travis-ci yarn test

.travis.yml

@@ -8,6 +8,17 @@ node_js:
   - "6"
   - "stable"
   
+before_install:
+  # https://yarnpkg.com/en/docs/install_ci
+  - curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -
+  - sudo apt-key adv --keyserver pgp.mit.edu --recv D101F7899D41F3C3
+  - echo "deb http://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+  - sudo apt-get update -qq
+  - sudo apt-get install -y -qq yarn
+cache:
+  directories:
+  - $HOME/.yarn-cache
+  
 script: "npm run travis"
 
 after_success: