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Testing Libraries

By default @testing-library/react and @testing-library/jest-dom/extend-expect are added to the project. Some of their scripts are also automatically added to the setupFilesAfterEnv param for jest here.

  • @testing-library/react/cleanup-after-each - Will clean up the DOM after each test has ran.
  • @testing-library/jest-dom/extend-expect - Custom jest matchers that you can use to extend jest

If you want to override this you can create a file in the /app directory called jest.init.js and export whichever modules you want.


module.exports = ['@testing-library/react/cleanup-after-each', '@testing-library/jest-dom/extend-expect'];

More Info on Jest setupFilesAfterEnv here

Mocking API Responses

If your tests require data that's supplied by an external data source, you can use the jest.mock(...) function to automatically mock the modules used to supply the data.

Once you've mocked the module, you can provide a mockResolvedValue that returns the data you want to use for your test.


import React from 'react';
import axiosMock from 'axios';
import slotmachineResponse from '../data/slotmachine.json';


config: { polling: false },
data: slotmachineResponse,
status: 202,
statusText: 'Ok'

More info on using mocks in Jest here