message: Use yarn for packages installation
diff: @@ -3,16 +3,24 @@ sudo: false
  language: node_js
  node_js:
  - "6"
  +
  +cache:
  + yarn: true
  + directories:
  + - node_modules
  os:
  - linux
  +
  before_install:
  # Use a virtual display.
  - export DISPLAY=:99.0
  - sh -e /etc/init.d/xvfb start
  # Install latest chrome.
  - export CHROME_BIN=chromium-browser
  +
  install:
  - - npm install
  + - yarn install
  +
  script:
  - npm run lint
  - npm run test
  