How to activate logging in plone testing?

In order to test our Zope based application, we use plone.testing.

It works like a charm, but I cannot find out how to get hold on the logfiles.

I installed SiteErrorLog and via pdb and app.error_log I am able to view the logs. But I want the logs from the test run to be written to the hard disk, as it is common for a normal installation.

In our development and also our production setup, the zope.conf defines where the logfiles should be written to. But as far as I know there is no zope.conf for the plone.testing setup.

Any hint is appreciated.