Basic React Test

NewComment.test.js

// https://reactjs.org/docs/testing-recipes.html

import React from 'react';
import ReactDOM from 'react-dom';
import { act } from 'react-dom/test-utils';
import NewComment from '../NewComment';

let div = document.createElement('div');

beforeEach(() => {
	div = document.createElement('div');
	document.body.appendChild(div);
});

afterEach(() => {
	ReactDOM.unmountComponentAtNode(div);
	div.remove();
	div = null;
});

describe('Popup for initial comment', () => {
	it('has a link to post', () => {
		act(() => {
			ReactDOM.render(<NewComment />, div);
		});
		const firstLink = div.querySelector('a');
		expect(firstLink.text).toEqual('post');
	});
});