Meziantou.Extensions.Logging.Xunit.v3 3.0.4

Meziantou.Extensions.Logging.Xunit.v3

Statically create XUnitLogger or XUnitLogger<T>

ILogger logger = XUnitLogger.CreateLogger();
ILogger<MyType> logger = XUnitLogger.CreateLogger<MyType>();

These overloads do not take an ITestOutputHelper. The logger resolves TestContext.Current.TestOutputHelper each time it writes, so it always targets the test that is currently running. This is the recommended way to log from code whose lifetime is not tied to a single test, such as a host or a fixture shared by several tests.

Statically create XUnitLogger or XUnitLogger<T> by passing an existing ITestOutputHelper

ILogger logger = XUnitLogger.CreateLogger(testOutputHelper);
ILogger<MyType> logger = XUnitLogger.CreateLogger<MyType>(testOutputHelper);

A logger created this way writes to that specific helper. If the helper belongs to a test that has already finished, the log record is dropped instead of throwing.

Configure the output

Every entry point accepts an optional XUnitLoggerOptions:

ILogger logger = XUnitLogger.CreateLogger(testOutputHelper, new XUnitLoggerOptions
{
    IncludeLogLevel = true,
    IncludeCategory = true,
    IncludeScopes = true,
    TimestampFormat = "HH:mm:ss.fff",
    UseUtcTimestamp = true,
});

// 12:20:41.812 warn [MyNamespace.MyType] Something happened
//  => TheScope

Register the logger with dependency injection

var host = new HostBuilder()
    .ConfigureLogging(builder =>
    {
        builder.AddXunit();
    })
    .Build();

AddXunit has four overloads: no argument, an ITestOutputHelper, an XUnitLoggerOptions, or both. Use the parameterless one to write to whichever test is running, and pass an ITestOutputHelper only when you need to target a specific one.

Because ITestOutputHelper and XUnitLoggerOptions are both optional reference types, AddXunit(null) is ambiguous and does not compile. Call AddXunit() to say "no test output helper", or name the argument (AddXunit(testOutputHelper: null)) if you are passing one through. The same applies to the XUnitLoggerProvider constructors.

Using WebApplicationFactory

If you are using a WebApplicationFactory:

public class UnitTest1(ITestOutputHelper testOutputHelper)
{
    [Fact]
    public async Task Test1()
    {
        using var factory = new WebApplicationFactory<Program>()
            .WithWebHostBuilder(builder =>
            {
                builder.ConfigureLogging(builder =>
                {
                    // You can override the logging configuration if needed
                    //builder.SetMinimumLevel(LogLevel.Trace);
                    //builder.AddFilter(_ => true);

                    // Register the xUnit logger provider
                    builder.AddXunit(testOutputHelper, new XUnitLoggerOptions { IncludeScopes = true });
                });
            });
    }
}

If the factory outlives the test that created it, prefer builder.AddXunit() without the helper so each record goes to the test that is running when it is written.

Blog post about this package: How to write logs from ILogger to xUnit.net ITestOutputHelper