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

The starter project contains the same `ContactForm` component as the previous lesson. It also includes a half-implemented test that checks that the form is successfully submitted.

A copy of the code is in the code widget below. Click the **“Run”** button to run the tests.

module.exports = {
  presets: [
    ["@babel/preset-env", { targets: { node: "current" } }],
    ["@babel/preset-react", { runtime: "automatic" }],
  ],
};


React

Dart

GoJS React

Typescript React

Vue.js

# Filling in the Department field

There is a [`selectOptions`](https://testing-library.com/docs/ecosystem-user-event#selectoptionselement-values) function in the `user-event` package that simulates a user selecting one or more options in a `select` element.

Add the following line to the test in `ContactForm.test.js` after the **Name** field has been filled in:

```javascript
await user.selectOptions(
  screen.getByLabelText("Department"),
  screen.getByText("Support")
);
```

The `selectOptions` function receives the `select` element as its first parameter. Its second parameter is the option element being selected.

The above line in the test will simulate the user selecting the **Support** option in the **Department** field.

Run the test. The submitted data is output to the console. Does the test pass? What value is submitted in the **Department** field?

Learn how to simulate a user selecting an option in a select element.

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

Selecting an Option in a select Element

Filling in the Department field