Fhnw.Ecnf.RoutePlanner.RoutePlannerLib.Routes.FindCities C# (CSharp) Method

        public City[] FindCities(TransportModes tmode)
        {
            IEnumerable<City> l = ((from r in routes
                                    where r.TransportMode == tmode
                                    select r.FromCity).Union(
                                   from r in routes
                                   where r.TransportMode == tmode
                                   select r.ToCity)).Distinct();

            return l.ToArray();

        }

        public void TestFindCitiesByTransportMode()
        {
            Cities cities = new Cities();
            cities.ReadCities(@"citiesTestDataLab3.txt");
            var routes = new Routes(cities);
            routes.ReadRoutes(@"linksTestDataLab3.txt");

            City[] citiesByMode = routes.FindCities(TransportMode.Rail);
            Assert.AreEqual(11, citiesByMode.Length);

            City[] emptyCitiesByMode = routes.FindCities(TransportMode.Bus);
            Assert.AreEqual(0, emptyCitiesByMode.Length);
        }