ASP.Net Core Logging

See docs.asp.net

Nuget packages

"Microsoft.Extensions.Logging"
One or more loggers:
- "Microsoft.Extensions.Logging.Console" - console logging.
- "Microsoft.Extensions.Logging.EventLog" - windows events.
- Another CoreFx-compatible logger (Serilog is one: Serilog.Framework.Logging)

Startup

Startup.Configure: loggerFactory.AddConsole(); or loggerFactory.AddSerilog()
Or configure log filtering eg loggerFactory.AddConsole(LogLevel.Debug) (default is Verbose)
For file logging, take IHostingEnvironment and use the hostEnv.ContentRootPath
You can log in Configure - take argument ILoggerFactory. Use it after AddConsole.

Use

Either- take argument ILoggerFactory and created a named logger

var logger = loggerFactory.CreateLogger("Catchall Endpoint");
//Debug-Verbose (default)-Information-Warning-Error-Critical
logger.LogWarning("Something happened {path}", context.Request.Path);
Or = take argument ILogger<T> where T is probably your classname.

Unit Tests

In a test you will need to provide an ILogger<X>. Provide it with NullLogger<X>.Instance

var validator = new X(NullLogger<X>.Instance);

NLog

Sample NLog setup in .net 6 Program.cs

    public class Program
    {
        public static void Main(string[] args)
        {

            Trace.Listeners.Add(new NLogTraceListener());

            var builder = WebApplication.CreateBuilder(args);

            // NLog: Setup NLog for Dependency injection
            builder.Logging.ClearProviders();
            builder.Host.UseNLog();

            builder.Services.AddControllers();