How to capture log4net output in xunit2

I've read http://ift.tt/1FXFrbU and it seems to apply to making my test output specific message during the test running but I would really like to be able to capture the log4net output that is already integrated into the classes I am testing.

In the past i have set up log4net to use a TraceLogger and the test framework was able to associate the output with the test. (different testing framework). How can I somehow associate log4net output to the Xunit IOutputHelper?