private async Task ExpireLocation(string callsign, bool shouldUpdate)
        {
            if (shouldUpdate)
            {
                var lr = Fixture.Create<LocationRecord>();
                lr.Callsign = callsign;
                lr.Expired = false;
                GoodLocations.Add(lr);
            }

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

            var service = new LocationService(context.Object);

            await service.ExpireLocation(callsign);

            if (shouldUpdate)
            {
                foreach (var gl in GoodLocations.Where(l => l.Callsign == callsign))
                    Assert.True(gl.Expired);

                context.Verify(c => c.SaveChangesAsync());
            }
            else
            {
                context.Verify(c => c.SaveChangesAsync(), Times.Never);
            }
        }