code: func (mock *Mock) Watch(paths []string, onEvent func(event fsnotify.Event), onClose func()) error {
  	go func() {
  		for {
  			select {
  			case event, ok := <-mock.eventChan:
  				if !ok {
  					onClose()
  					return
  				}
  				onEvent(event)
  			}
  		}
  	}()
  	return nil
  }
docs: // Watch calls onEvent when event arrives and onClose when channel is closed