Testing Java Applications: From Unit Tests to Integration Scenarios

The book "Testing Java Applications" is a practical guide that will help you master the art of writing high-quality and reliable tests for Java projects. Whether you are working on microservices, monolithic applications, or web services, this book will be your reliable assistant in building an effective testing strategy.

What is this book about?

The book covers the full testing cycle of Java applications — from simple unit tests to complex integration scenarios. You will learn:

• Writing unit tests using JUnit 5 and TestNG, covering critical code sections
• Applying Mockito for isolating dependencies and creating mock objects
• Testing database interactions (H2, Testcontainers) and external APIs
• Integrating tests into CI/CD (Jenkins, GitHub Actions) for automatic execution on every commit
• Using TDD (Test-Driven Development) as a development methodology
• Performing load testing with JMeter and Gatling

Who is this book for?

The book is aimed at Java developers of Junior and Middle level who want to systematize their knowledge of testing and improve the quality of their code. It will be useful both for those just starting to write tests and for experienced professionals looking to delve into advanced techniques.

What will you learn?

• Fundamentals of unit testing: test structure, assertions, parameterized tests
• Working with mocks, stubs, and spies in Mockito
• Testing REST APIs with RestAssured and WebClient
• Integration testing of Spring Boot applications
• Code coverage and test quality analysis (JaCoCo, SonarQube)
• Test design patterns and anti-patterns

Each chapter contains numerous code examples, practical tasks, and ready-made templates that you can immediately apply in your projects. The author of the book — Alexey Sokolov, a senior developer with 10 years of experience in Java and test automation — shares real-world cases from commercial development.

Make testing an integral part of your development process — and your applications will become more stable, and your code cleaner and clearer. The book is available for download in PDF and EPUB formats on the PythonLib website.