Testing PHP Applications: From Unit Tests to Integration Checks

The book "Testing PHP Applications" is a practical guide that will help you master all aspects of testing web applications in PHP. Whether you work with frameworks (Laravel, Symfony, Yii) or write plain PHP, this book will become your desktop reference.

What is this book about?

The book covers the complete testing cycle for PHP applications — from writing simple unit tests to building complex integration checks and setting up continuous integration (CI/CD). The main focus is on practical examples and real-world development scenarios.

• Testing Basics — what tests are, types of testing, the test pyramid, why tests are important for business.
• PHPUnit — installation, configuration, writing test classes, assertion methods, data providers.
• Test-Driven Development (TDD) — the "red-green-refactor" methodology, how TDD accelerates development and improves architecture.
• Mock Objects and Stubs — dependency isolation, simulating external services, working with databases, APIs, and the file system.
• Integration Testing — testing databases, HTTP requests, sessions, cache, and queues.
• Testing Legacy Code — how to safely add tests to old projects, refactoring for testability.
• Automation and CI/CD — integration with GitHub Actions, GitLab CI, Jenkins, running tests on every commit.
• Advanced Topics — mutation testing, benchmarks, code coverage, static analysis (PHPStan, Psalm).

Who is this book for?

• Junior developers who want to learn how to write quality code and understand how tests work.
• Middle developers looking to deepen their knowledge in TDD, mocks, and integration tests.
• Team Leads and Architects planning to introduce a testing culture in their team.
• Technical Managers wanting to understand how to evaluate code quality and testing processes.

What will you learn?

• How to write tests that actually protect against bugs, not just "for show".
• How to properly isolate code using mock objects without creating brittle tests.
• How to test interactions with databases, external APIs, and the file system without side effects.
• How to set up automatic test execution on every push to the repository.
• How to refactor legacy code while covering it with tests without fear of breaking something.
• How to use code coverage to evaluate test quality without deceiving yourself with high percentages.

The book is written in a lively style and contains numerous code examples ready for use. All examples are available for download in the GitHub repository. After reading, you will be able to confidently implement testing in any PHP project and improve the quality of your code.