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Master Testing Library with ESLint Plugin

Master writing Testing Library tests with eslint-plugin-testing-library by anticipating common mistakes and following best practices

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On demand video

36 mins

Video Lessons

12 Videos

Course Instructor
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Mario Beltrán Alarcón

JS and OSS lover. Senior Software Engineer at Hotjar. Member of the Testing Library organization. Author of eslint-plugin-testing-library and octoclairvoyant.

How The Course Works


You can take the course from anywhere in the world, as long as you have a computer and an internet connection.


Learn at your own pace, whenever it's convenient for you. With no rigid schedule to worry about, you can take the course on your own terms.


Join a vibrant community of other students who are also learning with Master Testing Library with ESLint Plugin. Ask questions, get feedback and collaborate with others to take your skills to the next level.


Learn in a cohesive fashion that's easy to follow. With a clear progression from basic principles to advanced techniques, you'll grow stronger and more skilled with each module.

Course Overview

What you will learn
  • How to set up eslint-plugin-testing-library in your codebase

  • Getting ESLint feedback directly in your code editor and your terminal

  • ESLint advanced config for getting more granular control over the linting process

  • Better understanding of Testing Library errors

  • Anticipating common issues

  • Preventing flaky tests

  • Following best practices for Testing Library tests

  • Enforcing consistency across your tests

Testing Library is a great bunch of utils to write tests for your UI. It has become the favorite testing choice of many users since it encourages you to write more maintainable and reliable tests, encourages best practices, and doesn't focus on implementation but behavior.

However, testing your app correctly with Testing Library is not always straightforward. What query variant fits better for this situation? How should I check appearance/disappearance? What is the best way to handle async behaviors? Why am I seeing this particular error or warning? Why am I not getting the expected element? These are very typical questions while writing tests with Testing Library.

You are not alone! This course aims to help you master these situations with the assistance of eslint-plugin-testing-library: the official ESLint plugin for Testing Library.

The course will boost your Testing Library skills by using this plugin as a companion when writing tests. You will get instant feedback by linting your tests code, so you can follow best practices and anticipate common mistakes for Testing Library, as well as better understand its utils and their main purposes.

Get ready to say goodbye to flaky tests!

Our students work at

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Course Syllabus and Content

Module 1


1 Lesson

Module 2

Plugin features and set up

8 Lessons 22 Minutes

Module 3

Rules for following best practices

4 Lessons 14 Minutes

Module 4

Rules for preventing errors

0 Lessons

    Module 5

    Rules for style guidelines & Advanced Features

    0 Lessons

      Meet the Course Instructor

      Mario Beltrán Alarcón

      Mario Beltrán Alarcón

      Hi there! I'm Mario Beltrán, the instructor of this course and author of eslint-plugin-testing-library itself. I'm a Senior Software Engineer at Hotjar, and part of the Testing Library organization. Testing and OSS are my biggest passions, so this plugin is the perfect combination of both!

      During my last years as a Senior Engineer, I've been focused on the Developer Experience for other engineers working across many projects. This led me realizing common mistakes that developers tend to do when writing tests. This was the perfect opportunity for me to create this plugin, providing an automatic tool that will be your perfect companion when writing tests with Testing Library.

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      Frequently Asked Questions

      Who is this course for?

      This is a course about mastering Testing Library, so it's ideal for those with a base knowledge of writing tests who want to follow best practices, prevent common problems, and take advantage of the advanced Testing Library utils. Although the examples we will see are mostly written in React, the course is perfectly suitable for developers feeling confortable in plain DOM, Angular, or Vue

      Are there any prerequisites?

      Yes. The course assumes that you have a fair understanding of writing tests with Jest and Testing Library, and basic ESLint usage.

      What if I need help?

      You can ask us questions any time through the community Discord channel or by sending us a message.