jest mock useeffect return code example
Example 1: 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);
});
});
Example 2: how to test useeffect with enzyme
import React from "react";
import { render, unmountComponentAtNode } from "react-dom";
import { act } from "react-dom/test-utils";
import Contact from "./contact";
import MockedMap from "./map";
jest.mock("./map", () => {
return function DummyMap(props) {
return (
<p>A dummy map.</p>
);
};
});
it("should render contact information", () => {
const center = { lat: 0, long: 0 };
act(() => {
render(
<Contact
name="Joni Baez"
email="[email protected]"
site="http://test.com"
center={center}
/>,
container
);
});
});