How to unit test of a function which are inside another one - angularjs

Question

For unit testing I use jasmine.I want to test the filterList function .
How could I do that ? The problem is I mock the service object, but how to declare the method inside the mock object so that I can test filterList function.
Ignore syntax , because I copy paste the code and delete some lines, so chances are high that there is lots of syntax error.
function (_,angular) {
'use strict';
var ngDependencies = ['StateService','$scope','$rootScope'];
var Constructor = function Constructor(StateService,$scope,$rootScope) {
var self = this;
self.defaultSelectedCompany = {};
self.companies = {
available: []
};
var ChangeListener = StateService.subscribe(function () {
self.companies.available = StateService.getAvailable('clients');
self.myCompanyList = _.map(self.companies.available, function companyList(user) {
return {
id: user.name};
});
self.filterList = function filterList($searchVal, $list) {
return _.filter($list, function (item) {
return item.displayValue.toLowerCase().indexOf($searchVal.toLowerCase()) >= 0 ||
item.secondaryValue.toLowerCase().indexOf($searchVal.toLowerCase()) >= 0;
});
};
self.updateDefaultCompany(self.myCompanyList[0]);
});
self.updateDefaultCompany = function updateDefaultCompanyPreference(selected) {
self.defaultSelectedCompany = selected;
};
$scope.$on('$destroy', ChangeListener);
};
Constructor.$inject = ngDependencies;
return Constructor;
And my spec files is as bellow
function (angular, _) {
'use strict';
var MockStateService = {
name: 'GlobalStateService',
subscribe: jasmine.createSpy('subscribe').and.callFake(function subscribe(state){
return {
filterList : function filterList($searchVal, $list) {
return _.filter($list, function (item) {
return item.displayValue.toLowerCase().indexOf($searchVal.toLowerCase()) >= 0 ||
item.secondaryValue.toLowerCase().indexOf($searchVal.toLowerCase()) >= 0;
});
}
};
})
};
describe('Controller', function () {
beforeEach(function () {
module(Module.name);
utils.useMocks([
MockStateService
]);
});
beforeEach(inject(function ($controller, $rootScope) {
this.scope = $rootScope.$new();
this.reqDrawerCtrl = $controller('SettingsController', {$scope: this.scope});
}));
describe('filterList', function () {
it('is a function', function () {
expect(typeof this.reqDrawerCtrl.filterList).toBe('function');
});
});
});