Do not swallow exception from Audit

Author: sungam3r

src/Serilog.Extensions.Logging/Extensions/Logging/SerilogLogger.cs

@@ -74,18 +74,20 @@ public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Except
             return;
         }
 
+        bool parsed = false;
         try
         {
-            Write(level, eventId, state, exception, formatter);
+            Write(level, eventId, state, exception, formatter, out parsed);
         }
-        catch (Exception ex)
+        catch (Exception ex) when (!parsed)
         {
             SelfLog.WriteLine($"Failed to write event through {typeof(SerilogLogger).Name}: {ex}");
         }
     }
 
-    void Write<TState>(LogEventLevel level, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
+    void Write<TState>(LogEventLevel level, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter, out bool parsed)
     {
+        parsed = false;
         var logger = _logger;
         string? messageTemplate = null;
 
@@ -153,6 +155,7 @@ void Write<TState>(LogEventLevel level, EventId eventId, TState state, Exception
 
         var parsedTemplate = MessageTemplateParser.Parse(messageTemplate ?? "");
         var evt = new LogEvent(DateTimeOffset.Now, level, exception, parsedTemplate, properties);
+        parsed = true;
         logger.Write(evt);
     }
 

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

@@ -7,6 +7,7 @@
 using Serilog.Debugging;
 using Serilog.Extensions.Logging.Tests.Support;
 using Xunit;
+using Serilog.Core;
 
 namespace Serilog.Extensions.Logging.Tests;
 
@@ -469,4 +470,27 @@ public void MismatchedMessageTemplateParameterCountIsHandled()
 
         Assert.Empty(sink.Writes);
     }
+
+    [Fact]
+    public void ExceptionFromAuditSinkIsUnhandled()
+    {
+        var serilogLogger = new LoggerConfiguration()
+            .AuditTo.Sink(new MySink())
+            .CreateLogger();
+
+        var provider = new SerilogLoggerProvider(serilogLogger);
+        var logger = provider.CreateLogger(Name);
+
+        var ex = Assert.Throws<AggregateException>(() => logger.LogInformation("Normal text"));
+        Assert.IsType<NotImplementedException>(ex.InnerException);
+        Assert.Equal("Oops", ex.InnerException.Message);
+    }
+
+    private class MySink : ILogEventSink
+    {
+        public void Emit(LogEvent logEvent)
+        {
+            throw new NotImplementedException("Oops");
+        }
+    }
 }