Testing C# (.NET) Applications: From Unit Tests to Integration Scenarios

The book "Testing C# (.NET) Applications" is a practical guide that will help you master all aspects of software testing on the .NET platform. Whether you are just starting your journey in development or already have experience, this book will be a reliable assistant in creating high-quality, reliable, and easily maintainable code.

What is this book about?

The book sequentially covers all key testing concepts and tools:

• Fundamentals of Unit Testing: You will learn what unit tests are, how to write them correctly, and why they are important. We will cover popular frameworks: NUnit and xUnit.
• Mock Objects and Isolation: Learn to use the Moq library to create stubs and simulate dependencies, allowing you to test code in isolation from external systems (databases, API, file system).
• Test-Driven Development (TDD): Master the TDD methodology with practical examples. You will see how writing tests before code helps design clean architecture and avoid regressions.
• Integration Testing: Learn how to verify the interaction of system components with real databases (Entity Framework), web services, and message queues.
• Automation and CI/CD: Learn to integrate tests into continuous integration pipelines (GitHub Actions, Azure DevOps) for automatic execution on every code change.
• Advanced Techniques: Covers parameterized tests, testing asynchronous code, working with logs, and code coverage.

Who is this book for?

The book is intended for:

• Junior C# developers who want to learn how to write quality tests and increase their market value.
• Middle developers seeking to systematize their knowledge and master advanced techniques such as TDD and integration testing.
• Team leads and architects interested in implementing a testing culture in their projects.

What will you learn?

• The correct Arrange-Act-Assert (AAA) structure for tests.
• How to avoid brittle and useless tests.
• SOLID principles in the context of testing.
• How to test ASP.NET Core applications (controllers, middleware).
• Working with test data and fixtures.
• Setting up Code Coverage and interpreting reports.

All examples in the book are written in the latest versions of C# and .NET (including .NET 6/7/8), are available for download, and can be immediately used in your projects. The book contains numerous practical exercises and checklists for self-assessment.

Make your code reliable and your development process predictable. Start testing correctly today!