  window.dispatchEvent(new Event('resize'));
  expect(instance.state.mobileMode).toBeFalsy();

  global.innerWidth = 600;
  window.dispatchEvent(new Event('resize'));
  expect(instance.state.mobileMode).toBeTruthy();
});

在组件内部调整监听器的大小

...
 resizeListener = () => {
      if (window.innerWidth < 768) {
        this.setState({
          mobileMode: true
        });
      } else {
        this.setState({
          mobileMode: false
        });
      }
    };
    window.addEventListener('resize', resizeListener);
...