Resolve ILogger from a logger factory

[adamhewitt627]

I'm thinking of something like this being added to the built-in resolvers.

private sealed class AutoMockerLoggerResolver : IMockResolver
{
    public void Resolve(MockResolutionContext context)
    {
        if (context.Value is not null) return;

        Type type = context.RequestType;

        if (type == typeof(ILogger))
        {
            ILoggerFactory factory = context.AutoMocker.Get<ILoggerFactory>();
            context.Value = factory.CreateLogger(string.Empty);
        }
        else if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(ILogger<>))
        {
            ILoggerFactory factory = context.AutoMocker.Get<ILoggerFactory>();

            context.Value = typeof(AutoMockerLoggerResolver)
                .GetMethod(nameof(CreateLogger), BindingFlags.Static | BindingFlags.NonPublic)
                .MakeGenericMethod(type.GenericTypeArguments[0])
                .Invoke(null, new object[] { factory });
        }
    }

    private static ILogger<T> CreateLogger<T>(ILoggerFactory factory)
        => factory.CreateLogger<T>();
}

[304NotModified]

That would be great! Or make it opt-in like this for example:

  mocker.AddLoggerMocks();

[adamhewitt627]

I have no idea why I suggested this. What would the benefit be to get a logger this way rather than just the mock?

[304NotModified]

Maybe its an issue that the loggermock returns null for the methods (e.g. beginscope) - 》crashes.

Note: Most of the time there is no need to assert the loggermock.

Personally I create a (generic) spy when we need to assert the logger. The ilogger is hard to verify due to the extensions and conversions.

[MelGrubb]

Well, I wish this wasn't closed. It's the closest thing I've found to what I'm trying to do. I want to NOT mock ILogger. I want to call Mocker.Use and register the open generic logger type with a lambda so that it uses an existing LoggerFactory to create a real logger to be injected during my tests at runtime. Why? So that I can see what happened during the test. I want to call CreateInstance to get my system under test, and I'd like it to use a real Logger. I just want a callback/lambda to specify it so that I can resolve the generic at runtime.

[bamajap]

Well, I wish this wasn't closed. It's the closest thing I've found to what I'm trying to do. I want to NOT mock ILogger. I want to call Mocker.Use and register the open generic logger type with a lambda so that it uses an existing LoggerFactory to create a real logger to be injected during my tests at runtime. Why? So that I can see what happened during the test. I want to call CreateInstance to get my system under test, and I'd like it to use a real Logger. I just want a callback/lambda to specify it so that I can resolve the generic at runtime.

I think I understand what you're describing b/c I do something similar by setting up a console logger for my unit tests. This may work for your use-case.

using Microsoft.Extensions.Logging;
...

var mocker = new AutoMocker(MockBehavior.Strict);
var loggerFactory = LoggerFactory.Create(builder => builder.AddConsole());
var logger = loggerFactory.CreateLogger<ClassUnderTest>();
mocker.Use(logger);

var sut = mocker.CreateInstance<ClassUnderTest>();
...