Can I create a RunData object that works in my test cases?

Hi!
I am developing a turbine application and I want to run automated test cases
through JUnit. However, some methods that I want to test require a RunData
object to store the user in. I can create a DefaultTurbineRunData object and
pass it to the method but an exception is thrown since it doesn't contain a
valid session object, and one of the methods calls
data.removeUserFromSession()
Is there any way to go around this error (and perhaps some similar errors I
haven't come across yes) and create some kind of RunData object that would
work in my test cases?
/Ludwig