public async Task GetLocations()
        {
            GoodLocations.Clear();

            GoodLocations.AddRange(new[]
            {
                new LocationRecord
                {
                     Callsign = "WR01",
                     ReadingTime = new DateTimeOffset(2016, 1, 1, 1, 1, 1, TimeSpan.Zero),
                     Latitude = 1,
                     Longitude = 1
                },
                new LocationRecord
                {
                     Callsign = "WR01",
                     ReadingTime = new DateTimeOffset(2016, 1, 1, 1, 2, 1, TimeSpan.Zero),
                     Latitude = 2,
                     Longitude = 2
                },
                new LocationRecord
                {
                     Callsign = "WR02",
                     ReadingTime = new DateTimeOffset(2016, 1, 1, 3, 1, 1, TimeSpan.Zero),
                     Latitude = 3,
                     Longitude = 3
                },
                new LocationRecord
                {
                     Callsign = "WR02",
                     ReadingTime = new DateTimeOffset(2016, 1, 1, 1, 1, 1, TimeSpan.Zero),
                     Latitude = 4,
                     Longitude = 4
                },
                new LocationRecord
                {
                     Callsign = "WR03",
                     ReadingTime = new DateTimeOffset(2016, 1, 1, 1, 1, 1, TimeSpan.Zero),
                     Latitude = 5,
                     Longitude = 5
                }
            });

            var locations = MockHelpers.CreateMockLocationDbSet(GoodLocations);
            var context = CreateMockLocationContext(locations.Object);

            var service = new LocationService(context.Object);

            var res = (await service.GetLocations()).ToList();

            var wr01 = res.Single(l => l.Callsign == "WR01");
            Assert.Equal(2, wr01.Latitude);
            Assert.Equal(2, wr01.Longitude);

            var wr02 = res.Single(l => l.Callsign == "WR02");
            Assert.Equal(3, wr02.Latitude);
            Assert.Equal(3, wr02.Longitude);

            var wr03 = res.Single(l => l.Callsign == "WR03");
            Assert.Equal(5, wr03.Latitude);
            Assert.Equal(5, wr03.Longitude);
        }