Webmeisterei: How to run Plone coredev test locally and quietly

start a framebuffer for display :1 in a separate console

$ Xvfb :1

before running the tests, set the environment variable

$ export DISPLAY=:1
$ bin/alltests

(see https://github.com/collective/robotsuite/issues/5 for another possible solution: using phantomjs as a browser)