reactjs - 如何通过更改 useState 来测试 React Hooks 组件
问题描述
我有一个想用 Jest/Enzyme 测试的 React hooks 功能组件。我想根据 useState 值测试它的三次渲染行为。我似乎无法在网上找到任何示例。没有要模拟的“点击”——没有要模拟的 API 调用,因为最后,我仍然需要根据 useState 值进行测试。过去,使用类组件,我可以设置状态。用新的钩子,我不能。所以,基本上 - 我如何在模拟的 submitForm 函数中模拟异步等待,以便渲染正常运行?
这是我的组件:
import React, { useState } from 'react';
import { Redirect } from 'react-router-dom';
import Form from 'core/Form';
export const Parent = ({submitForm}) => {
const [formValues, setFormValues] = useState({});
const [redirect, setRedirect] = useState(false);
const handleChange = name => evt => {
setFormValues({ ...formValues, [name]: evt.target.value });
};
const onSubmit = async () => {
try {
const res = await submitForm(formValues);
if (res) setRedirect(true);
else setRedirect(false);
} catch (err) {
console.log('Submit error: ', err);
}
};
return redirect ? (
<Redirect push to={path} />
) : (
<Form onSubmit={onSubmit} values={formValues} onChange={handleChange} />
);
};
export default Parent;
到目前为止,这是我的测试:
import React from 'react';
import { shallow } from 'enzyme';
import { Redirect } from 'react-router-dom';
import Parent from './Parent';
import Form from 'core/Form';
let wrapper, props;
.
.
.
describe('<Parent /> rendering', () => {
beforeEach(() => {
props = createTestProps();
wrapper = shallow(<Parent {...props} />);
});
afterEach(() => {
jest.clearAllMocks();
});
const setState = jest.fn();
const useStateSpy = jest.spyOn(React, 'useState');
useStateSpy.mockImplementation(init => [init, setState]);
it('Should render 1 Form', () => {
expect(wrapper.find(Form)).toHaveLength(1);
});
it('renders Redirect after API call', () => {
setRedirect = jest.fn(() => false);
expect(wrapper.find(Redirect)).toHaveLength(1);
});
it('renders Form before API call', () => {
setRedirect = jest.fn(() => true);
expect(wrapper.find(Form)).toHaveLength(1);
});
});
解决方案
你不需要间谍useState
钩子。这意味着您不应该直接测试组件的这些钩子和方法。相反,您应该测试组件的行为(state
以及props
呈现的内容)
例如
index.tsx
:
import React, { useState } from 'react';
import { Redirect } from 'react-router-dom';
export const Form = ({ onSubmit, onChange, values }) => <form onSubmit={onSubmit}></form>;
const path = '/user';
export const Parent = ({ submitForm }) => {
const [formValues, setFormValues] = useState({});
const [redirect, setRedirect] = useState(false);
const handleChange = (name) => (evt) => {
setFormValues({ ...formValues, [name]: evt.target.value });
};
const onSubmit = async () => {
try {
const res = await submitForm(formValues);
if (res) setRedirect(true);
else setRedirect(false);
} catch (err) {
console.log('Submit error: ', err);
}
};
return redirect ? (
<Redirect push to={path} />
) : (
<Form onSubmit={onSubmit} values={formValues} onChange={handleChange} />
);
};
export default Parent;
index.test.tsx
:
import Parent, { Form } from './';
import React from 'react';
import { shallow } from 'enzyme';
import { Redirect } from 'react-router-dom';
import { act } from 'react-dom/test-utils';
const whenStable = async () =>
await act(async () => {
await new Promise((resolve) => setTimeout(resolve, 0));
});
describe('60137762', () => {
it('should render Form', () => {
const props = { submitForm: jest.fn() };
const wrapper = shallow(<Parent {...props}></Parent>);
expect(wrapper.find(Form)).toBeTruthy();
});
it('should handle submit and render Redirect', async () => {
const props = { submitForm: jest.fn().mockResolvedValueOnce(true) };
const wrapper = shallow(<Parent {...props}></Parent>);
wrapper.find(Form).simulate('submit');
await whenStable();
expect(props.submitForm).toBeCalledWith({});
expect(wrapper.find(Redirect)).toBeTruthy();
});
it('should handle submit and render Form', async () => {
const props = { submitForm: jest.fn().mockResolvedValueOnce(false) };
const wrapper = shallow(<Parent {...props}></Parent>);
wrapper.find(Form).simulate('submit');
await whenStable();
expect(props.submitForm).toBeCalledWith({});
expect(wrapper.find(Form)).toBeTruthy();
});
it('should handle error if submit failure', async () => {
const logSpy = jest.spyOn(console, 'log');
const mError = new Error('network');
const props = { submitForm: jest.fn().mockRejectedValueOnce(mError) };
const wrapper = shallow(<Parent {...props}></Parent>);
wrapper.find(Form).simulate('submit');
await whenStable();
expect(props.submitForm).toBeCalledWith({});
expect(logSpy).toHaveBeenCalledWith('Submit error: ', mError);
});
});
带有覆盖率报告的单元测试结果:
PASS stackoverflow/60137762/index.test.tsx
60137762
✓ should render Form (18ms)
✓ should handle submit and render Redirect (15ms)
✓ should handle submit and render Form (8ms)
✓ should handle error if submit failure (18ms)
console.log node_modules/jest-environment-enzyme/node_modules/jest-mock/build/index.js:866
Submit error: Error: network
at /Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/stackoverflow/60137762/index.test.tsx:39:20
at step (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/stackoverflow/60137762/index.test.tsx:44:23)
at Object.next (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/stackoverflow/60137762/index.test.tsx:25:53)
at /Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/stackoverflow/60137762/index.test.tsx:19:71
at new Promise (<anonymous>)
at Object.<anonymous>.__awaiter (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/stackoverflow/60137762/index.test.tsx:15:12)
at Object.<anonymous> (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/stackoverflow/60137762/index.test.tsx:37:47)
at Object.asyncJestTest (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/node_modules/jest-jasmine2/build/jasmineAsyncInstall.js:100:37)
at resolve (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/node_modules/jest-jasmine2/build/queueRunner.js:43:12)
at new Promise (<anonymous>)
at mapper (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/node_modules/jest-jasmine2/build/queueRunner.js:26:19)
at promise.then (/Users/ldu020/workspace/github.com/mrdulin/react-apollo-graphql-starter-kit/node_modules/jest-jasmine2/build/queueRunner.js:73:41)
-----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
-----------|---------|----------|---------|---------|-------------------
All files | 78.57 | 100 | 40 | 93.75 |
index.tsx | 78.57 | 100 | 40 | 93.75 | 12
-----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 4 passed, 4 total
Snapshots: 0 total
Time: 3.716s, estimated 5s
源代码:https ://github.com/mrdulin/react-apollo-graphql-starter-kit/tree/master/stackoverflow/60137762
推荐阅读
- c# - 在具有附加条件的子列表上应用日期过滤器c#Linq
- android - Android 11 更新对已获得的持久权限的影响
- pandas - 重塑数据框 pandas
- laravel - npm 错误!代码 ENOENT npm 错误!系统调用打开
- flutter - Flutter/Dart 语法 - 使用?
- c# - 如何以编程方式查看旧 Access 数据库的 VBA 代码?
- azure - Azure Frontdoor 为通配符域配置子域模式
- php - 使用响应中的变量查询 MySQL 数据库并显示
- laravel - 无法在 Apache 上使用 Laravel 8 的 Jetstream 获取登录/注册页面
- python - PyFPDF 生成垂直文本