title: Can I get log output only for failures with boost unit tests
body: <p>I have some logging in my application (it happens to be log4cxx but I am flexible on that), and I have some unit tests using the boost unit test framework.  When my unit tests run, I get lots of log output, from both the passing and failing tests (not just boost assertions logged, but my own application code's debug logging too).  I would like to get the unit test framework to throw away logs during tests that pass, and output logs from tests that fail (I grew to appreciate this behaviour while using python/nose).</p>
  
  <p>Is there some standard way of doing this with the boost unit test framework?  If not, are there some start of test/end of test hooks that I could use to buffer my logs and conditionally output them to implement this behaviour myself?</p>