wercker.yaml

build:
  steps:
    - script:
        name: Enable virtual display
        code: |-
          # Start xvfb which gives the context an virtual display
          # which is required for tests that require an GUI
          export DISPLAY=:99.0
          start-stop-daemon --start --quiet --pidfile /tmp/xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 -screen 0 1024x768x24 -ac +extension GLX +render -noreset
          # Give xvfb time to start. 3 seconds is the default for all xvfb-run commands.
          sleep 3