Csharp Tunit

If you're writing C# unit tests with TUnit, this skill covers the practical stuff you need to know. It walks through TUnit's async assertion syntax like `await Assert.That(value).IsEqualTo(expected)`, shows how to use `[Arguments]` and `[MethodData]` for data-driven tests, and explains TUnit's lifecycle hooks from `[Before(Test)]` to `[After(Assembly)]`. The migration guide from xUnit is solid, mapping `[Fact]` to `[Test]` and explaining how TUnit's parallel execution works by default. TUnit feels like a modern take on unit testing with better fluent assertions, though the async-everywhere approach takes some getting used to.

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last updated: Aug 21, 2026

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Install

$ npx -y skills add github/awesome-copilot --skill csharp-tunit --agent claude-code

Installs into .claude/skills of the current project.

Files

TUnit Best Practices

Your goal is to help me write effective unit tests with TUnit, covering both standard and data-driven testing approaches.

Project Setup

Use a separate test project with naming convention [ProjectName].Tests
Reference TUnit package and TUnit.Assertions for fluent assertions
Create test classes that match the classes being tested (e.g., CalculatorTests for Calculator)
Use .NET SDK test commands: dotnet test for running tests
TUnit requires .NET 8.0 or higher

Test Structure

No test class attributes required (like xUnit/NUnit)
Use [Test] attribute for test methods (not [Fact] like xUnit)
Follow the Arrange-Act-Assert (AAA) pattern
Name tests using the pattern MethodName_Scenario_ExpectedBehavior
Use lifecycle hooks: [Before(Test)] for setup and [After(Test)] for teardown
Use [Before(Class)] and [After(Class)] for shared context between tests in a class
Use [Before(Assembly)] and [After(Assembly)] for shared context across test classes
TUnit supports advanced lifecycle hooks like [Before(TestSession)] and [After(TestSession)]