Property in LogEvent should not be overridden by scope

src/Serilog.Extensions.Logging/Extensions/Logging/SerilogLoggerProvider.cs

@@ -105,13 +105,13 @@ public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
 
         scopeCollector.ReverseItems();
 
-        _externalScopeProvider?.ForEachScope(static (state, parameters) =>
+        _externalScopeProvider?.ForEachScopeReversed(static (state, parameters) =>
         {
             SerilogLoggerScope.EnrichWithStateAndCreateScopeItem(
                 parameters.LogEvent,
                 parameters.PropertyFactory,
                 state,
-                update: true,
+                update: false,
                 out var scopeItem);
 
             if (scopeItem != null)
@@ -177,3 +177,30 @@ public void AddItem(LogEventPropertyValue scopeItem)
         }
     }
 }
+
+
+file static class Extensions
+{
+    public static void TryClear<T>(this List<T> list)
+    {
+        if (list.Count > 0)
+            list.Clear();
+    }
+
+    private static readonly ThreadLocal<List<object?>> _list = new(() => []);
+
+    public static void ForEachScopeReversed<TState>(this IExternalScopeProvider provider, Action<object?, TState> callback, TState state)
+    {
+        var list = _list.Value!;
+        list.TryClear();
+
+        provider.ForEachScope((m, _) => list.Add(m), state);
+
+        for (var i = list.Count - 1; i >= 0; i--)
+        {
+            callback(list[i], state);
+        }
+
+        list.TryClear();
+    }
+}

test/Serilog.Extensions.Logging.Tests/SerilogLoggerTests.cs

@@ -634,4 +634,33 @@ public void ConflictingEventIdTemplatePropertyIsIgnored()
         var recordedEventId = Assert.IsType<int>(recordedEventIdPropertyValue.Value);
         Assert.Equal(loggedEventId, recordedEventId);
     }
+
+    [Theory]
+    [InlineData(true)]
+    [InlineData(false)]
+    public void LoggingScopeShouldNotReplacePropertyInLogEvent(bool withExternalScopeProvider)
+    {
+        var sink = new CollectingSink();
+        using var logger = new LoggerConfiguration().WriteTo.Sink(sink).CreateLogger();
+        var serilogLoggerProvider = new SerilogLoggerProvider(logger);
+
+        var services = new ServiceCollection();
+        services.AddLogging(l => l.AddSerilog(logger));
+
+        using var serviceProvider = services.BuildServiceProvider();
+        var msLogger = withExternalScopeProvider
+            ? serviceProvider.GetRequiredService<ILogger<SerilogLoggerTest>>()
+            : serilogLoggerProvider.CreateLogger(Name);
+
+        using (msLogger.BeginScope(new Dictionary<string, object?> { { "Value", 1 } }))
+        using (msLogger.BeginScope(new Dictionary<string, object?> { { "Value", 2 } }))
+        {
+            msLogger.LogInformation("Value: {Value}", 3);
+        }
+
+        var logEvent = sink.Writes.First();
+        var value = (logEvent.Properties["Value"] as ScalarValue)?.Value;
+
+        Assert.Equal(3, value);
+    }
 }