How to mock the Yes/No decision for ngDialogue with Jasmine Karma

I am very new to unit testing. I have one angular service which uses ngDialouge - this is has 2 radio buttons Yes/No.

 angular.module('jasminKarmaPoc1App')
        .factory('fateLayingService', fateLayingService);

 .....

 var response = {}
   response.AvoidPayment = function (playerDetails){

    ....    

    var prom = ngDialog.open(
                        {
                            template: 'scripts/decisionbox/fate-decision-  modal-window.html',
                            controller: 'DecisionBoxController'
                        }
                );
                prom.closePromise.then(function (res) {
                    if (res.value === "1")
                    {
                      //***Below is the one I want to test -i.e. alert and updation of scope ****
                      //alert the message and update some related scope variables login 
                    }
                    if (res.value === "2")
                    {
//**Below is the one I want to test -i.e. alert and updation of scope
                      //alert the message and update some related scope variables login 
                    }

  .....
  return response()

Now I want to unit test messages and test whether scope.msg got updated depending on the dialogue box selection (Yes gives different msg and No gives different msg). If I want to test those messages I need to mock ngDialog and also their choices (Yes/No), but I am confused between how to do it exactly. Any help would be appreciated.