Gain insights into writing automated tests for React apps with Jest and React Testing Library. Learn about simulating user interactions and testing asynchronous parts to enhance app reliability.

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Jest - lesson 2

Jest with run command

Jest verbose

Jest coverage

Jest snapshot update

Jest react

Jest react-npm start

Jest react-copy

Jest react-C4

Jest react-C6

Jest react start c6

Jest - lesson 2-copy

Jest sandbox

Jest coverage-copy

Jest react-C4-start

Jest react-C4-start-5000

Jest react-npm start-5000

Jest react start c6-5000

Jest react-C8

The skills acquired from this course will allow you to write automated tests on your React app using Jest and React Testing Library, which are the de-facto testing tools for React. These tests will allow you to ship new versions of your app with confidence. The tests will also allow you to increase your release frequency, allowing you to get features to your customers quicker.

You will learn how to write robust tests that are resilient to breaking when code is improved and refactored, reducing maintenance costs.
The course will teach you how to simulate a user interacting with the app. Beyond that, it will also teach you how to robustly test asynchronous parts of the app.

Regular quizzes and exercises will reinforce knowledge throughout the course.

Testing React Apps with Jest and React Testing Library

# Testing an asynchronous function

We are going to write unit tests on the `getName` function below:

```javascript
export async function getName(id) {
  await wait(200);
  return names.length <= id ? null : names[id];
}
```

The `getName` function is asynchronous and returns a promise of either a name or `null`. It is asynchronous because of the call to a `wait` function, which uses `setTimeout` to resolve a promise after a certain number of milliseconds:

```javascript
function wait(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}
```

We also have an array containing two names:

```javascript
const names = ["Bill", "Jane"];
```

So, calling `getName` with `0` or `1` should return the relevant name from the `names` array.

Learn to write and test asynchronous code in this lesson.

Writing Asynchronous Tests

Introduction

Getting Started with Jest

Using Matchers

Getting Started with React Testing Library

React Testing Library Queries

Firing Events

Mocking

Testing Different Types of Components

Appendix

Writing Asynchronous Tests

Testing an asynchronous function