C# NUnit skill: NUnit unit testing practices for Claude Code

• Separate [ProjectName].Tests project, three packages, dotnet test

  Names the test project, lists the packages to reference and says to run tests with the .NET SDK command dotnet test.

  Runs code · Project Setup

• TestFixture, Test, Arrange-Act-Assert, MethodName_Scenario_ExpectedBehavior

  Covers the fixture and test attributes, setup and teardown attributes at test, class and assembly level, and the test naming pattern.

  Try: “Write NUnit tests for the Calculator class using the csharp-nunit rules.”

  Write · Test Structure

• One behaviour per test, independent and idempotent

  Keeps tests focused and free of dependencies on each other.

  Write · Standard Tests

• TestCase, TestCaseSource, Values, ValueSource, Random, Range, Combinatorial, Pairwise

  Lists the attributes to use for inline data, generated data and parameter combinations.

  Write · Data-Driven Tests

• Assert.That with constraints first, plus classic helpers

  Prefers the constraint model and also names Assert.AreEqual, CollectionAssert, StringAssert and Assert.Throws.

  Write · Assertions

• Moq or NSubstitute, interfaces, a DI container

  Suggests mocking dependencies through interfaces to isolate the unit under test.

  Write · Mocking and Isolation

• Category, Order, Author, Description, Explicit, Ignore

  Groups tests by feature and names the attributes for categories, order, ownership, descriptions and skipping.

  Write · Test Organization

Watch out for

• It edits your test project and runs tests

  The rules include creating a [ProjectName].Tests project and running dotnet test. Commit first so you can review the changes. github.com

• The plugin route adds an agent

  The csharp-dotnet-development plugin lists the expert-dotnet-software-engineer agent, whose tools include edit/editFiles, runCommands and runTests. Use the skills CLI tab to install only this skill. github.com