anchor.diff:          doxygen python-pydot python-pydot-ng \
           wget \
           xvfb \
  -        rubygems && \
  +        rubygems git && \
       apt-get clean && \
       rm -rf /var/lib/apt/lists/* && \
       gem install coveralls-lcov
  
positive.code: FROM ubuntu:18.04
  
  # Updating packages' repo & installing only the needed packages:
  #   - GL & X11 as needed graphical dependencies
  
negative.code: #   - Doxygen & Dot to generate the documentation
  #   - Wget to download the FBX SDK
  #   - Xvfb to launch a headless server (allows GL context initialisation without a screen)
  #   - Rubygems to get the 'gem' command, used to download coveralls-lcov, and git to fetch info needed by coveralls-lcov
  # Cleaning the apt lists & removing lists' cache entries to save image space
  #   - See: https://docs.docker.com/develop/develop-images/dockerfile_best-practices/#run
  # Downloading coveralls-lcov to upload coverage to Coveralls
  