Unit Test & Log4net - asp.net

Question

I have unit test testing an action in my controller, the action writes to log4net.
When I run my action it works well - writes to log4net .
However , When I run the unit test - the action doesn't write to log4net but doesn't throw any exception.
Does anyone have a solution?

Answer 1

// ARRANGE
var memoryAppender = new MemoryAppender();
BasicConfigurator.Configure(memoryAppender);
// ACT
_sut.DoWhatever();
// ASSERT - using xunit - change the expression to fit your purposes
Assert.True(memoryAppender.GetEvents().Any(le => le.Level == Level.Warn), "Expected warning messages in the logs");
You don't need to add in another layer of indirection by using a logging interface (if you don't want to). I have used the abstracted way for years, but now am moving towards just using the MemoryAppender as it is testing what is actually happening. Just be sure to .Clear() the appender after each test.

Answer 2

Log4net does not throw exceptions: http://logging.apache.org/log4net/release/faq.html
Writing to an log on disk or in a database in a unit test is counterproductive; the whole point is automation. You shouldn't have to check the logs every time you run tests.
If you truly need to verify that a call was made to log something, you should mock the ILog interface and assert that the appropriate method was called.
If you are using a mocking framework, this is trivial. If you aren't, you can create a TestLogger class that implements or partially implements ILog and exposes extra properties that show how many times a given method was called. Your assertions will check that the methods were called as expected.
Here is an example of a class to be tested:
public class MyComponent
{
private readonly ILog _log;
public MyComponent(ILog log)
{
_log = log;
}
public string DoSomething(int arg)
{
_log.InfoFormat("Argument was [{0}]", arg);
return arg.ToString();
}
}
and the test (using Rhino.Mocks to mock the ILog):
[TestClass]
public class MyComponentTests
{
[TestMethod]
public void DoSomethingTest()
{
var logger = MockRepository.GenerateStub<ILog>();
var component = new MyComponent(logger);
var result = component.DoSomething(8);
Assert.AreEqual("8", result);
logger.AssertWasCalled(l => l.InfoFormat(Arg<string>.Is.Anything, Arg<int>.Is.Equal(8)));
}
}

Answer 3

Try adding:
[assembly: log4net.Config.XmlConfigurator()]
To the AssemblyInfo.cs (or init log4net any other way).
Or try using AssemblyInitialize as suggested in this answer.

Answer 4

It is your log4net configuration. Right now it might be in your web.config or log4net.config file in the web/bin. You have to place it in a common location and make it discoverable by both web app and test. Or you have to put it into your unittest.project=>app.config file. But if you have many test projects, it would be duplicated in number of places. So the ideal would be to put it in a common place.

Answer 5

Here's another possible solution if none of the other solutions work for you...
Try writing your log file to the root of the c drive. By default, I set log4net to write to the current directory which is always the directory the unit test is running from right?... wrong! I'm running windows 8 with vs 2012 using MS Unit Test, and it writes the file to a local temp directory which gets deleted after the unit test completes. In my setup it writes the file to here:
C:\Users\[myself]\AppData\Local\Temp\TestResults
Bottom line, any unit tests I write for now on, are going to use a full absolute log file path and not a relative one.