Update: All this info and more has now been added to the Jest docs in a new guide, “ES6 Class Mocks.” Full disclosure: I wrote it. 🙂 The key to mocking ES6 classes is knowing that an ES6 class is a function. Therefore, the mock must also be a function. Call jest.mock(‘./mocked-class.js’);, and also import … Read more
I think this question has not been answered with enough details! Snapshot testing is based on history of your previous tests. When you first run a snapshot test it creates a text file including the textual render of your component tree. For example the following test: import React from ‘react’; import renderer from ‘react-test-renderer’; it(‘renders … Read more
if you have a label like with Radio Component of Material-ui, you could use: const labelRadio: HTMLInputElement = getByLabelText(‘Label of Radio’); expect(labelRadio.checked).toEqual(false); fireEvent.click(labelRadio); expect(androidRadio.checked).toEqual(true); or you can add https://github.com/testing-library/jest-dom matchers and check it in this way: expect(getByLabelText(‘Label of Radio’)).not.toBeChecked(); fireEvent.click(labelRadio); expect(getByLabelText(‘Label of Radio’)).toBeChecked();
The underlying problem is How to test console.log? The short answer is that you should replace the console.{method} for the duration of the test. The common approach is to use spies. In this particular case, you might want to use stubs to prevent the output. Here is an example implementation using Sinon.js (Sinon.js provides standalone … Read more
You can wrap your component in the test with the StaticRouter to get the router context into your component: import React from ‘react’; import renderer from ‘react-test-renderer’; import { Link } from ‘react-router-dom’; import { StaticRouter } from ‘react-router’ test(‘Link matches snapshot’, () => { const component = renderer.create( <StaticRouter location=”someLocation” context={context}> <Link to=”#” /> … Read more
The first argument of jest.mock(…) must be a module path: jest.mock(‘../../src/utils’); because the utils module is your code, not a 3rd lib, so you must learn manual mock of jest: https://facebook.github.io/jest/docs/en/manual-mocks.html if you had this file: src/utils.js you can mock it by creating a file: src/__mocks__/utils.js content of this file is the replication of the … Read more
Jest describe.each expects an array of arrays in the first parameter. If you pass in a 1D array, internally it will be mapped to an array of arrays (i.e. passing [1, 2, 3] as first parameter would be converted to [[1], [2], [3]]). Each one of the arrays inside of the array is used as … Read more
This is the most semantic way I’ve found. It is even just a translation of the test name. describe(“Foo.bar()”, () => { test(“Should not throw”, async () => { await expect(new Foo().bar()).resolves.not.toThrow(); }); });
Jest offers a testTimeout configuration option you can add to your package.json: “jest”: { “testTimeout”: 15000, }
It can be a Jest configuration issue. I solved forcing “node” as jest environment in package.json: “jest”: { “testEnvironment”: “node” } see docs: https://facebook.github.io/jest/docs/configuration.html#testenvironment-string