jest example for useeffect
Example: How to test useEffect in react testing library
import { List } from './';
import React from 'react';
import '@testing-library/jest-dom/extend-expect';
import { render, waitForElement } from '@testing-library/react';
describe('59892259', () => {
let originFetch;
beforeEach(() => {
originFetch = (global as any).fetch;
});
afterEach(() => {
(global as any).fetch = originFetch;
});
it('should pass', async () => {
const fakeResponse = { title: 'example text' };
const mRes = { json: jest.fn().mockResolvedValueOnce(fakeResponse) };
const mockedFetch = jest.fn().mockResolvedValueOnce(mRes as any);
(global as any).fetch = mockedFetch;
const { getByTestId } = render(<List></List>);
const div = await waitForElement(() => getByTestId('test'));
expect(div).toHaveTextContent('example text');
expect(mockedFetch).toBeCalledTimes(1);
expect(mRes.json).toBeCalledTimes(1);
});
});