Testing TypeScript Applications: From Unit Tests to E2E

Modern web development is impossible without quality testing. The book "Testing TypeScript Applications" is a practical guide that will help you master all levels of testing: from simple unit tests to complex end-to-end scenarios. You will learn to write reliable, maintainable tests in TypeScript using the best tools and practices.

What is this book about?

The book covers the full testing cycle of TypeScript applications. You will start with the basics: setting up the test environment, choosing a framework (Jest, Vitest), writing your first tests. Then you will move on to more complex topics: mocks, stubs, testing asynchronous code, working with APIs and databases. Separate chapters are dedicated to integration testing and end-to-end (E2E) testing using Playwright and Cypress.

Who is this book for?

• Beginner developers who want to learn how to test their code from scratch.
• Experienced JavaScript/TypeScript developers striving to improve project quality.
• Frontend and backend specialists working with React, Angular, Vue, or Node.js.
• Tech leads and DevOps engineers implementing CI/CD and test automation.

What will you learn?

• How to set up Jest and Vitest for a TypeScript project.
• Rules for writing "clean" tests (FIRST principles).
• Testing React components, hooks, and services.
• Working with mocks, stubs, and spies (MockServiceWorker, Sinon).
• Integration testing of databases (TypeORM, Prisma).
• E2E testing with Playwright: recording, debugging, parallel execution.
• Code coverage and TDD (Test-Driven Development).
• Integrating testing into CI/CD pipelines (GitHub Actions, GitLab CI).

Why should you read this book?

The author shares real-world experience: you will learn not only "how to write tests" but also "how NOT to write tests." The book contains numerous examples, ready-made snippets, and practical exercises. After studying it, you will be able to confidently cover any TypeScript project with tests, reducing the number of bugs and speeding up development.

"Testing TypeScript Applications" is your reliable assistant in creating high-quality and stable code. Start testing the right way today!