Testing Kotlin Applications: From Unit Tests to E2E

Testing is an integral part of modern development, and Kotlin, with its concise syntax and powerful tools, provides excellent opportunities for creating high-quality tests. The book "Testing Kotlin Applications" is a comprehensive practical guide that will teach you how to write reliable, maintainable, and effective tests for projects of any scale.

What this book is about

The book covers the full testing cycle for Kotlin applications: from basic unit tests to complex end-to-end scenarios. You will start with the basics: setting up a test environment, working with JUnit 5 and KotlinTest (Kotest), and then move on to advanced topics:

• Unit testing — creating isolated tests for functions, classes, and methods using MockK and Mockito.
• Integration testing — verifying component interaction: databases, REST APIs, message queues.
• Testing with Spring Boot — context configuration, testing controllers, services, and repositories.
• Spek and Kotest — using alternative frameworks for writing readable and expressive tests.
• Testing coroutines — working with asynchronous code, testing suspend functions and Flow.
• E2E and UI testing — using Selenium, Ktor Client, and tools for testing Android applications.

Who this book is for

The book will be useful both for beginner developers just getting acquainted with testing and for experienced engineers looking to deepen their knowledge and master Kotlin specifics. The main audience:

• Kotlin developers (Java developers transitioning to Kotlin).
• QA engineers automating testing in Kotlin.
• Team Leads and architects implementing TDD and BDD culture in their teams.
• Students and course graduates wanting to gain practical skills.

What you will learn after reading

• How to properly structure tests and write readable scenarios.
• How to use mocks, stubs, and spies for test isolation.
• How to test asynchronous code and coroutines without headaches.
• How to integrate testing into a CI/CD pipeline.
• How to write tests for Android applications and server-side projects.
• How to measure code coverage and improve test quality.

The book contains many real-world examples, ready-to-use snippets, and practical exercises. The author shares best practices and pitfalls encountered along the way. After reading, you will be able to confidently cover your Kotlin projects with tests, reducing the number of bugs and increasing application stability.

"Testing Kotlin Applications" is not just theory, but a practical tool that should be on every Kotlin developer's desk. Order the book on PythonLib and start writing reliable code today!