Unit Testing with C#

MediumComputer Science13 chapters

Learn and practice unit testing in C#, from basics to advanced techniques. Learn to write trustworthy, maintainable tests, work with isolation frameworks, handle legacy code, and integrate testing into your organization.

What This Course Covers

Unit Testing with C# is structured into 13 chapters that build on each other progressively:

Chapter 1: The Basics of Unit Testing▼

Chapter 2: Your First Unit Tests with NUnit▼

Chapter 3: Breaking Dependencies with Stubs (Part 1)▼

Chapter 4: Breaking Dependencies with Stubs (Part 2)▼

Chapter 5: Interaction Testing with Mock Objects▼

Chapter 6: Isolation Frameworks▼

Chapter 7: Deep Dive into Isolation Frameworks▼

Chapter 8: Test Organization and Hierarchies▼

Chapter 9: The Pillars of Good Unit Tests - Trustworthy Tests▼

Chapter 10: Maintainable and Readable Tests▼

Chapter 11: Integrating Unit Testing into Organizations▼

Chapter 12: Working with Legacy Code▼

Chapter 13: Design and Testability▼

Each chapter combines interactive AI tutoring with hands-on examples. After you learn the material, Lambdio's spaced repetition algorithm schedules review sessions at optimal intervals — so you retain concepts and techniques long-term.

How to Study Unit Testing with C# on Lambdio

Lambdio's AI-powered platform adapts to how Computer Science courses are best learned. Here's our recommended approach:

Learning Mode

Standard Mode — for first-time learning of each chapter

Review Modes

Standard, Quiz — for spaced repetition reviews

Learning Priority

High Priority — controls how often the algorithm schedules reviews

Unit testing is a code-heavy, procedural subject that requires structured explanations, code examples, and hands-on practice writing test cases. Standard Mode delivers step-by-step tutorials with comprehension checks after each concept — ideal for mastering NUnit syntax, stub/mock patterns, and SOLID design principles. Socratic Mode is less suitable because unit testing involves precise C# syntax, assertion methods, and framework-specific attributes that are hard to discover through questioning alone. The Medium difficulty combined with the cumulative nature of the material makes High priority the right choice — the spaced repetition algorithm will schedule frequent reviews so testing patterns, isolation framework APIs, and design-for-testability concepts stay sharp. Use Quiz Mode for quick recall checks on terminology and syntax before moving to real-world testing scenarios.

Interactive Quiz

Test your knowledge with these sample questions from the course. Tap an answer to see if you're right:

Q1: What is the correct definition of a unit test?

Q2: Which NUnit attribute marks a class as containing tests?

Q3: What is a stub in unit testing?

Q4: What distinguishes a mock from a stub?

Q5: According to the one mock per test rule, how many mocks should a single test use?

Q6: What is the recommended naming pattern for test methods?

Q7: Which SOLID principle states that code should depend on abstractions rather than concretions?

What You'll Be Able to Do After This Course

✓Write automated unit tests using NUnit with proper test structure and assertions
✓Apply stubs to break dependencies on external systems and isolate code for testing
✓Use mock objects to verify correct interactions between components
✓Leverage isolation frameworks like NSubstitute to dynamically create test doubles
✓Organize test projects using hierarchies, base classes, and utility patterns
✓Write trustworthy tests that avoid logic, test one concern each, and remain isolated
✓Apply SOLID principles to design testable, maintainable C# code
✓Adopt strategies for introducing unit testing into existing codebases and organizations
✓Work effectively with legacy code by adding integration tests before refactoring
✓Differentiate between constrained and unconstrained isolation frameworks and choose appropriately