lmxopcua/tests/Client/ZB.MOM.WW.OtOpcUa.Client.CLI.Tests/LoggerLifecycleTests.cs

using Serilog;
using Serilog.Core;
using Serilog.Events;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Client.CLI.Commands;
using ZB.MOM.WW.OtOpcUa.Client.CLI.Tests.Fakes;

namespace ZB.MOM.WW.OtOpcUa.Client.CLI.Tests;

/// <summary>
/// Regression test for Client.CLI-007: ConfigureLogging must dispose the previously assigned
/// Log.Logger before replacing it, so repeated CLI invocations do not leak sinks.
/// </summary>
public class LoggerLifecycleTests
{
    /// <summary>Verifies that ConfigureLogging disposes previous logger before reassigning.</summary>
    [Fact]
    public async Task ConfigureLogging_DisposesPreviousLogger_BeforeReassigning()
    {
        // Install a tracker logger before the command runs.
        var trackerSink = new DisposeTrackingSink();
        var trackerLogger = new LoggerConfiguration()
            .WriteTo.Sink(trackerSink)
            .CreateLogger();
        Log.Logger = trackerLogger;

        try
        {
            var fakeService = new FakeOpcUaClientService();
            var factory = new FakeOpcUaClientServiceFactory(fakeService);
            var command = new ConnectCommand(factory)
            {
                Url = "opc.tcp://localhost:4840"
            };

            using var console = TestConsoleHelper.CreateConsole();
            await command.ExecuteAsync(console);

            // The command's ConfigureLogging should have disposed the tracker logger we installed.
            trackerSink.Disposed.ShouldBeTrue(
                "Previous Log.Logger should be disposed via Log.CloseAndFlush() before ConfigureLogging assigns a new one.");
        }
        finally
        {
            Log.CloseAndFlush();
        }
    }

    private sealed class DisposeTrackingSink : ILogEventSink, IDisposable
    {
        /// <summary>Gets a value indicating whether the sink has been disposed.</summary>
        public bool Disposed { get; private set; }
        /// <summary>Emits a log event.</summary>
        /// <param name="logEvent">The log event to emit.</param>
        public void Emit(LogEvent logEvent) { }
        /// <summary>Disposes the sink and marks it as disposed.</summary>
        public void Dispose() => Disposed = true;
    }
}