Testing JavaScript (Node.js) Applications

The book "Testing JavaScript (Node.js) Applications" is a comprehensive guide that will help you master the art of writing quality tests for server-side and client-side Node.js applications. Whether you are building REST APIs, microservices, web applications, or chatbots, this book will give you the tools and techniques to ensure the reliability and stability of your code.

What is this book about?

The author systematically guides the reader from the basics of testing to advanced techniques. You will learn how to properly design tests, choose tools, and integrate testing into the development process. The book covers all key aspects:

• Unit testing — isolated testing of functions and modules using Jest and Mocha.
• Integration testing — verifying the interaction of components, databases, and external APIs.
• E2E testing — end-to-end scenarios using Playwright and Cypress.
• Mock and Stub — simulating dependencies, working with Sinon.js and built-in Jest mocks.
• Testing asynchronous code — promises, async/await, callbacks, events.
• Database testing — PostgreSQL, MongoDB, Redis in a test environment.
• CI/CD integration — automatic test execution in GitHub Actions and Jenkins.
• Code coverage — analyzing code coverage and improving quality.

Who is this book for?

This book will be useful for:

• Junior and Middle developers who want to write reliable code.
• Backend specialists working with Node.js and Express.
• Test automation engineers transitioning to JavaScript.
• Team leads and architects implementing a testing culture.
• Students and anyone studying modern web development.

What will you learn from this book?

• How to set up a test environment in 10 minutes.
• Why TDD (Test-Driven Development) speeds up development instead of slowing it down.
• How to test HTTP requests, WebSocket, and GraphQL.
• How to avoid common mistakes when writing tests.
• How to organize tests in large projects.
• How to use fixtures, factories, and patterns for test data.

Each chapter contains practical examples ready for use in real projects. All examples are available in the book's repository. After reading, you will be able to confidently add tests to any Node.js project and reduce the number of bugs in production.

"Testing JavaScript (Node.js) Applications" is not just theory, but a practical guide that will become your desktop reference. Start writing quality code today!