Consider adding a XUnitLogger<T>

[paulomorgado]

Is your feature request related to a problem?

In unit tests, there are times when I need an ILogger<T> without the overhead of dependency injection, ILoggerFactory, or a LoggerProvider. This can simplify test setup and make the tests more straightforward.

Describe the solution you'd like

I would like to have a XUnitLogger<T> class that implements the ILogger<T> interface. This logger should be easy to instantiate directly in unit tests without requiring dependency injection, ILoggerFactory, or a provider. It should integrate with xUnit's output capturing mechanisms to display log messages in the test results and support various log levels.

Describe alternatives you've considered

I haven't considered any alternatives that would be as simple and lightweight as this.

Simple implementation

    private sealed class XUnitLogger<T> : XUnitLogger, ILogger<T>
    {
        public XUnitLogger(IMessageSink messageSink, XUnitLoggerOptions options) : base(typeof(T).FullName, messageSink, options)
        {
        }

        public XUnitLogger(IMessageSinkAccessor accessor, XUnitLoggerOptions options) : base(typeof(T).FullName, accessor, options)
        {
        }

        public XUnitLogger(ITestOutputHelper outputHelper, XUnitLoggerOptions options) : base(typeof(T).FullName, outputHelper, options)
        {
        }

        public XUnitLogger(ITestOutputHelperAccessor accessor, XUnitLoggerOptions options) : base(typeof(T).FullName, accessor, options)
        {
        }
    }

[martincostello]

What about something like this:

+ public static class XUnitLoggerFactory
+ {
+     public ILogger<T> Create<T>(IMessageSink messageSink, XUnitLoggerOptions? options = null);
+     public ILogger<T> Create<T>(IMessageSinkAccessor accessor, XUnitLoggerOptions? options = null);
+     public ILogger<T> Create<T>(ITestOutputHelper outputHelper, XUnitLoggerOptions? options = null);
+     public ILogger<T> Create<T>(ITestOutputHelperAccessor accessor, XUnitLoggerOptions? options = null);
+ }

Then no internal implementation details need to be exposed, and it's basically the same as NullLoggerFactory:

- var foo = new SystemUnderTest(NullLoggerFactory.Instance.CreateLogger<SystemUnderTest>(TestOutputHelper));
+ var foo = new SystemUnderTest(XUnitLoggerFactory.Create<SystemUnderTest>(TestOutputHelper));

[paulomorgado]

Looks great!

But I would go a bit further, though.

A ILoggerFactory factory (😄) to bind to IMessageSink, IMessageSinkAccessor, ITestOutputHelper, ITestOutputHelperAccessor and then use whatever comes out of Microsoft.Extensions.Logging,

If you would like this one, I can submit a PR.

[martincostello]

I'm not 100% sure what you mean (but can take some guesses) - do you have an API shape in mind?

[paulomorgado]

@martincostello.

I've been fiddling with it, and came up to this:

var loggerFactory = LoggerFactory.Create(builder => builder
        .AddProvider(new XUnitLoggerProvider(outputHelper, xunitLoggerOptions))
        .SetMinimumLevel(LogLevel.Trace));

Given the nobs in XUnit and range of XunitLoggerOptions, I think it's as good as we can get.

I think all that's needed is adding this option to the docs. What do you think?

[martincostello]

Sure - that works for me!

[paulomorgado]

Do you want me to send a PR, or is it easier for you to just doing it?

[martincostello]

PR welcome, but if you'd rather not/too busy, then I'll do it tomorrow.