Angular "watcher" singletone in CoffeeScript

app.ctrl.coffee

app.controller 'AppCtrl', ['DataLoggingWatcher', (DataLoggingWatcher) ->
  #...
]  

DataLoggingWatcher.coffee

class DataLoggingWatcher

  constructor: (@$rootScope) ->
    @$rootScope.$on 'newData', () => @logToConsole()

  logToConsole: () =>
    console.log 'new data arrived'

angular.module('myApp')

.factory('DataLoggingWatcher', ['$rootScope', ($rootScope) ->
      new DataLoggingWatcher($rootScope)
  ])

DataLoggingWatcher.spec.coffee

describe 'myApp.DataLoggingWatcher', ->
  loggingWatcher = {}
  rootScope = {}

  beforeEach inject( (_$rootScope_)->
    rootScope = _$rootScope_
  )
  
  beforeEach ->
    loggingWatcher = new DataLoggingWatcher(rootScope)

  describe 'constructor', ->
    it 'should log on "newData" event', ->
      spyOn(loggingWatcher,'logToConsole')
      rootScope.$broadcast 'newData'
      expect(loggingWatcher.logToConsole).toHaveBeenCalled()