---
name: xunit-skill-1af7c24432dc
description: >
  Generates xUnit.net tests in C#. Covers Fact/Theory, constructor injection,
  IClassFixture, and FluentAssertions. Use when user mentions "xUnit",
  "[Fact]", "[Theory]", "Assert.Equal", "C# xUnit". Triggers on: "xUnit",
  "[Fact]", "[Theory]", "Assert.Equal C#", "xUnit.net".
languages:
  - C#
category: unit-testing
license: MIT
metadata:
  author: TestMu AI
  version: "1.0"
---

# xUnit.net Testing Skill

## Core Patterns

### Basic Test

```csharp
using Xunit;

public class CalculatorTests
{
    private readonly Calculator _calc = new();

    [Fact]
    public void Add_TwoPositiveNumbers_ReturnsSum()
    {
        Assert.Equal(5, _calc.Add(2, 3));
    }

    [Fact]
    public void Divide_ByZero_ThrowsException()
    {
        Assert.Throws<DivideByZeroException>(() => _calc.Divide(10, 0));
    }
}
```

### Theory (Parameterized)

```csharp
[Theory]
[InlineData(2, 3, 5)]
[InlineData(-1, 1, 0)]
[InlineData(0, 0, 0)]
public void Add_ReturnsCorrectSum(int a, int b, int expected)
{
    Assert.Equal(expected, _calc.Add(a, b));
}

[Theory]
[MemberData(nameof(GetTestData))]
public void Add_WithMemberData(int a, int b, int expected)
{
    Assert.Equal(expected, _calc.Add(a, b));
}

public static IEnumerable<object[]> GetTestData()
{
    yield return new object[] { 1, 2, 3 };
    yield return new object[] { -1, -1, -2 };
}

[Theory]
[ClassData(typeof(CalculatorTestData))]
public void Add_WithClassData(int a, int b, int expected)
{
    Assert.Equal(expected, _calc.Add(a, b));
}
```

### Assertions

```csharp
Assert.Equal(expected, actual);
Assert.NotEqual(unexpected, actual);
Assert.True(condition);
Assert.False(condition);
Assert.Null(obj);
Assert.NotNull(obj);
Assert.Contains("sub", str);
Assert.DoesNotContain("x", str);
Assert.Empty(collection);
Assert.Single(collection);
Assert.Collection(list,
    item => Assert.Equal("first", item),
    item => Assert.Equal("second", item));
Assert.IsType<MyClass>(obj);
var ex = Assert.Throws<ArgumentException>(() => Method());
Assert.Equal("message", ex.Message);
Assert.InRange(value, 1, 10);
```

### Shared Context (IClassFixture)

```csharp
public class DatabaseFixture : IDisposable
{
    public DbConnection Connection { get; }
    public DatabaseFixture() { Connection = new DbConnection("test"); }
    public void Dispose() { Connection.Close(); }
}

public class UserTests : IClassFixture<DatabaseFixture>
{
    private readonly DatabaseFixture _fixture;
    public UserTests(DatabaseFixture fixture) { _fixture = fixture; }

    [Fact]
    public void GetUser_ReturnsUser()
    {
        var user = _fixture.Connection.Query<User>("SELECT * FROM Users LIMIT 1");
        Assert.NotNull(user);
    }
}
```

### Constructor/Dispose (Per-Test Setup)

```csharp
public class MyTests : IDisposable
{
    private readonly MyService _service;
    public MyTests() { _service = new MyService(); }   // SetUp
    public void Dispose() { _service.Cleanup(); }       // TearDown

    [Fact]
    public void TestSomething() { Assert.True(_service.IsReady); }
}
```

### Anti-Patterns

| Bad | Good | Why |
|-----|------|-----|
| `[Fact]` with parameters | `[Theory]` + `[InlineData]` | xUnit convention |
| Static state | `IClassFixture` | Test isolation |
| No `IDisposable` | Implement for cleanup | Resource management |

## Setup: `dotnet add package xunit xunit.runner.visualstudio Microsoft.NET.Test.Sdk`
## Run: `dotnet test` or `dotnet test --filter "FullyQualifiedName~Calculator"`

## Deep Patterns

For advanced patterns, debugging guides, CI/CD integration, and best practices,
see `reference/playbook.md`.


---
Source attribution: LambdaTest
Original project: https://github.com/LambdaTest/agent-skills
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Mega AI Hub.

## Upstream license notice

MIT License

Copyright (c) 2026 Gabriel Moreira

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Mega AI Hub resource metadata

Creator / publisher: LambdaTest
Original project: https://github.com/LambdaTest/agent-skills
Attribution basis: Upstream repository explicitly recorded in package mirror path

Fields of work: Development & Engineering
Roles: Backend Developer, Full-Stack Developer, QA / Test Engineer
Specialties: Cross Platform, Testing
Tools: .Net
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 8f7fee318b13f7dd7df272538c011a5860a4489e39e3823856230ef0eef56cf8