Chrome API mocking library.
npm install chrome-mock
In most cases you will want to set this as a global at the top of your test file, because chrome is a global in your extension code.
chrome = require('chrome-mock')
To use the I18n library, chrome-mock loads a default messages.json file that has only one string in it, 'test' If you pass a string that does not exist, you will receive a blank string back.
If you want to load a different messages.json file, for example the one you use in your chrome extension then use the method below in your test file.