How to detect Mock location in Flutter using Geolocator Plugin

I am trying to detect Mock Location. I have installed Fake location app and enabled Mock Locations in Settings (Under Developer Options). But when I try to detect Mock location using Geolocator, it doesn't work at all.

Future<Position> _determinePosition() async {
bool serviceEnabled;
LocationPermission permission;

serviceEnabled = await Geolocator.isLocationServiceEnabled();
if (!serviceEnabled) {
  return Future.error('Location services are disabled.');
}

permission = await Geolocator.checkPermission();
if (permission == LocationPermission.deniedForever) {
  return Future.error(
      'Location permissions are permanently denied, we cannot request permissions.');
}

if (permission == LocationPermission.denied) {
  permission = await Geolocator.requestPermission();
  if (permission != LocationPermission.whileInUse &&
      permission != LocationPermission.always) {
    return Future.error(
        'Location permissions are denied (actual value: $permission).');
  }
}
return await Geolocator.getCurrentPosition(
    desiredAccuracy: LocationAccuracy.high);
}

And then I call this function as:

_determinePosition().then((position) {
  if (position.isMocked) {
    //.. Show error message
    return;
  }

And this if block is never reached and there is no error log either.