R8.XunitLogger

Bridges Microsoft.Extensions.Logging with xUnit's ITestOutputHelper so every ILogger call in your application appears in the test runner's output window — with no boilerplate.

Supports xUnit v2 (net6.0 / netstandard2.1) and xUnit v3 (net8.0 / net10.0).

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Installation

dotnet add package R8.XunitLogger

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Options

Option	Type	Default	Description
MinimumLevel	LogLevel	Information	Global minimum log level. Acts as the fallback when no SetMinimumLevel override or IConfiguration entry matches.
IncludeTimestamp	bool	true	Prepend [date time] to every log line.
IncludeScopes	bool	false	Render the active logging scope chain (=> outer => inner) before each message.
ServiceProvider	IServiceProvider?	null	When set, log-level filtering is read from IConfiguration (Logging:LogLevel section) instead of the options above. Automatically set to the DI container's IServiceProvider when using AddXunitLogger, but you can override it with any IServiceProvider of your choice — in both unit and integration tests.
SetMinimumLevel(…)	fluent chain	—	Per-namespace level overrides. See Per-namespace levels.
Categories	IList<string>	—	Obsolete. Use SetMinimumLevel instead.

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Usage

Unit tests (AddXunit)

public class UnitTest
{
    private readonly ILoggerFactory _loggerFactory;

    public UnitTest(ITestOutputHelper outputHelper)
    {
        _loggerFactory = new LoggerFactory().AddXunit(outputHelper, options =>
        {
            options.MinimumLevel = LogLevel.Debug;
            options.IncludeScopes = true;
        });
    }

    [Fact]
    public void Test()
    {
        var logger = _loggerFactory.CreateLogger<MyService>();
        // ...
    }
}

Integration tests with DI — per test (AddXunitLogger)

The test class itself implements IXunitLogProvider, so each test gets its own ITestOutputHelper wired directly:

public class IntegrationTest : IXunitLogProvider, IDisposable
{
    private readonly ITestOutputHelper _outputHelper;
    private readonly ServiceProvider _serviceProvider;

    public IntegrationTest(ITestOutputHelper outputHelper)
    {
        _outputHelper = outputHelper;
        _serviceProvider = new ServiceCollection()
            .AddLogging()
            .AddXunitLogger(message => OnWriteLine?.Invoke(message))
            .AddScoped<MyService>()
            .BuildServiceProvider();
        OnWriteLine += _outputHelper.WriteLine;
    }

    public event Action<string> OnWriteLine;

    public void Dispose() => OnWriteLine -= _outputHelper.WriteLine;

    [Fact]
    public void Test()
    {
        var svc = _serviceProvider.GetRequiredService<MyService>();
        // ...
    }
}

Integration tests with DI — shared fixture (IClassFixture)

Use this when the service container is expensive to build and should be shared across all tests in the class. The fixture implements IXunitLogProvider; each test subscribes its own ITestOutputHelper in the constructor and unsubscribes in Dispose:

// Fixture (shared across tests in the same class)
public class MyFixture : IXunitLogProvider
{
    public readonly ServiceProvider Services;

    public MyFixture()
    {
        Services = new ServiceCollection()
            .AddLogging()
            .AddXunitLogger(message => OnWriteLine?.Invoke(message), options =>
            {
                options.MinimumLevel = LogLevel.Warning;
            })
            .AddScoped<MyService>()
            .BuildServiceProvider();
    }

    public event Action<string> OnWriteLine;
}

// Test class
public class MyTests : IClassFixture<MyFixture>, IDisposable
{
    private readonly MyFixture _fixture;
    private readonly ITestOutputHelper _outputHelper;

    public MyTests(MyFixture fixture, ITestOutputHelper outputHelper)
    {
        _fixture = fixture;
        _outputHelper = outputHelper;
        _fixture.OnWriteLine += _outputHelper.WriteLine;
    }

    public void Dispose() => _fixture.OnWriteLine -= _outputHelper.WriteLine;

    [Fact]
    public void Test()
    {
        var svc = _fixture.Services.GetRequiredService<MyService>();
        // ...
    }
}

With appsettings.json / IConfiguration

Register IConfiguration in the DI container before calling AddXunitLogger. AddXunitLogger automatically wires the service provider so Logging:LogLevel entries from your configuration override MinimumLevel and SetMinimumLevel:

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning",
      "MyApp.Services": "Debug"
    }
  }
}

_serviceProvider = new ServiceCollection()
    .AddSingleton<IConfiguration>(new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json")
        .Build())
    .AddLogging()
    .AddXunitLogger(message => OnWriteLine?.Invoke(message))
    .BuildServiceProvider();

Note: When using AddXunitLogger, ServiceProvider is automatically set to the DI container's own IServiceProvider. You can still override it with a custom one if needed.

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Per-namespace log levels

SetMinimumLevel returns a dedicated chain object so you can stack overrides without accidentally accessing other options:

options.MinimumLevel = LogLevel.Warning;   // global default

options
    .SetMinimumLevel("MyApp",         LogLevel.Debug)    // everything in MyApp → Debug
    .SetMinimumLevel("MyApp.Data",    LogLevel.Warning)  // but Data layer → Warning
    .SetMinimumLevel("Microsoft",     LogLevel.None)     // silence Microsoft internals
    .SetMinimumLevel("System",        LogLevel.None);

The longest matching prefix wins. MinimumLevel is used when no prefix matches.

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Scope rendering

Set IncludeScopes = true to render the active scope chain in Microsoft.Extensions.Logging style:

[25/04/2026 13:00:00] warn: MyApp.Services.OrderService[0]
      => Request abc-123 => ProcessOrder
      Insufficient stock for product 42

Supported scope types:

• String: logger.BeginScope("my scope") → => my scope
• Structured: logger.BeginScope("Order {Id}", 42) → => Order 42
• Dictionary: logger.BeginScope(new Dictionary<string,object>{ ["OrderId"] = 42, ["CustomerId"] = "cust-99" }) → => OrderId: 42 => CustomerId: cust-99
• Nested: outer → inner rendered left-to-right

Example:

using (logger.BeginScope(new Dictionary<string, object>
       {
           ["OrderId"] = 42,
           ["CustomerId"] = "cust-99"
       }))
{
    logger.LogInformation("Processing order");
    logger.LogWarning("Stock low for order");
}

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See full examples in the sample project