var defaults = {
  hide: false,
  delay: 1500,
  css: {
    color: 'blue'
  }
}
var settings = extend(true, defaults,{
  delay: 1700,
  css: {
    border: '1px solid red'
  }
})
expect(settings).to.eql({
  hide: false,
  delay: 1700,
  css: {
    color: 'blue',
    border: '1px solid red'
  }
})