language: node_js
install:
  - npm install koa
  - npm install
node_js:
  - "4"
  - "6"
  - "8"

language: node_js
install:
  - npm install koa
  - npm install
node_js:
  - "8"

Test only on node 8 (need async/await)
Test only on node 8 (need async/await)
