问题

我一直在使用Jest和Enzyme为我的React组件编写测试，并使用了令人敬畏的Styled Components库 .

但是，由于我已经实现了主题，所以我的所有测试都在破坏 . 让我给你举个例子 .

这是我的 LooksBrowser 组件的代码（我删除了所有的import和prop-types以使其更具可读性）：

const LooksBrowserWrapper = styled.div`
  position: relative;
  padding: 0 0 56.25%;
`;

const CurrentSlideWrapper = styled.div`
  position: absolute;
  top: 0;
  left: 0;
  z-index: 2;
`;

const NextSlideWrapper = CurrentSlideWrapper.extend`
  z-index: 1;
`;

const SlideImage = styled.img`
  display: block;
  width: 100%;
`;

const SlideText = styled.div`
  display: flex;
  position: absolute;
  top: 25%;
  left: ${PXToVW(72)};
  height: 25%;
  flex-direction: column;
  justify-content: center;
`;

const SlideTitle = styled.p`
  flex: 0 0 auto;
  text-transform: uppercase;
  line-height: 1;
  color: ${props => props.color};
  font-family: ${props => props.theme.LooksBrowser.SlideTitle.FontFamily};
  font-size: ${PXToVW(52)};
`;

const SlideSubtitle = SlideTitle.extend`
  font-family: ${props => props.theme.LooksBrowser.SlideSubtitle.FontFamily};
`;

export default class LooksBrowser extends React.Component {
  state = {
    currentSlide: {
      imageURL: this.props.currentSlide.imageURL,
      index: this.props.currentSlide.index,
      subtitle: this.props.currentSlide.subtitle,
      textColor: this.props.currentSlide.textColor,
      title: this.props.currentSlide.title
    },
    nextSlide: {
      imageURL: this.props.nextSlide.imageURL,
      index: this.props.nextSlide.index,
      subtitle: this.props.nextSlide.subtitle,
      textColor: this.props.nextSlide.textColor,
      title: this.props.nextSlide.title
    },
    nextSlideIsLoaded: false
  };

  componentDidMount() {
    this.setVariables();
  }

  componentWillReceiveProps(nextProps) {
    // Only update the state when the nextSlide data is different than the current nextSlide data
    // and when the LooksBrowser component isn't animating
    if (this.props.nextSlide.imageURL !== nextProps.nextSlide.imageURL && !this.isAnimating) {
      this.setState(prevState => update(prevState, {
        nextSlide: {
          imageURL: { $set: nextProps.nextSlide.imageURL },
          index: { $set: nextProps.nextSlide.index },
          subtitle: { $set: nextProps.nextSlide.subtitle },
          textColor: { $set: nextProps.nextSlide.textColor },
          title: { $set: nextProps.nextSlide.title }
        }
      }));
    }
  }

  componentDidUpdate() {
    if (!this.isAnimating) {
      if (this.state.nextSlide.imageURL !== '' && this.state.nextSlideIsLoaded) {
        // Only do the animation when the nextSlide is done loading and it defined inside of the state
        this.animateToNextSlide();
      } else if (this.state.currentSlide.imageURL !== this.props.nextSlide.imageURL && this.state.nextSlide.imageURL !== this.props.nextSlide.imageURL) {
        // This usecase is for when the LooksBrowser already received another look while still being in an animation
        // After the animation is done it checks if the new nextSlide data is different than the current currentSlide data
        // And also checks if the current nextSlide state data is different than the new nextSlide data
        // If so, it updates the nextSlide part of the state so that in the next render animateToNextSlide will be called
        this.setState(prevState => update(prevState, {
          nextSlide: {
            imageURL: { $set: this.props.nextSlide.imageURL },
            index: { $set: this.props.nextSlide.index },
            subtitle: { $set: this.props.nextSlide.subtitle },
            textColor: { $set: this.props.nextSlide.textColor },
            title: { $set: this.props.nextSlide.title }
          }
        }));
      } else if (!this.state.nextSlideIsLoaded) {
        // Reset currentSlide position to prevent 'flash'
        TweenMax.set(this.currentSlide, {
          x: '0%'
        });
      }
    }
  }

  setVariables() {
    this.TL = new TimelineMax();
    this.isAnimating = false;
  }

  nextSlideIsLoaded = () => {
    this.setState(prevState => update(prevState, {
      nextSlideIsLoaded: { $set: true }
    }));
  };

  animateToNextSlide() {
    const AnimateForward = this.state.currentSlide.index < this.state.nextSlide.index;
    this.isAnimating = true;

    this.TL.clear();
    this.TL
      .set(this.currentSlide, {
        x: '0%'
      })
      .set(this.nextSlide, {
        x: AnimateForward ? '100%' : '-100%'
      })
      .to(this.currentSlide, 0.7, {
        x: AnimateForward ? '-100%' : '100%',
        ease: Quad.easeInOut
      })
      .to(this.nextSlide, 0.7, {
        x: '0%',
        ease: Quad.easeInOut,
        onComplete: () => {
          this.isAnimating = false;
          this.setState(prevState => update(prevState, {
            currentSlide: {
              imageURL: { $set: prevState.nextSlide.imageURL },
              index: { $set: prevState.nextSlide.index },
              subtitle: { $set: prevState.nextSlide.subtitle },
              textColor: { $set: prevState.nextSlide.textColor },
              title: { $set: prevState.nextSlide.title }
            },
            nextSlide: {
              imageURL: { $set: '' },
              index: { $set: 0 },
              subtitle: { $set: '' },
              textColor: { $set: '' },
              title: { $set: '' }
            },
            nextSlideIsLoaded: { $set: false }
          }));
        }
      }, '-=0.7');
  }

  render() {
    return(
      <LooksBrowserWrapper>
        <CurrentSlideWrapper innerRef={div => this.currentSlide = div} >
          <SlideImage src={this.state.currentSlide.imageURL} alt={this.state.currentSlide.title} />
          <SlideText>
            <SlideTitle color={this.state.currentSlide.textColor}>{this.state.currentSlide.title}</SlideTitle>
            <SlideSubtitle color={this.state.currentSlide.textColor}>{this.state.currentSlide.subtitle}</SlideSubtitle>
          </SlideText>
        </CurrentSlideWrapper>
        {this.state.nextSlide.imageURL &&
          <NextSlideWrapper innerRef={div => this.nextSlide = div}>
            <SlideImage src={this.state.nextSlide.imageURL} alt={this.state.nextSlide.title} onLoad={this.nextSlideIsLoaded} />
            <SlideText>
              <SlideTitle color={this.state.nextSlide.textColor}>{this.state.nextSlide.title}</SlideTitle>
              <SlideSubtitle color={this.state.nextSlide.textColor}>{this.state.nextSlide.subtitle}</SlideSubtitle>
            </SlideText>
          </NextSlideWrapper>
        }
      </LooksBrowserWrapper>
    );
  }
}

然后我现在测试我的 LooksBrowser 组件（以下是完整代码）：

import React from 'react';
import Enzyme, { mount } from 'enzyme';
import renderer from 'react-test-renderer';
import Adapter from 'enzyme-adapter-react-16';
import 'jest-styled-components';
import LooksBrowser from './../src/app/components/LooksBrowser/LooksBrowser';

Enzyme.configure({ adapter: new Adapter() });

test('Compare snapshots', () => {
  const Component = renderer.create(<LooksBrowser currentSlide={{ imageURL: 'http://localhost:3001/img/D1_VW_SPW.jpg', index: 1, subtitle: 'Where amazing happens', title: 'The United States of America', textColor: '#fff' }} nextSlide={{ imageURL: '', index: 0, subtitle: '', title: '', textColor: '' }} />);

  const Tree = Component.toJSON();
  expect(Tree).toMatchSnapshot();
});

test('Renders without crashing', () => {
  mount(<LooksBrowser currentSlide={{ imageURL: 'http://localhost:3001/img/D1_VW_SPW.jpg', index: 1, subtitle: 'Where amazing happens', title: 'The United States of America', textColor: '#fff' }} nextSlide={{ imageURL: '', index: 0, subtitle: '', title: '', textColor: '' }} />);
});

test('Check if componentDidUpdate gets called', () => {
  const spy = jest.spyOn(LooksBrowser.prototype, 'componentDidUpdate');
  const Component = mount(<LooksBrowser currentSlide={{ imageURL: 'http://localhost:3001/img/D1_VW_SPW.jpg', index: 1, subtitle: 'Where amazing happens', title: 'The United States of America', textColor: '#fff' }} nextSlide={{ imageURL: '', index: 0, subtitle: '', title: '', textColor: '' }} />);

  Component.setProps({ nextSlide: { imageURL: 'http://localhost:3001/img/D2_VW_SPW.jpg', index: 2, subtitle: 'Don\'t walk here at night', title: 'What A View', textColor: '#fff' } });
  expect(spy).toBeCalled();
});

test('Check if animateToNextSlide gets called', () => {
  const spy = jest.spyOn(LooksBrowser.prototype, 'animateToNextSlide');
  const Component = mount(<LooksBrowser currentSlide={{ imageURL: 'http://localhost:3001/img/D1_VW_SPW.jpg', index: 1, subtitle: 'Where amazing happens', title: 'The United States of America', textColor: '#fff' }} nextSlide={{ imageURL: '', index: 0, subtitle: '', title: '', textColor: '' }} />);

  Component.setProps({ nextSlide: { imageURL: 'http://localhost:3001/img/D2_VW_SPW.jpg', index: 2, subtitle: 'Don\'t walk here at night', title: 'What A View', textColor: '#fff' } });
  Component.setState({ nextSlideIsLoaded: true });
  expect(spy).toBeCalled();
});

在我实现它们之前，所有这些测试都在通过 . 实现主题后，每次测试都会出现以下错误：

TypeError: Cannot read property 'SlideTitle' of undefined

  44 |   line-height: 1;
  45 |   color: ${props => props.color};
> 46 |   font-family: ${props => props.theme.LooksBrowser.SlideTitle.FontFamily};
  47 |   font-size: ${PXToVW(52)};
  48 | `;
  49 |

好的，有道理 . 主题未定义 .

解决方案一

所以经过一些谷歌搜索后，我发现了以下“解决方案”：

https://github.com/styled-components/jest-styled-components#theming

推荐的解决方案是将主题作为prop传递：const wrapper = shallow（<Button theme = />）

所以我将以下代码添加到我的 LooksBrowser 测试文件中：

const theme = {
  LooksBrowser: {
    SlideTitle: {
      FontFamily: 'Futura-Light, sans-serif'
    },
    SlideSubtitle: {
      FontFamily: 'Futura-Demi, sans-serif'
    }
  }
};

并编辑我的所有测试以手动传递主题 . 例如：

test('Compare snapshots', () => {
  const Component = renderer.create(<LooksBrowser theme={theme} currentSlide={{ imageURL: 'http://localhost:3001/img/D1_VW_SPW.jpg', index: 1, subtitle: 'Where amazing happens', title: 'The United States of America', textColor: '#fff' }} nextSlide={{ imageURL: '', index: 0, subtitle: '', title: '', textColor: '' }} />);

  const Tree = Component.toJSON();
  expect(Tree).toMatchSnapshot();
});

完成后我再次运行测试 . 仍然出现相同的错误 .

解决方案二

我决定将我的组件包装在Styled Components ThemeProvider中 . 这修复了我的 Compare snapshots 和 Renders without crashing 测试中的错误 .

但是，因为我也在更改我的 LooksBrowser 组件的道具/状态并测试结果，所以这不再起作用了 . 这是因为 setProps 和 setState 函数只能在根/包装器组件上使用 .

因此，将我的组件包装在 ThemeProvider 组件中也不是有效的解决方案 .

解决方案三

我决定尝试记录我的一个Styled Components的道具 . 所以我将 SlideTitle 子组件更改为：

const SlideTitle = styled.p`
  flex: 0 0 auto;
  text-transform: uppercase;
  line-height: 1;
  color: ${props => {
    console.log(props.theme.LooksBrowser.SlideTitle.FontFamily);
    return props.color;
  }};
  font-family: ${props => props.theme.LooksBrowser.SlideTitle.FontFamily};
  font-size: ${PXToVW(52)};
`;

我收到以下错误：

TypeError: Cannot read property 'SlideTitle' of undefined

  44 |   line-height: 1;
  45 |   color: ${props => {
> 46 |     console.log(props.theme.LooksBrowser.SlideTitle.FontFamily);
  47 |     return props.color;
  48 |   }};
  49 |   font-family: ${props => props.theme.LooksBrowser.SlideTitle.FontFamily};

好吧，似乎整个主题道具都是空的 . 让我们尝试手动将主题传递给 SlideTitle （这是一个可怕的解决方案顺便说一句，这意味着我需要手动将我的主题传递给我整个项目中的每个样式组件） .

所以我添加了以下代码：

<SlideTitle theme={this.props.theme} color{this.state.currentSlide.textColor}>{this.state.currentSlide.title}</SlideTitle>

然后我再次进行测试 . 我在终端中看到以下行：

console.log src/app/components/LooksBrowser/LooksBrowser.js:46
Futura-Light, sans-serif

是的，这就是我要找的！我向下滚动，再次看到同样的错误......哎呀 .

解决方案四

在Jest Styled Components documentation我也看到了以下解决方案：

const shallowWithTheme = (tree, theme) => {
  const context = shallow(<ThemeProvider theme={theme} />)
    .instance()
    .getChildContext()
  return shallow(tree, { context })
}

const wrapper = shallowWithTheme(<Button />, theme)

好吧，看起来很有前途所以我将这个函数添加到我的测试文件中并将我的 Check if componentDidUpdate gets called 测试更新为：

test('Check if componentDidUpdate gets called', () => {
  const spy = jest.spyOn(LooksBrowser.prototype, 'componentDidUpdate');
  const Component = shallowWithTheme(<LooksBrowser currentSlide={{ imageURL: 'http://localhost:3001/img/D1_VW_SPW.jpg', index: 1, subtitle: 'Where amazing happens', title: 'The United States of America', textColor: '#fff' }} nextSlide={{ imageURL: '', index: 0, subtitle: '', title: '', textColor: '' }} />, Theme);

  Component.setProps({ nextSlide: { imageURL: 'http://localhost:3001/img/D2_VW_SPW.jpg', index: 2, subtitle: 'Don\'t walk here at night', title: 'What A View', textColor: '#fff' } });
  expect(spy).toBeCalled();
});

我运行测试并得到以下错误：

Error
Cannot tween a null target. thrown

因为我正在使用shallow，所以有道理 . 所以我改变函数使用mount而不是浅：

const shallowWithTheme = (tree, theme) => {
  const context = mount(<ThemeProvider theme={theme} />)
    .instance()
    .getChildContext()
  return mount(tree, { context })
}

我再次进行测试，瞧不起：

TypeError: Cannot read property 'SlideTitle' of undefined

我正式没有想法 .

如果有人对此有任何想法，将不胜感激！在此先感谢大家 .

编辑

我现在还在Github上打开了两个问题，一个在Styled Components repo，一个在Jest Styled Components repo .

到目前为止，我已经尝试了所有提供的解决方案，但没有任何效果 . 所以，如果有人在这里有 any ideas 如何解决这个问题请分享！

1 回答

我已经设法在同事的帮助下解决了这个问题 . 我有另一个组件扩展 SlideTitle 组件，打破了测试：

const SlideSubtitle = SlideTitle.extend`
  font-family: ${props => 
  props.theme.LooksBrowser.SlideSubtitle.FontFamily};
`;

我重构了我的代码：

const SlideTitlesSharedStyling = styled.p`
  flex: 0 0 auto;
  text-transform: uppercase;
  line-height: 1;
  color: ${props => props.color};
  font-size: ${PXToVW(52)};
`;

const SlideTitle = SlideTitlesSharedStyling.extend`
  font-family: ${props => props.theme.LooksBrowser.SlideTitle.FontFamily};
`;

const SlideSubtitle = SlideTitlesSharedStyling.extend`
  font-family: ${props => props.theme.LooksBrowser.SlideSubtitle.FontFamily};
`;

我的测试又开始了！

回复于 2024-05-06T06:19:36+08:00

无法让Jest使用包含主题的Styled Components

问题

解决方案一

解决方案二

解决方案三

解决方案四

编辑

1 回答

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