Question

I’ve previously used log4net, but my current employer uses Enterprise Library application blocks. I had previously developed unit tests for my core logging classes as follows and was wondering if someone knew the equivalent for the OneTimeSetup code below for the logging app block (sorry for the long code post):

public abstract class DataGathererBase
{
  public readonly log4net.ILog logger = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
  public void CollectData()
  {
    this.LogDebug("Initialize started");
  }

  public static class Logger
  {
    private static LoggingSettings settings = LoggingSettings.GetLoggingSettings(new SystemConfigurationSource());

    static Logger()
    {
      log4net.Config.XmlConfigurator.Configure();
    }

    public static void LogDebug(this DataGathererBase current, string message)
    {
      if (current.logger.IsDebugEnabled)
      {
        current.logger.Debug(string.Format("{0} logged: {1}", current.GetType().Name, message));
      }
    }
  }

[TestFixture]
public class LoggerTests:DataGathererBase
{
  private ListAppender appender;
  private static ILog log;

  [TestFixtureSetUp]
  public void OneTimeSetup()
  {
    appender = new ListAppender();
    appender.Layout = new log4net.Layout.SimpleLayout();
    appender.Threshold = log4net.Core.Level.Fatal;
    log4net.Config.BasicConfigurator.Configure(appender);
    log = LogManager.GetLogger(typeof(ListAppender));
  }

  [Test]
  public void TestLogging()
  {
    this.LogDebug("Debug");
    Assert.AreEqual(0, ListAppender.logTable.Count());
  }
}

Answer 1

To give credit, this answer is based on a David Hayden article which is based on an Alois Kraus article, Programatic Configuraton – Enterprise Library (v2.0) Logging Block . Read those two articles for a good look at programmatic access to Enterprise Library logging.

I wasn’t familiar with ListAppender so I created a CustomTraceListener that sticks the log messages in a List<string>:

  public class ListAppender : Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.CustomTraceListener
  {
    private List<string> list = new List<string>();

    public override void Write(string message)
    {
    }

    public override void WriteLine(string message)
    {
      list.Add(message);
    }

    public List<string> LogTable
    {
      get
      {
        return list;
      }
    }
  }

Here is a modified LoggerTests class that programmatically accesses the EL logging classes to setup the tests (this does not use NUnit):

  public class LoggerTests 
  {
    private ListAppender appender;
    private static LogWriter log;

    public void OneTimeSetup()
    {
      appender = new ListAppender();

      // Log all source levels
      LogSource mainLogSource = new LogSource("MainLogSource", SourceLevels.All);
      mainLogSource.Listeners.Add(appender);
    
      // All messages with a category of "Error" should be distributed
      // to all TraceListeners in mainLogSource.
      IDictionary<string, LogSource> traceSources = new Dictionary<string, LogSource>();
      traceSources.Add("Error", mainLogSource);

      LogSource nonExistentLogSource = null;    
      log = new LogWriter(new ILogFilter[0], traceSources, nonExistentLogSource,
                        nonExistentLogSource, mainLogSource, "Error", false, false);
    }

    public void TestLogging()
    {
      LogEntry le = new LogEntry() { Message = "Test", Severity = TraceEventType.Information };
      le.Categories.Add("Debug");
      log.Write(le);

      // we are not setup to log debug messages
      System.Diagnostics.Debug.Assert(appender.LogTable.Count == 0);

      le.Categories.Add("Error");
      log.Write(le);
      
      // we should have logged an error
      System.Diagnostics.Debug.Assert(appender.LogTable.Count == 1);
    }
  }