xunit

name	xunit
description	Writes unit tests with xUnit framework across 30 test projects. Use when: writing new tests, adding test coverage, creating integration tests, setting up test fixtures, or debugging test failures.
allowed-tools	Read, Edit, Write, Glob, Grep, Bash, mcp__context7__resolve-library-id, mcp__context7__query-docs

xUnit Skill

xUnit is the testing framework to use. Tests use Shouldly for readable assertions and Nsubstitute for mocking. All tests follow strict MethodName_Scenario_ExpectedBehavior naming.

Quick Start

Unit Test Structure

public class WalletManagerTests
{
    private readonly Mock<IRepository<Wallet>> _mockRepository;
    private readonly WalletManager _sut;

    public WalletManagerTests()
    {
        _mockRepository = new Mock<IRepository<Wallet>>();
        _sut = new WalletManager(_mockRepository.Object);
    }

    [Fact]
    public async Task CreateAsync_ValidWallet_ReturnsSuccess()
    {
        // Arrange
        var wallet = new Wallet { Name = "Test" };
        _mockRepository.Setup(r => r.AddAsync(wallet)).ReturnsAsync(wallet);

        // Act
        var result = await _sut.CreateAsync(wallet);

        // Assert
        result.IsSuccess.Should().BeTrue();
        result.Value.Should().Be(wallet);
    }
}

Theory with InlineData

[Theory]
[InlineData(12)]
[InlineData(15)]
[InlineData(18)]
[InlineData(21)]
[InlineData(24)]
public void GenerateMnemonic_ValidWordCount_ReturnsCorrectLength(int wordCount)
{
    var result = _keyManager.GenerateMnemonic(wordCount);

    result.IsSuccess.Should().BeTrue();
    result.Value!.Split(' ').Should().HaveCount(wordCount);
}

Key Concepts

Concept	Usage	Example
[Fact]	Single test case	[Fact] public void Method_Test() {}
[Theory]	Parameterized tests	[Theory] [InlineData(1)] public void Method(int x) {}
IClassFixture<T>	Per-class shared state	class Tests : IClassFixture<DbFixture>
ICollectionFixture<T>	Cross-class shared state	[Collection("Db")] class Tests
IAsyncLifetime	Async setup/teardown	Task InitializeAsync(), Task DisposeAsync()

Common Patterns

Exception Testing

[Fact]
public void Constructor_NullRepository_ThrowsArgumentNullException()
{
    var act = () => new WalletManager(null!);

    act.Should().Throw<ArgumentNullException>()
        .WithParameterName("repository");
}

[Fact]
public async Task ProcessAsync_InvalidData_ThrowsWithMessage()
{
    var exception = await Assert.ThrowsAsync<InvalidOperationException>(
        () => _processor.ProcessAsync(invalidContext));

    exception.Message.Should().Contain("validation failed");
}

Async Test Pattern

[Fact]
public async Task ExecuteAsync_ValidBlueprint_CompletesSuccessfully()
{
    // Arrange
    var blueprint = CreateTestBlueprint();

    // Act
    var result = await _engine.ExecuteAsync(blueprint);

    // Assert
    result.Success.Should().BeTrue();
    result.ProcessedData.Should().ContainKey("output");
}

See Also

• patterns - Test patterns and anti-patterns
• workflows - Test workflows and fixtures

Related Skills

• See the dotnet-testing-nsubstitute-mocking skill for mocking dependencies
• See the entity-framework skill for database testing with InMemory provider

Documentation Resources

Fetch latest xUnit documentation with Context7.

How to use Context7:

1. Use mcp__context7__resolve-library-id to search for "xunit"
2. Query with mcp__context7__query-docs using the resolved library ID

Library ID: /xunit/xunit.net (875 code snippets, High reputation)

Recommended Queries:

• "xUnit Theory InlineData patterns"
• "IClassFixture ICollectionFixture shared context"
• "IAsyncLifetime async setup teardown"
• "xUnit parallel test execution configuration"