Testing TypeScript Applications: From Unit Tests to E2E

The book "Testing TypeScript Applications" is a practical guide that will teach you step by step how to create reliable and maintainable tests for TypeScript projects. The author, Alexey Voronov, shares experience gained from testing large commercial and open-source projects and offers ready-made solutions for typical tasks.

What is this book about?

The book covers all levels of the testing pyramid:

• Unit testing — get to grips with Jest and Vitest, learn to test functions, classes, React and Angular components.
• Integration tests — learn how to verify module interactions, work with databases and external APIs.
• E2E testing — master Playwright and Cypress for full testing of user scenarios.
• Mock objects and stubs — understand when and how to use mocks, spies, and dependency substitution without pain.

Who is this book for?

• Frontend developers who want to write quality tests in TypeScript.
• Node.js backend developers looking to implement TDD in their projects.
• Team leads and technical managers seeking a systematic approach to testing.
• Beginning engineers who are just getting acquainted with TypeScript and want to build quality in from the start.

What will you learn from the book?

• How to set up a testing environment for TypeScript projects of any complexity.
• How to write readable and isolated unit tests using Jest and Vitest.
• How to test asynchronous code, promises, Observables, and timers.
• How to effectively mock HTTP requests, databases, and third-party services.
• How to implement TDD (Test-Driven Development) practices in everyday development.
• How to organize E2E testing with Playwright and Cypress for React, Angular, and Vue applications.
• How to measure code coverage and interpret the results.
• How to automate test execution in CI/CD (GitHub Actions, GitLab CI).

In the book, you will find dozens of real code examples that can be immediately applied to your projects. All examples are written in TypeScript using the most popular tools of 2024–2025.

The book is suitable for developers of any level — from beginners to experienced engineers wanting to systematize their knowledge. Start writing tests that truly protect your code from regressions and make development faster.