vue npm run unit Error: [vuex] vuex requires a Promise polyfill in this browser.

PhantomJS 2.1.1 (Mac OS X 0.0.0) ERROR

Error: [vuex] vuex requires a Promise polyfill in this browser.

at webpack:///~/vuex/dist/vuex.js:145:0 <- index.js:9871

解決方法：

npm install --save-dev babel-polyfill

karma.conf.js

files: [
  '../node_modules/babel-polyfill/dist/polyfill.js',
  'index.js'
],