@ttoss/test-utils

This package provides re-exports utilities for testing using Jest.

Installing the Package

We suggest installing the package at the root of your project:

yarn add -DW @ttoss/test-utils

How to Configure Your Project

You configure your project following the instructions in the Jest documentation. Add Jest to the root to your project:

yarn add -DW jest

If you're working with TypeScript, you'll also need to configure Babel to handle the transpilation of the ES6 code, TypeScript, and JSX.

yarn add --DW @ttoss/config

Add babel.config.js (touch babel.config.js) on the package folder:

const { babelConfig } = require('@ttoss/config');

module.exports = babelConfig();

You can read more about @ttoss/config here.

Using the Package

Matchers and Helpers

@ttoss/test-utils add the following matchers to Jest:

• @testing-library/jest-dom: custom matchers to test the state of the DOM.
• @emotion/jest: custom matchers to make more explicit assertions when testing libraries that use emotion.

If you use jsdom, you don't need to install jest-environment-jsdom, because the library already includes it.

React Testing Library

@ttoss/test-utils re-exports everything from @testing-library/react, like act, screen, and render.

If you want to set options to every test, you can use setOptions on Jest setup function. This way, all render calls will use the same default options, unless you override them.

import { setOptions } from '@ttoss/test-utils';

import AllProviders from './paht/to/AllProviders';

/**
 * Add global wrapper to React Testing Library `customRender`.
 */
setOptions({ wrapper: AllProviders });

User Interactions

@ttoss/test-utils re-exports userEvent from user event library.

For example, you write your tests like this:

import { render, screen, userEvent } from '@ttoss/test-utils';

import Component from './Component';

test('test with render', async () => {
  const user = userEvent.setup();

  render(<Component />);

  await user.click(screen.getByText('Increment'));

  expect(screen.getByText(1)).toBeInTheDocument();
});

Testing Hooks

@ttoss/test-utils re-exports renderHook from react-hooks-testing-library.

Example:

import { renderHook } from '@ttoss/test-utils';
import useCounter from './useCounter';

test('should use counter', () => {
  const { result } = renderHook(() => useCounter());

  expect(result.current.count).toBe(0);
  expect(typeof result.current.increment).toBe('function');
});

The setOptions also works for renderHook options.

Relay

It re-exports createMockEnvironment and MockPayloadGenerator from Relay test utils.

Example:

import {
  createMockEnvironment,
  MockPayloadGenerator,
} from '@ttoss/test-utils/relay';

// ...

Faker

It exports faker functions from faker. Example:

import { faker } from '@ttoss/test-utils/faker';

const randomName = faker.name.findName();
const randomEmail = faker.internet.email();
const randomCard = faker.helpers.createCard();

User Event

To render components it is recommended that you use a structure similar to the one below. If you need more information about this structure, you can consult this link here.

function setup(jsx: any) {
  return {
    user: userEvent.setup({
      // Use this key if you need to make async tests, like having clicks, write, paste, etc...
      // ref: https://testing-library.com/docs/user-event/options
      advanceTimers: () => Promise.resolve(),
    }),
    ...render(jsx),
  };
}

const onOpen = js.fn();

test('Testing something', async () => {
  const { user } = setup(<Example onOpen={onOpen} />);

  const buttonMenu = screen.getByLabelText('button-menu');
  await user.click(buttonMenu);

  expect(screen.getByLabelText('menu-container')).toBeTruthy();
});