#1 Using Jest This is how I use the Jest mock callback function to test the click event: import React from ‘react’; import { shallow } from ‘enzyme’; import Button from ‘./Button’; describe(‘Test Button component’, () => { it(‘Test click event’, () => { const mockCallBack = jest.fn(); const button = shallow((<Button onClick={mockCallBack}>Ok!</Button>)); button.find(‘button’).simulate(‘click’); expect(mockCallBack.mock.calls.length).toEqual(1); … Read more
I was able mock multiple calls and check the arguments this way: expect(mockFn.mock.calls).toEqual([ [arg1, arg2, …], // First call [arg1, arg2, …] // Second call ]); where mockFn is your mocked function name.
From Jest’s command-line options docs –verbose Display individual test results with the test suite hierarchy. So running jest –verbose Will print all the names in describe, it, test blocks. If you’re running tests with yarn, you can do yarn test –verbose If you’re running tests with npm, you can do npm test — –verbose If … Read more
toBeInTheDocument is not part of RTL. You need to install jest-dom to enable it. And then import it in your test files by: import ‘@testing-library/jest-dom’
I think you’re looking for: roots or modulePaths and moduleDirectories You can add both relative and absolute paths. I would make sure to include <rootDir> in the roots array, <rootDir> in the modulePaths array, and node_modules in the moduleDirectories array, unless you’ve got a good reason to exclude them. “jest”: { “roots”: [ “<rootDir>”, “/home/some/path/” … Read more
You can mock the module so it returns spies and import it into your test: import {navigationEnabled, guidanceEnabled} from ‘../../../magic/index’ jest.mock(‘../../../magic/index’, () => ({ navigationEnabled: jest.fn(), guidanceEnabled: jest.fn() })); Then later on you can change the actual implementation using mockImplementation navigationEnabled.mockImplementation(()=> true) //or navigationEnabled.mockReturnValueOnce(true); and in the next test navigationEnabled.mockImplementation(()=> false) //or navigationEnabled.mockReturnValueOnce(false);
Without using any other libraries: import * as axios from “axios”; // Mock out all top level functions, such as get, put, delete and post: jest.mock(“axios”); // … test(“good response”, () => { axios.get.mockImplementation(() => Promise.resolve({ data: {…} })); // … }); test(“bad response”, () => { axios.get.mockImplementation(() => Promise.reject({ … })); // … }); … Read more
Another possibility is that ts-jest is slow. There was an issue about that, and it was not completely resolved. There are various workarounds discussed. They consist of setting isolatedModules=true and also –maxWorkers=1. That is, in jest.config.js ‘use strict’; module.exports = { preset: ‘ts-jest’, testEnvironment: ‘node’, globals: { ‘ts-jest’: { isolatedModules: true } }, } and … Read more
This can be done with asymmetric matchers (introduced in Jest 18) expect(track).toHaveBeenCalledWith( expect.objectContaining({ “action”: “PublicationPage”, “category”: “PublicationPage”, “label”: “7”, “name”: “n/a” }) ) If you use jest-extended you can do something like expect(track).toHaveBeenCalledWith( expect.objectContaining({ “action”: “PublicationPage”, “category”: “PublicationPage”, “label”: “7”, “name”: “n/a”, “intervalInMilliseconds”: expect.toBeWithin(999, 1002) }) )
It fails cause x and y are different instances and not equal as in (x === y) === false. You can use toBe for primitives like strings, numbers or booleans for everything else use toEqual. For example x = 4 y = 4 x === y // true x = ‘someString’ y = ‘someString’ x … Read more