Angular JS Nested Services Unit Testing

I spent all afternoon trying to write a Unit Test for a service that is working as expected, without success. The problem comes from the dependencies injected, because I have another service that is passing the unit tests (it doesn't have dependencies).

The service is this

import angular from 'angular';

export class IPMAService {
  /*@ngInject*/
  constructor($http, localStorageService, appConfig, locationStorageKey) {
    debugger;
    this.$http = $http;
    this.localStorage = localStorageService;
    this.appConfig = appConfig;
    this.locationStorageKey = locationStorageKey;
    if (Object.keys(this.localStorage.get(locationStorageKey)).length < 1) {
      console.log("IPMAService - Initialization (locations not present in local storage)");
      this._getLocationsFromService();
    }
  }

  getLocations() {
    console.log("IPMAService - Get Locations");   
    var locations = this.localStorage.get(this.locationStorageKey);
    if(!locations){
      return this._getLocationsFromService();
    }
    return locations;
  };

  _getLocationsFromService(){
      var _self = this;
      this.$http({
        method: 'GET',
        url: this.appConfig.ipmaWebServices.locations
      }).then((response) => {
        _self.localStorage.set(_self.locationStorageKey, response.data);
        console.log("IPMAService - Saved locations.json to local storage with key: " + _self.locationStorageKey);
        return response;
      })
      .catch((response) => {
        console.log("IPMAService - Erro no acesso à api do IPMA: " + _self.appConfig.ipmaWebServices.locations);
      })
  }
}

export default angular.module('services.ipmaService', [])
  .service('ipmaService', IPMAService)
  .name;

I read a lot about Unit Tests and I can't seem to get it to work. This was my last attempt (not even a basic .toBeDefined(), given that it crashes in the inject function: "TypeError: Cannot convert undefined or null to object"):

'use strict';

import serviceModule from './IPMAService.service';
import LocalStorageModule from 'angular-local-storage';
import constantsModule from '../../app/app.constants';

describe('Service: IPMAService', function () {
    beforeEach(angular.mock.module(serviceModule));
    beforeEach(angular.mock.module(LocalStorageModule));
    beforeEach(angular.mock.module(constantsModule));

    var localStorageService2, service, httpBackend, ipmawebservices, locationStoreKey2;

    beforeEach(inject(function (ipmaService, _$http_, localStorageService, appConfig, locationStoreKey) {
        service = ipmaService;
        httpBackend = _$http_;
        localStorageService2 = localStorageService;
        ipmawebservices = appConfig;
        locationStoreKey2 = locationStorageKey;

    }));

    it ('should be loaded', function() {
        expect(service).toBeDefined();
    });
});

Also...after I get this basic test to pass/work, I would like to know how can I, for example, test the getLocations method since it depends on the _getLocationsFromService method and localStorage (I think I have to use jasmine's SpyOn, but a little help would be great).

Thanks in advance