If you got this error:
kees@zeno:~/Projects/buildout.coredev$ xvfb-run ./bin/test -m Products.CMFPlone
Running Products.CMFPlone.testing.CMFPloneLayer:Functional tests:
Set up plone.testing.zca.LayerCleanup in 0.000 seconds.
Set up plone.testing.z2.Startup in 0.147 seconds.
Set up plone.app.testing.layers.PloneFixture in 5.623 seconds.
Set up plone.app.event.testing.PAEventLayer in 0.562 seconds.
Set up plone.app.contenttypes.testing.PloneAppContenttypes in 1.353 seconds.
Set up Products.CMFPlone.testing.ProductsCMFPloneLayer in 0.078 seconds.