C# Tutorial: Testing
Unit testing with xUnit, assertions, test organisation, and mocking basics.
Test-driven development
C# uses test frameworks like xUnit or MSTest. xUnit is the modern choice for .NET.
Good tests follow the AAA pattern: Arrange (set up), Act (do the thing), Assert (verify the result).
What you'll learn in this C# testing tutorial
This interactive C# tutorial has 8 hands-on exercises. Estimated time: 18 minutes.
- Your first test — In C# tests, use [Fact] for a single test case.
- Multiple test cases — In xUnit, `[Theory]` with `[InlineData]` runs a test with multiple input sets.
- Testing exceptions — Verify that code throws the right exception.
- Assert methods — Common assertion patterns.
- Arrange-Act-Assert pattern — Structure tests clearly with AAA.
- Test-driven development — Write the test first, watch it fail, then implement.
- Parameterised testing with loops — Test many edge cases systematically.
- Testing private logic via public interface — Test through the public interface, not by accessing private fields.
C# Testing concepts covered
- Test-driven development