Jest + Enzyme：如何测试图像 src？

Question

我有一个 Logo 组件：

import React from "react";
import logo from "assets/images/logo.png";

const Logo = () => {
  return <img style={{ width: 50 }} src={logo} alt="logo" />;
};

export default Logo;

测试文件：

import React from "react";
import Logo from "components/shared/Logo";

describe("<Logo />", () => {
  it("renders an image", () => {
    const logo = shallow(<Logo />);

    expect(logo.find("img").prop("src")).toEqual("blahh");
  });
});

但是当我运行测试时，出现了一些奇怪的错误：

$ NODE_PATH=src jest
 FAIL  src/tests/Logo.test.js
  ● <Logo /> › renders an image

    TypeError: val.entries is not a function

      at printImmutableEntries (node_modules/expect/node_modules/pretty-format/build/plugins/immutable.js:44:5)
      at Object.<anonymous>.exports.serialize (node_modules/expect/node_modules/pretty-format/build/plugins/immutable.js:178:12)

我应该如何测试图像 src === "assets/images/logo.png"？

Answer 1

我假设您在徽标组件附近的 __test__ 目录中编写测试。

无论如何，将您的“assets/images/logo.png”相对于您的测试文件导入。

如果你的项目结构是这样的

Project
├── assets 
│   └── images
├       |
│       └── logo.png
├── src 
│   └── components
├       |── Logo.js 
│       └── __tests__
├           └── logo.test.js 
└ 

首先，就像我说的那样，通过键入将图像导入您的 logo.test.js：

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

import Logo from "./../Logo"; 
import logoImage from "./../../../assets/images/logo.png;

describe("<Logo />", () => {
    it("renders an image", () => {
        const logo = shallow(<Logo />);
        
        expect(logo.find("img").prop("src")).toEqual(logoImage);

     });
 });

Answer 2

由于某种原因，此信息未明确突出显示。 在'Integration with wepack' 部分显示了如何使用transform 自动模拟静态资产：

如果 moduleNameMapper 不能满足您的要求，您可以使用 Jest 的 transform 配置选项来指定如何转换资产。例如，返回文件基本名称的转换器（如 require('logo.jpg'); 返回 'logo'）可以写成：

package.json

{
  "jest": {
    "transform": {
      "\\.(js|jsx)$": "babel-jest",
      "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/fileTransformer.js"
    }
  }
}

fileTransformer.js

const path = require('path');

module.exports = {
  process(src, filename, config, options) {
    return 'module.exports = ' + JSON.stringify(path.basename(filename)) + ';';
  },
};

所以这将使您的wrapper.props().src 成为一个字符串（适用于任何类型的匹配器，如.toEqual）。这也意味着expect(wrapper).toMatchSnapshot() 也可以像尊重图像路径的魅力一样工作。

[upd] 不要错过在配置中为 JS/JSX 文件指定 "babel-jest" 转换

Answer 3

/* **Image component** */
import React from "react";
import PropsTypes from "prop-types";
/** Image Component - This is shared component, You can use this component for rendering images
 * @param (string) altName
 * @param (string) fileName
 * @Return element
 */
const Image = props => {
  const { fileName, altName } = props;
  return <img src={`/images/${fileName}`} alt={altName}></img>;
};
/* Apply validation on Text Component */
Image.propTypes = {
  fileName: PropsTypes.string.isRequired,
  altName: PropsTypes.string.isRequired
};
Image.defaultProps = {
  fileName: "dummy.png",
  altName: "dummy"
};
export default Image;

/* Image.test.js */
import React from "react";
import { shallow } from "enzyme";
import Image from "./Image";

describe("Testing of Image component", () => {
  it("render image component with default value", () => {
    const wrapper = shallow(<Image />);
    expect(wrapper).toBeTruthy();
    expect(wrapper.find("img").length).toEqual(1);
  });
  it("render image component with props ", () => {
    const props = {
      fileName: "facebook.png",
      altName: "facebook"
    };
    const wrapper = shallow(<Image {...props} />);
    expect(wrapper).toBeTruthy();
    expect(wrapper.find("img").length).toEqual(1);
  });
});

Answer 4

像这样..

import React from "react";
import Logo from "components/shared/Logo";

describe("<Logo />", () => {
  it("renders an image with src correctly", () => {
    const wrapper= shallow(<Logo src="yourlogo.png" />);
    expect(wrapper.html()).toEqual('<img src="yourlogo.png"/>'); // implement your ".toEqual(...)" to your Logo component result 
  });
});

或者，访问你的 src 属性：

const wrapper = mount(<Logo src="blah..."/>);
expect(wrapper.find({ prop: 'src' })).to.have.length(1); // or any other check you need 

http://airbnb.io/enzyme/docs/api/ReactWrapper/find.html

Answer 5

这对我有用...

组件：

function Header() {
        return (
            <div className="header">
                <img src="images/logo.png" alt="no logo found"/>
            </div>
        )
    }

测试：

it('should set logo image src correctly', () => {
        const logoImg = mountedHeader.find('img')
        expect(logoImg.getElement(0).props.src).toEqual("images/logo.png")
    });

https://acloud.guru/forums/serverless-portfolio-with-react/discussion/-KxEN_3qG3G9oxSHjyAN/Testing%20React%20-%20Testing%20images%20using%20expect(image.node.props.src)

Answer 6

describe("CharacterInfo", () => {
  const data={
    image:"ricky.jpg",
  }  
  it("should renders img src", () => {
     const wrapper=shallow(<CharacterInfo image={data.image}/>);
   });
  const imgSrc= wrapper.find("img").prop('src');
  expect(imgSrc).toBe("ricky.jpg");
})