Serilog Not Outputting Anything

Question

Using .Net 4.6 I have a static Serilog helper class - I've stripped down to the essentials as follows:

public static class SerilogHelper
    {
        private static ILogger log;

        private static ILogger CreateLogger()
        {
            if (log == null)
            {
                string levelString = SSOSettingsFileManager.SSOSettingsFileReader.ReadString(
                                    "BizTalk.Common", "serilog.minimum-level");

                SerilogLevel level = (SerilogLevel)Enum.Parse(typeof(SerilogLevel), levelString);

                string conString = SSOSettingsFileManager.SSOSettingsFileReader.ReadString(
                                    "BizTalk.Common", "serilog.connection-string");

                var levelSwitch = new LoggingLevelSwitch();
                levelSwitch.MinimumLevel = (Serilog.Events.LogEventLevel)level;

                log = new LoggerConfiguration()
                    .MinimumLevel.ControlledBy(levelSwitch)
                    .WriteTo.MSSqlServer(connectionString: conString, tableName: "Serilog", autoCreateSqlTable: true)
                    .WriteTo.RollingFile("log-{Date}.txt")
                    .CreateLogger();
            }

            return log;
        }

        public static void WriteString(string content)
        {
            var logger = CreateLogger();
            logger.Information(content);
        }

I have the following unit test:

        [TestMethod]
        public void UN_TestSerilog1()
        {  
            Common.Components.Helpers.SerilogHelper.WriteString("Simple logging");
        }

I've stepped through the debugger to be sure that the "level" variable is being set correctly - it's an enum named "Debug" with value of 1.

Although the Sql Server table is created ok, I don't see any rows inserted or any log txt file. I've also tried calling logger.Error(content) but still no output.

I've used the same helper code previously on a different site / project and it worked ok. Where did I go wrong this time?

Answer 1

Serilog.Sinks.MSSqlServer is a "periodic batching" sink and by default, it waits 5 seconds before sending the logs to the database. If your test ends before the sink had a chance to write the messages to the database, they are simply lost...

You need to make sure you dispose the logger before your test runner ends, to force the sink to flush the logs to the database at that point. See Lifecycle of Loggers.

((IDisposable) logger).Dispose();

Of course, if you are sharing a static log instance across multiple tests, you can't just dispose the logger inside of a single test as that would mean the next test that runs won't have a logger to write to... In that case, you should look at your testing framework support for executing code once, before the test suite run starts, and once again, for when the a test suite run ends.

I'm guessing you are using MSTest (because of the TestMethod), so you probably want to look into AssemblyInitialize and AssemblyCleanup, which would give you the opportunity to initialize the logger for all tests, and clean up after all tests finished running...

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