anchor.diff:  #sudo sh -c 'echo "deb http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list'
   
   RUN apt-get install make
  -ADD Makefile /build/Makefile
  -ADD tox.ini /build/tox.ini
  -ADD pytest.ini /build/pytest.ini
  -ADD setup.py /build/setup.py
  -ADD README.rst /build/README.rst
  -ADD HISTORY.rst /build/HISTORY.rst
  -ADD purkinje /build/purkinje
  +
  +# Build tox environment
  +RUN cd /build; tox -r
  +
   #ENTRYPOINT ["/bin/bash", "-c", "cd", "/build", ";", "make"]
   #ENTRYPOINT "date"
   ENTRYPOINT cd /build ; make test
  
positive.code: RUN apt-get -y update
  RUN apt-get -y upgrade
  # RUN apt-get -y install nodejs google-chrome-stable firefox
  RUN apt-get -y install nodejs firefox  python-pip
  
  RUN npm install
  
  
negative.code: 
  RUN apt-get -y install python-dev
  
  # pro forma; test layer invalidation
  RUN apt-get install htop
  
  ADD Makefile /build/Makefile
  ADD tox.ini /build/tox.ini
  ADD pytest.ini /build/pytest.ini
  ADD setup.py /build/setup.py
  ADD README.rst /build/README.rst
  ADD HISTORY.rst /build/HISTORY.rst
  ADD purkinje /build/purkinje
  
  
  # Python
  RUN pip install --upgrade -r dev-requirements.txt --download-cache $HOME/.pip-cache --use-mirrors
  ENTRYPOINT "/bin/bash"
  RUN echo "Installed Python packages:"
  RUN pip freeze
  
  