anchor.diff:  # for capybara-webkit
   RUN apt-get install -y libqt4-webkit libqt4-dev xvfb
   
  -# for a JS runtime
  -RUN apt-get install -y nodejs
  -
  -# build phantomjs
  -RUN git clone https://github.com/ariya/phantomjs.git /tmp/phantomjs && \
  -  cd /tmp/phantomjs && git checkout $PHANTOM_JS_TAG && \
  -  ./build.sh --confirm --jobs 2 && mv bin/phantomjs /usr/local/bin && \
  -  rm -rf /tmp/phantomjs
  +# phantomjs
  +RUN npm install -g phantomjs-prebuilt
   
   ENV APP_HOME /myapp
   RUN mkdir $APP_HOME
  
positive.code: FROM ruby:2.3.0-slim
  
  ENV PHANTOM_JS_TAG 2.0.0
  
  RUN apt-get update -qq && apt-get upgrade -y && apt-get install -y \
      git \
      build-essential \
      g++ \
      flex \
  
negative.code:     gperf \
      perl \
      libsqlite3-dev \
      libmysqlclient-dev \
      mysql-client \
      libfontconfig1 \
      libfontconfig1-dev \
      libicu-dev \
      libfreetype6 \
      libfreetype6-dev \
      libssl-dev \
      libxft-dev \
      libpng-dev \
      libjpeg-dev
  
  # for image manipulation
  RUN apt-get install -y imagemagick
  