Problem: you have a method that logs a message using the Microsoft Patterns & Practices Enterprise Library Logging Block, and you would like to write an automated unit test for it in NUnit (or Team System — solution is easily adapted). Logging to a flat file doesn’t work; the file is still open when you try to read it to verify that the message has been logged. Logging to the database doesn’t work; it seems the log isn’t written to the database immediately. And so forth. Is there an in-memory way of reading the logged message?
Solution: I wanted to create a Mock or Spy TraceListener, but didn’t have the time to
work on this. Thus I gave up on it for a while. Then I remembered that the Enterprise Library
downloaded included unit tests of the library itself. Surely Microsoft already solved the
problem for me? Indeed, they have already created a
Setting up your test
- Build the test NUnit testing project.
- In your project, add a reference to the newly-compiled Microsoft.Practices.EnterpriseLibrary.Logging.Tests.dll, and add a proper using statement in your test class.
- In the TestFixtureSetup and TestFixtureTearDown, call `MockTraceListener.Reset()` to clear the log.
- Exercise your system under test
- Check to make sure there is an entry in the MockTraceListener: `Assert.IsNotNull(MockTraceListener.LastEntry, "No log entry has been created");`
- Check the contents of the `MockTraceListener.LastEntry.Message` to see if the specified message has actually been logged
Setting up the config file
As with any other TraceListener, you must specify this MockTracelistener in the NUnit project’s config file:
<add name="sharedMockListener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.Tests.MockTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging.Tests" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Tests.TraceListeners.MockTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging.Tests" />
<allEvents switchValue="All" name="All Events"> <listeners> <add name="sharedMockListener" /> </listeners> </allEvents>
Posted with : Tech, Microsoft .NET Framework, Software Testing