Unit Testing with Mocks in Loosely Coupled Code

Writing reliable unit tests becomes difficult when your code relies on databases, external APIs, or complex third-party services. By decoupling your application logic and using mock objects, you can isolate your code and test it with complete confidence. This text-only course guides you through the foundational concepts of loose coupling and dependency injection, showing you how to substitute real dependencies with predictable mocks. You will learn to write clean, maintainable unit tests that execute quickly and reliably. What you will learn: Understand the core principles of loose coupling and testability; Configure mock objects to simulate successful responses and error states; Isolate external dependencies like databases and web services in your tests; Verify controller and service behaviors using NUnit and mocking libraries; Apply modern dependency injection patterns to make legacy code testable; Practice writing robust unit tests through structured written exercises and code analysis. You will start with the fundamental definitions of mocking, stubs, and fakes, then progress to practical testing scenarios. Through clear written explanations and detailed code snippets, you will learn to verify complex workflows without touching external systems. Designed for beginner-to-intermediate developers who understand basic programming concepts and want to master isolated unit testing. No prior experience with mocking frameworks is required. Start writing cleaner, faster, and more reliable unit tests today.