jUnit + jMock and log4j

Question

I've given a task to do a JUnit + JMock on a program created by other programmer. Most of the class has this static field logger, i.e.:

static Log logger = LogFactory.getLog(SomeClass.class.getName());

I am creating an instance of SomeClass by instantiating it inside my setUp() method. When I run my jUnit class I am getting this error message:

log4j:ERROR setFile(null,true) call failed.
java.io.FileNotFoundException:  (No such file or directory)

I tried to do the the manual log4j configuration by calling DOMConfigurator.configure("log4j.xml"); inside the setUp() method but I'm still getting the same error message above.

The question is:

• How can I run my unit test + mocking in a class which calls other class that uses LogFactory.getLog
  
• Should I configure log4j inside my setup method so that the mocking and unit test runs without an exception?
  
• How should I do it.

Answer 1

Actually there are two types of problem that I have which I thought to be one, a log4j problem in jUnit. You can actually continue with the jUnit + jMock even if log4j is not configured properly it will throw an exception but won't stop jUnit execution.

The problem that I have are:
1. FileNotFoundException exception with message "setFile(null, true) call failed"
2. jMock unexpected invocation error

I solved number 1 (even though I could still continue unit testing even with log4j exception) by putting a VM argument -Dlog4j.configuration=file:/C:/log4j/log4j.xml. I was getting an exception because it was using the log4j.xml inside the compiled directory (default output folder for compiled java classes). That log4j has this parameter <param name="File" value="${error.file}"/>. So log4j is looking for a log file that has a file name ${error.file} (which doesn't exist). Like what I said above I solved it by putting a VM argument above.

Lesson learned: If you are getting FileNotFoundException in log4j execution try to put -Dlog4j.debug as a VM argument to see where log4j is pulling the config file.

I solve number 2 by completing all the expected object inside the method that I am testing. Though jMock message is kinda ambiguous.

Lesson learned: Unexpected invocation usually means you are missing an objects or mock-objects in your test-method that are being used in the method that you are unit testing. It also means you haven't set an expectations on the object that it is trying to invoke

Answer 2

You have two options...

• Use PowerMock and mock up the static getLog method call.
• Configure a log4j.properties for your test cases

In Maven projects, the second option is easy since you simply need to create a log4j.properties in your test/resources folder.