PlugWiki

csharp-xunit Skill for Claude: What It Does and How to Install It

Makes Claude write C# unit tests with xUnit, including Fact tests, Theory data-driven tests, fixtures and mocks.

Installs
10.4K
on skills.sh
Stars
40.7K
on GitHub
Updated
Oct 2026
last repo commit

This skill is a short xUnit rulebook for Claude, from the community awesome-copilot collection. It sets the project layout ([ProjectName].Tests), the Arrange-Act-Assert pattern and the MethodName_Scenario_ExpectedBehavior naming.

It covers [Fact] and [Theory] tests with [InlineData], [MemberData] and [ClassData], the Assert methods, fixtures, mocking with Moq or NSubstitute, and [Trait] categories. It bundles one file and no scripts. SKILL.md names dotnet test as the way to run tests.

Good for

  • C# and .NET developers adding unit tests
  • Teams standardising test naming and structure
  • Developers moving from MSTest or NUnit to xUnit

Install csharp-xunit

Claude Code

  1. 1

    Copy this prompt.

    Install the csharp-xunit skill in Claude Code. Run this command:

npx skills add https://github.com/github/awesome-copilot --skill csharp-xunit

Then check that it loaded and tell me how to use it.
  2. 2

    Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

From its listing on skills.sh. Source.

What's in the skill

When it loads

Get best practices for XUnit unit testing, including data-driven tests

Sections in SKILL.md

  1. Project Setup
  2. Test Structure
  3. Standard Tests
  4. Data-Driven Tests
  5. Assertions
  6. Mocking and Isolation
  7. Test Organization

Key facts

Author
GitHub (awesome-copilot community collection)
License
MIT (repo license from GitHub; SKILL.md states none)
Installs on skills.sh
10,375 (Nov 2, 2026)
GitHub stars
40,666 for the whole github/awesome-copilot repo (Nov 2, 2026)
Last repo commit
Oct 30, 2026
What it includes
1 file: SKILL.md (no scripts or references)
Needs
A .NET project with the .NET SDK. The skill names Microsoft.NET.Test.Sdk, xunit and xunit.runner.visualstudio as packages to reference

What it includes

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

    Names the test project, the packages to reference and the test class naming, such as CalculatorTests for Calculator.

    Read · Project Setup

  • [Fact], Arrange-Act-Assert, constructor setup, fixtures

    Tells Claude to use constructors for setup, IDisposable for teardown, IClassFixture for shared context in a class and ICollectionFixture across classes.

    Try: “Write xUnit tests for the OrderService class.”

    Write · Test Structure

  • One behavior per test, independent and repeatable

    Keeps tests focused with only the assertions needed.

    Write · Standard Tests

  • [Theory] with InlineData, MemberData, ClassData

    Uses Theory with a data attribute, or a custom DataAttribute, and meaningful parameter names.

    Write · Data-Driven Tests

  • Assert.Equal, Same, True, Contains, Matches, Throws

    Lists which Assert method to use for values, references, collections, regex and exceptions, including ThrowsAsync.

    Read · Assertions

  • Moq or NSubstitute, interfaces, DI container

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

    Read · Mocking and Isolation

  • Trait categories, collection fixtures, ITestOutputHelper, Skip

    Groups tests by feature, adds diagnostics output and skips tests with a reason.

    Read · Test Organization

From the official docs

Permissions

Low risk

Claude writes test files and may run dotnet test, which executes your project code. Use it in a project you trust and review the new tests.

What it can do

  • Read your data
  • Create and change things
  • Delete things
  • Read-only mode

Watch out for

  • It may run dotnet test

    Running tests executes your project code and any test setup it contains. Check the command before you approve it. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details
Turning on read-onlyNo read-only mode. Use version control.
Sign-in and keysSKILL.md mentions no account or key.
Scopes

  • Claude can write xUnit test files in your project

  • SKILL.md names dotnet test for running tests, which runs your own test code

Questions

What does the csharp-xunit skill do?

It gives Claude a set of xUnit rules for C#. Claude uses them to write [Fact] and [Theory] tests with a clear structure, naming and assertions.

How do I install csharp-xunit?

Use the install box at the top of this page. The skill is one SKILL.md file with no scripts.

Does it cover MSTest or NUnit?

No. It is written for xUnit, and mentions MSTest and NUnit once, to say xUnit needs no test class attributes. The same repo has separate C# skills for those frameworks.

Is it part of a plugin?

Yes, in the Copilot CLI plugin csharp-dotnet-development, whose plugin.json lists 9 skills and 1 agent. The awesome-copilot README documents plugin installs with copilot plugin install <plugin-name>@awesome-copilot. For Claude Code, use the install box.

Does it run my tests?

SKILL.md names dotnet test as the command for running tests, so Claude may run it in your project. That executes your test code, so use a project you trust.

Is it safe?

It bundles no scripts. Claude writes test files in your project and may run dotnet test, which runs your own code. The README warns that awesome-copilot customizations come from third-party developers and should be inspected before installing.

Information

updated Nov 2, 2026

Repository
github/awesome-copilot
Folder
skills/csharp-xunit

github/awesome-copilotskills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 2
  1. csharp-xunit SKILL.md · github.com
  2. github/awesome-copilot README · github.com

Updated Nov 2, 2026.