Angular scope in jasmine controller tests

Trying to understand how do jasmine tests work. I've got a module and a controller:

var app = angular.module('planApp', []);

app.controller('PlanCtrl', function($scope, plansStorage){
var plans = $scope.plans = plansStorage.get();

$scope.formHidden = true;

$scope.togglePlanForm = function() {
    this.formHidden = !this.formHidden;
};

$scope.newPlan = {title: '', description: ''}   ;

$scope.$watch('plans', function() {
    plansStorage.put(plans);
}, true);

$scope.addPlan = function() {
    var newPlan = {
        title: $scope.newPlan.title.trim(),
        description: $scope.newPlan.description
    };

    if (!newPlan.title.length || !newPlan.description.length) {
        return;
    }

    plans.push({
        title: newPlan.title,
        description: newPlan.description
    });

    $scope.newPlan = {title: '', description: ''};
    $scope.formHidden = true;

};

});

plansStorage.get() is a method of a service that gets a json string from localstorage and returns an object.

When I run this test:

var storedPlans = [
  {
    title: 'Good plan',
    description: 'Do something right'
  },
  {
    title: 'Bad plan',
    description: 'Do something wrong'
  }
];

describe('plan controller', function () {
  var ctrl,
  scope,
  service;


  beforeEach(angular.mock.module('planApp'));
  beforeEach(angular.mock.inject(function($rootScope, $controller, plansStorage) {

    scope = $rootScope.$new();
    service = plansStorage;

    spyOn(plansStorage, 'get').andReturn(storedPlans);


    ctrl = $controller('PlanCtrl', {
      $scope: scope,
      plansStorage: service
    });

    spyOn(scope, 'addPlan')

  }));

  it('should get 2 stored plans', function(){
    expect(scope.plans).toBeUndefined;
    expect(service.get).toHaveBeenCalled();
    expect(scope.plans).toEqual([
  {
    title: 'Good plan',
    description: 'Do something right'
  },
  {
    title: 'Bad plan',
    description: 'Do something wrong'
  }
    ]);
  });

  it('should add a plan', function() {
    scope.newPlan = {title: 'new', description: 'plan'};
    expect(scope.newPlan).toEqual({title: 'new', description: 'plan'});
    scope.addPlan();

    expect(scope.addPlan).toHaveBeenCalled();

    expect(scope.plans.length).toEqual(3);
  });

});

first test passes ok, but second one fails. The length of the scope.plans expected to be 3, but it is 2. scope.plans didn't change after scope.addPlan() call.

If I understand that right, the $scope inside addPlan method is not the same as scope that I trying to test in second test.

The question is why? And how do I test the addPlan method?