simple unit tests for angular service

Perhaps this is a simple question, but I am new in unit testing and angular, what is the correct approach for write tests for services, that return/set/modify data.

angular.module('myApp').service('optionsService', function(){
    var options = {};

    var getOptions = function(){
        return options;
    },

    var setOptions = function(options){
        options = options;
    }

    return: {
       getOptions: getOptions,
       setOptions: setOptions
    }
})

describe('optionsService', function(){
    var optionsService;

    beforeEach(module('myApp'));
    beforeEach(injector(function(_optionsService_){
       optionsService= _optionsService_;
    }))

    it('should exist', function(){
        expect(optionsService).toBeDefined();
    })

    it('getOptions should return object', function(){
       // help
    })

    it('setOptions should set new options', function(){
       // help
    })
})

Do you know good resources for deep dive for learning unit testing with jasmine. Thanks everyone!