Testing JavaScript (Node.js) Applications

In modern web development, code quality is not a luxury, but a necessity. The book "Testing JavaScript (Node.js) Applications" is a comprehensive guide that will help you master all aspects of testing server-side applications on Node.js. The author, Alexey Sokolov, shares practical experience and proven methodologies used in real production projects.

What is this book about?

The book covers the full testing cycle — from simple unit tests to complex end-to-end (E2E) scenarios. You will learn how to choose the right tools, write maintainable tests, and integrate them into a CI/CD pipeline. Special attention is given to common mistakes and how to avoid them.

Who is this book for?

• Junior developers who want to establish a proper testing culture from their first projects.
• Middle developers seeking to deepen their knowledge and master advanced techniques (mocks, stubs, snapshots).
• Team Leads planning to introduce testing into an existing project or improve current processes.
• QA engineers transitioning to server-side test automation.

What will you learn?

• The basics of unit testing using Jest and Mocha.
• How to test asynchronous code, promises, callbacks, and async/await.
• Principles of mocking external services (databases, APIs, file system).
• Integration testing with Supertest and Chai.
• E2E testing using Cypress and Playwright for Node.js.
• Setting up test environments, CI (GitHub Actions, GitLab CI).
• Code coverage, TDD and BDD approaches.

Why should you read it?

The book is written in a lively style with plenty of code examples. Each chapter contains practical exercises and checklists for review. You won't just read theory — you'll be able to apply the knowledge immediately in your own project. After reading, you will learn to write tests that truly protect your code from regressions and make development predictable.

This is not another dry documentation, but a roadmap that will take you from a beginner to a confident user of testing tools. It is ideally suited both for self-study and for team reading.