React 测试库 fireEvent.click 不工作

Question

我试图基本上只是更改一个计数器并显示该值已更改。 我正在使用getByTestId执行此操作，这可能是问题所在吗？

这是我的组件：

import React, { useState } from 'react';
import logo from './logo.svg';
import './App.css';

function App() {
    const [count, setCounter] = useState(0)
  return (
    <div className="App">
      <header className="App-header">
        <img src={logo} className="App-logo" alt="logo" />
                div
                <div
                    onClick={() => setCounter(prevCount => prevCount + 1)}
                    data-testid="addCount"
                >
                    +
                </div>
        <div data-testid="count">
          {count}
        </div>
                <div
                    onClick={() => setCounter(prevCount => prevCount - 1)}
                    data-testid="minusCount"
                >
                    -
                </div>
        <a
          className="App-link"
          href="https://reactjs.org"
          target="_blank"
          rel="noopener noreferrer"
        >
          Learn React
        </a>
      </header>
    </div>
  );
}

export default App;

这是我要运行的测试：

describe('State is managed correctly', () => {
    const { getByTestId } = render(<App />)
    const add = getByTestId(`addCount`)
    const count = getByTestId(`count`)

    it('count starts at 0', () => {
        expect(count).toHaveTextContent("0")
    })


 it('count added, value should be 1', () => {
        fireEvent.click(add)
        expect(count).toHaveTextContent("1") // error count is still 0
    })
})

Answer 1

看起来你不能像我希望的那样在 react-testing-library 中真正“管理” state。 从阅读文档看来，您也不应该这样做。

这是我的解决方案：

import React from 'react'
import { render, fireEvent, cleanup } from '@testing-library/react'

import App from '../src/App'

afterEach(cleanup)

describe('App component loads correctly', () => {
    const { container } = render(<App />)
    const { firstChild } = container
    test('renders correctly', () => {
        expect(container).toHaveTextContent(`Learn React`)
    })

    test('first child should contain class "App"', () => {
        expect(firstChild).toHaveClass(`App`)
    })
})

describe('State is managed correctly', () => {
    it('count starts at 0', () => {
        const { getByTestId } = render(<App />)
        const count = getByTestId(`count`)

        expect(count.innerHTML).toBe("0")
    })


 it('should add 1 to count', () => {
        const { getByTestId } = render(<App />)
        const count = getByTestId(`count`)
        const add = getByTestId(`addCount`)

        fireEvent.click(add)
        expect(count.innerHTML).toBe("1")
    })

    it('should minus 1 from count', () => {
        const { getByTestId } = render(<App />)
        const count = getByTestId(`count`)
        const minus = getByTestId(`minusCount`)

        fireEvent.click(minus)
        expect(count.innerHTML).toBe("-1")
    })
})

Answer 2

每次您需要验证某些东西时都需要重新运行查询。 const count = getByTestId('count')将count设置为初始值，因此您需要告诉它在触发事件后再次查找计数。

it('count added, value should be 1', () => {
  fireEvent.click(add)
  count = getByTestId('count')
  expect(count).toHaveTextContent("1") // error count is still 0
})

Answer 3

describe('State is managed correctly', () => {
const { getByTestId } = render(<App />)
const add = getByTestId(`addCount`)
const count = getByTestId(`count`)
const spy = jest.spyOn(add, 'click');
it('count starts at 0', () => {
    expect(count).toHaveTextContent("0")
})


 it('count added, value should be 1', () => {
        add.click();
        expect(count).toHaveTextContent("1") // error count is still 0
        spy.mockRestore();
    })
})

Answer 4

我正在使用testing-library ，就我而言，我有：

fireEvent(myElement, new MouseEvent('click'));

我添加了{bubbles: true}将其更改为：

fireEvent(myElement, new MouseEvent('click', { bubbles: true }));

它奏效了。 看来该事件应该冒泡才能起作用。 原生dispatchEvent发生同样的情况，需要气泡才能工作：

myElement.dispatchEvent(new Event("click", { bubbles: true }));