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Table of Contents

• The problem
• This solution
• Example
• Installation
• Examples
• Other Solutions
• Guiding Principles
• Contributors
• Issues
  • 🐛 Bugs
  • 💡 Feature Requests
• LICENSE

The problem

You want to write maintainable tests for your Inferno components. As a part of this goal, you want your tests to avoid including implementation details of your components and rather focus on making your tests give you the confidence for which they are intended. As part of this, you want your testbase to be maintainable in the long run so refactors of your components (changes to implementation but not functionality) don't break your tests and slow you and your team down.

This solution

The inferno-testing-library is a very lightweight solution for testing Inferno components. It provides light utility functions on top of Inferno, in a way that encourages better testing practices. Its primary guiding principle is:

The more your tests resemble the way your software is used, the more confidence they can give you.

Example

// __tests__/fetch.js
import {
  render,
  fireEvent,
  cleanup,
  waitForElement,
} from 'inferno-testing-library'
// this adds custom jest matchers from jest-dom
import 'jest-dom/extend-expect'

// the mock lives in a __mocks__ directory
// to know more about manual mocks, access: https://jestjs.io/docs/en/manual-mocks
import axiosMock from 'axios'
import Fetch from '../fetch' // see the tests for a full implementation

// automatically unmount and cleanup DOM after the test is finished.
afterEach(cleanup)

test('Fetch makes an API call and displays the greeting when load-greeting is clicked', async () => {
  // Arrange
  axiosMock.get.mockResolvedValueOnce({data: {greeting: 'hello there'}})
  const url = '/greeting'
  const {getByText, getByTestId, container, asFragment} = render(
    <Fetch url={url} />,
  )

  // Act
  fireEvent.click(getByText(/load greeting/i))

  // Let's wait until our mocked `get` request promise resolves and
  // the component calls setState and re-renders.
  // getByTestId throws an error if it cannot find an element with the given ID
  // and waitForElement will wait until the callback doesn't throw an error
  const greetingTextNode = await waitForElement(() =>
    getByTestId('greeting-text'),
  )

  // Assert
  expect(axiosMock.get).toHaveBeenCalledTimes(1)
  expect(axiosMock.get).toHaveBeenCalledWith(url)
  expect(getByTestId('greeting-text')).toHaveTextContent('hello there')
  expect(getByTestId('ok-button')).toHaveAttribute('disabled')
  // snapshots work great with regular DOM nodes!
  expect(container.firstChild).toMatchSnapshot()
  // you can also use get a `DocumentFragment`, which is useful if you want to compare nodes across render
  expect(asFragment()).toMatchSnapshot()
})

Installation

This module is distributed via npm which is bundled with node and should be installed as one of your project's devDependencies:

npm install --save-dev inferno-testing-library

This library has peerDependencies listings for inferno and inferno-create-element.

You may also be interested in installing jest-dom so you can use the custom jest matchers.

Docs

Examples

We're in the process of moving examples to the docs site

You'll find runnable examples of testing with different libraries in the examples directory. Some included are:

• inferno-redux
• inferno-router
• inferno-context

You can also find inferno-testing-library examples at inferno-testing-examples.com.

Other Solutions

In preparing this project, I tweeted about it and Sune Simonsen took up the challenge. We had different ideas of what to include in the library, so I decided to create this one instead.

Guiding Principles

The more your tests resemble the way your software is used, the more confidence they can give you.

We try to only expose methods and utilities that encourage you to write tests that closely resemble how your inferno components are used.

Utilities are included in this project based on the following guiding principles:

1. If it relates to rendering components, it deals with DOM nodes rather than component instances, nor should it encourage dealing with component instances.
2. It should be generally useful for testing individual Inferno components or full Inferno applications. While this library is focused on inferno-dom, utilities could be included even if they don't directly relate to inferno-dom.
3. Utility implementations and APIs should be simple and flexible.

At the end of the day, what we want is for this library to be pretty light-weight, simple, and understandable.

Contributors

All people on the main project react-testing-library

This project follows the all-contributors specification. Contributions of any kind welcome!

Issues

Looking to contribute? Look for the Good First Issue label.

🐛 Bugs

Please file an issue for bugs, missing documentation, or unexpected behavior.

See Bugs

💡 Feature Requests

Please file an issue to suggest new features. Vote on feature requests by adding a 👍. This helps maintainers prioritize what to work on.

See Feature Requests

LICENSE

MIT