wrolpi/app/src/App.test.js

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

Object.defineProperty(window, 'matchMedia', {
    writable: true, value: jest.fn().mockImplementation(query => ({
        matches: false, media: query, onchange: null, addListener: jest.fn(), // Deprecated
        removeListener: jest.fn(), // Deprecated
        addEventListener: jest.fn(), removeEventListener: jest.fn(), dispatchEvent: jest.fn(),
    })),
});

it('renders without crashing', () => {
    const div = document.createElement('div');
    ReactDOM.render(<App/>, div);
    ReactDOM.unmountComponentAtNode(div);
});