OpenMediaCenter/src/setupTests.js

// jest-dom adds custom jest matchers for asserting on DOM nodes.
// allows you to do things like:
// expect(element).toHaveTextContent(/react/i)
// learn more: https://github.com/testing-library/jest-dom
import '@testing-library/jest-dom/extend-expect';

import {configure} from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

configure({adapter: new Adapter()});

/**
 * prepares fetch api for a virtual test call
 * @param response the response fetch should give you back
 * @returns {jest.Mock<any, any>} a jest mock function simulating a fetch
 */
global.prepareFetchApi = (response) => {
    const mockJsonPromise = Promise.resolve(response);
    const mockFetchPromise = Promise.resolve({
        json: () => mockJsonPromise,
    });
    return (jest.fn().mockImplementation(() => mockFetchPromise));
}

/**
 * prepares a failing virtual fetch api call
 * @returns {jest.Mock<any, any>} a jest moch function simulating a failing fetch call
 */
global.prepareFailingFetchApi = () => {
    const mockFetchPromise = Promise.reject("myreason");
    return (jest.fn().mockImplementation(() => mockFetchPromise));
}