Unit testing Enterprise Library "Logger" Facade - unit-testing

Question

I'm writing an adapter for Enterprise Library Logging and as per our coding standards, need a way to unit test.
The interface and implementation is simple, but I need a way to check to see that Logger.Write has been called with certain parameters on the log entry. Unfortunately the Logger.Writer does not have a setter, and I don't have any tools to mock a static class.
I'd like to be able to, for example, assert the event ID or the severity for the underlying writer when an adapter method is called.

Answer 1

You can implement a custom tracelistener, and use it as your unit test trace listener:
[ConfigurationElementType(typeof(CustomTraceListenerData))]
public class StubTraceListener : CustomTraceListener
{
private readonly static List<LogEntry> logEntries_ =
new List<LogEntry>();
private readonly static List<string> logMessages_ =
new List<string>();
public override void Write(string message)
{
StubTraceListener.logMessages_.Add(message);
}
public override void WriteLine(string message)
{
StubTraceListener.logMessages_.Add(message);
}
public override void TraceData(TraceEventCache eventCache,
string source, TraceEventType eventType, int id,
object data)
{
LogEntry le = data as LogEntry;
if (le != null)
{
StubTraceListener.logEntries_.Add(le);
if (this.Formatter != null)
{
this.Write(this.Formatter.Format(le));
return;
}
}
base.TraceData(eventCache, source, eventType, id, data);
}
internal static IList<string> GetLogMessages()
{
return new ReadOnlyCollection<string>
(StubTraceListener.logMessages_);
}
internal static IList<LogEntry> GetLogEntries()
{
return new ReadOnlyCollection<LogEntry>
(StubTraceListener.logEntries_);
}
internal static void Reset()
{
StubTraceListener.logEntries_.Clear();
StubTraceListener.logMessages_.Clear();
}
}
Then, in the test project's App.config file include the trace listener like this:
<listeners>
<add listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.CustomTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0,Culture=neutral"
type="Path.To.Your.Project.Folder.StubTraceListener, Your.Test.Project.Name" name="MockTraceListener" />
</listeners>
Then you can easily create the writer as you normally do:
Logger.SetLogWriter(new LogWriterFactory().Create(), false);