我使用create-react-app引导了这个小项目，然后弹出，以便可以检查package.json。根据研究，我安装了酶和react-16适配器。我包括了package.json，以防万一。
我已经尝试了下面所有三个示例，每个示例实际上都单击了按钮，但是模拟中的期望都失败了。昨天迷失了整整一天，试图找出原因。我在做什么错或配置错误？
按钮组件：
import React from 'react'
class Button extends React.Component {
handleClick = (arg) => {
console.log('handleClick', arg)
}
render() {
return (
<button type="button" onClick={this.handleClick}>
Click Me
</button>
)
}
}
测试：
import React from 'react'
import Button from '../components/button'
import {shallow, configure} from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
configure({ adapter: new Adapter() });
test('onClick called', () => {
const wrapper = shallow(<Button />)
wrapper.instance().onClick = jest.fn()
wrapper.update()
wrapper.instance().handleClick('junk')
expect(wrapper.instance().onClick).toBeCalledWith('junk')
})
test('onClick called', () => {
const mockOnClick = jest.fn();
const wrapper = shallow(<Button onClick={mockOnClick} />)
wrapper.find('button').simulate('click', 'junk')
expect(mockOnClick.mock.calls.length).toEqual(1)
})
test('onClick called', () => {
const mockOnClick = jest.fn()
const wrapper = shallow(<Button onClick={mockOnClick}/>)
wrapper.find('button').at(0).simulate('click', 'junk')
expect(mockOnClick).toHaveBeenCalled()
})
测试控制台（首次测试）
console.log src/components/button.js:6
handleClick junk
● onClick called
expect(jest.fn()).toBeCalledWith(expected)
Expected mock function to have been called with:
["junk"]
But it was not called.
26 | wrapper.update()
27 | wrapper.instance().handleClick('junk')
> 28 | expect(wrapper.instance().onClick).toBeCalledWith('junk')
| ^
29 | })
30 |
31 | // test('onClick called', () => {
at Object.toBeCalledWith (src/__tests__/button-test.js:28:38)
测试控制台（第二项测试）
console.log src/components/button.js:6
handleClick junk
● onClick called
expect(received).toEqual(expected)
Expected value to equal:
1
Received:
0
33 | const wrapper = shallow(<Button onClick={mockOnClick} />)
34 | wrapper.find('button').simulate('click', 'junk')
> 35 | expect(mockOnClick.mock.calls.length).toEqual(1)
| ^
36 | })
37 |
38 | // test('onClick called', () => {
at Object.toEqual (src/__tests__/button-test.js:35:41)
测试控制台（第三项测试）
console.log src/components/button.js:6
handleClick junk
● onClick called
expect(jest.fn()).toHaveBeenCalled()
Expected mock function to have been called, but it was not called.
40 | const wrapper = shallow(<Button onClick={mockOnClick}/>)
41 | wrapper.find('button').at(0).simulate('click', 'junk') > 42 | expect(mockOnClick).toHaveBeenCalled()
| ^
43 | })
44 |
45 | // test('onClick called', () => {
at Object.toHaveBeenCalled (src/__tests__/button-test.js:42:23)
package.json
{
"name": "react-testing-demo",
"version": "0.1.0",
"private": true,
"dependencies": {
"@babel/core": "7.1.0",
"@svgr/webpack": "2.4.1",
"babel-core": "7.0.0-bridge.0",
"babel-eslint": "9.0.0",
"babel-jest": "23.6.0",
"babel-loader": "8.0.4",
"babel-plugin-named-asset-import": "^0.2.3",
"babel-preset-react-app": "^6.1.0",
"bfj": "6.1.1",
"case-sensitive-paths-webpack-plugin": "2.1.2",
"chalk": "2.4.1",
"css-loader": "1.0.0",
"dotenv": "6.0.0",
"dotenv-expand": "4.2.0",
"enzyme": "^3.7.0",
"enzyme-adapter-react-16": "^1.7.0",
"eslint": "5.6.0",
"eslint-config-react-app": "^3.0.5",
"eslint-loader": "2.1.1",
"eslint-plugin-flowtype": "2.50.1",
"eslint-plugin-import": "2.14.0",
"eslint-plugin-jsx-a11y": "6.1.2",
"eslint-plugin-react": "7.11.1",
"file-loader": "2.0.0",
"fork-ts-checker-webpack-plugin-alt": "0.4.14",
"fs-extra": "7.0.0",
"html-webpack-plugin": "4.0.0-alpha.2",
"identity-obj-proxy": "3.0.0",
"jest": "23.6.0",
"jest-pnp-resolver": "1.0.1",
"jest-resolve": "23.6.0",
"mini-css-extract-plugin": "0.4.3",
"optimize-css-assets-webpack-plugin": "5.0.1",
"pnp-webpack-plugin": "1.1.0",
"postcss-flexbugs-fixes": "4.1.0",
"postcss-loader": "3.0.0",
"postcss-preset-env": "6.0.6",
"postcss-safe-parser": "4.0.1",
"react": "^16.6.3",
"react-app-polyfill": "^0.1.3",
"react-dev-utils": "^6.1.1",
"react-dom": "^16.6.3",
"react-test-renderer": "^16.6.3",
"resolve": "1.8.1",
"sass-loader": "7.1.0",
"style-loader": "0.23.0",
"terser-webpack-plugin": "1.1.0",
"url-loader": "1.1.1",
"webpack": "4.19.1",
"webpack-dev-server": "3.1.9",
"webpack-manifest-plugin": "2.0.4",
"workbox-webpack-plugin": "3.6.3"
},
"scripts": {
"start": "node scripts/start.js",
"build": "node scripts/build.js",
"test": "node scripts/test.js"
},
"eslintConfig": {
"extends": "react-app"
},
"browserslist": [
">0.2%",
"not dead",
"not ie <= 11",
"not op_mini all"
],
"jest": {
"collectCoverageFrom": [
"src/**/*.{js,jsx,ts,tsx}",
"!src/**/*.d.ts"
],
"resolver": "jest-pnp-resolver",
"setupFiles": [
"react-app-polyfill/jsdom"
],
"testMatch": [
"<rootDir>/src/**/__tests__/**/*.{js,jsx,ts,tsx}",
"<rootDir>/src/**/?(*.)(spec|test).{js,jsx,ts,tsx}"
],
"testEnvironment": "jsdom",
"testURL": "http://localhost",
"transform": {
"^.+\\.(js|jsx|ts|tsx)$": "<rootDir>/node_modules/babel-jest",
"^.+\\.css$": "<rootDir>/config/jest/cssTransform.js",
"^(?!.*\\.(js|jsx|ts|tsx|css|json)$)": "<rootDir>/config/jest/fileTransform.js"
},
"transformIgnorePatterns": [
"[/\\\\]node_modules[/\\\\].+\\.(js|jsx|ts|tsx)$",
"^.+\\.module\\.(css|sass|scss)$"
],
"moduleNameMapper": {
"^react-native$": "react-native-web",
"^.+\\.module\\.(css|sass|scss)$": "identity-obj-proxy"
},
"moduleFileExtensions": [
"web.js",
"js",
"web.ts",
"ts",
"web.tsx",
"tsx",
"json",
"web.jsx",
"jsx",
"node"
]
},
"babel": {
"presets": [
"react-app"
]
}
}
答案 0 :(得分：2)
该按钮的onclick处理程序设置为this.handleClick。尝试更改此内容以在事实发生后更改此内容是徒劳的。
<button type="button" onClick={this.handleClick}>
Click Me
</button>
第一个测试变体模拟onClick组件的Button方法；这不是Button组件的已定义方法。
// 1.
test('onClick called', () => {
const wrapper = shallow(<Button />)
wrapper.instance().onClick = jest.fn()
wrapper.update()
wrapper.instance().handleClick('junk')
expect(wrapper.instance().onClick).toBeCalledWith('junk')
})
第二个和第三个变体将onClick道具转发到Button组件； Button组件不会公开onClick属性。
//2.
test('onClick called', () => {
const mockOnClick = jest.fn();
const wrapper = shallow(<Button onClick={mockOnClick} />)
wrapper.find('button').simulate('click', 'junk')
expect(mockOnClick.mock.calls.length).toEqual(1)
})
//3.
test('onClick called', () => {
const mockOnClick = jest.fn()
const wrapper = shallow(<Button onClick={mockOnClick}/>)
wrapper.find('button').at(0).simulate('click', 'junk')
expect(mockOnClick).toHaveBeenCalled()
})
由于您要测试单击按钮时是否调用handleClick，因此可以在闭包中调用this.handleClick。
这使得在调用onclick处理程序时，它将在this.handleClick中调用该方法。
<button type="button" onClick={evt => this.handleClick(evt)}>
Click Me
</button>
第一个测试变体适用于上述更改。
当暴露onClick组件中的Button属性时，其余测试变体将成功运行。
class Button extends React.Component {
handleClick = (arg) => {
this.props.onClick(arg);
console.log('handleClick', arg)
}
//...
}
Button.propTypes = {
onClick: PropTypes.func.isRequired
}