I am using jasmine for testing my angular controllers.
I am catching errors and success in the .then(successCallback, errorCallback)
Although it is working fine on the bases of live functionality but am confused how to write a spy for returning an error as it is always caught in the successCallback()

Following is the controller :-

angular.module('myApp')

.controller('LoginCtrl', function ($scope, $location, loginService, SessionService) {

    $scope.errorMessage = '';



    $scope.login = function () {



      var credentials = {

          email: this.email,

          password: this.password

      };



     SessionService.resetSession();

     var request = loginService.login(credentials);



     request.then(function(promise){ //successfull callback

        if (promise['status'] === 200){

             //console.log('login');

            $location.path('/afterloginpath');

        }

      },

     function(errors){  //fail call back

      //  console.log(errors);

        $location.path('/login');

     });

    };

});

My test case :-

'use strict';



describe('Controller: LoginCtrl', function () {



  // load the controller's module

  beforeEach(module('myApp'));



  var LoginCtrl, scope, location, login, loginReturn, session;

  var credentials = {'email': '[email protected]', 'password': 'admin123'};



  // Initialize the controller and a mock scope

 beforeEach(inject(function ($controller, $rootScope, $location, _loginService_, _SessionService_) {



    scope = $rootScope.$new();

    LoginCtrl = $controller('LoginCtrl', {

      $scope: scope

    });



    location = $location;

    login = _loginService_;

    session = _SessionService_;

    scope.errorMessage = '';

    spyOn(login, login).andCallFake(

      function(){

        return {

          then: function(response){

            response(loginReturn);

          }

        }

      }

    );



    spyOn(session, setName).andCallFake(function(){

      return true;

    });

  }));



  it('should go to login when login fail', function () {

    loginReturn = function(){

      return{

        successfullyCallback: {throwError:true},

        failCallback: {status: 400, 'data' : {'errors' : [{type:invalid_data,target:email,password}]}}

      }

    };



    var wrong_creds = {email: '[email protected]', password: 'wrong_password'};

    scope.email = wrong_creds.email;

    scope.password = wrong_creds.password;



scope.login();



    expect(location.path()).toBe(/login);

    expect(scope.errorMessage).toBe('username or password combination is invalid');

  });



});