selectEmulator function

AdbDevice selectEmulator(List<AdbDevice> devices, { String? requested, })

Picks the emulator to send fixes to, or throws StateError with a message to show the user.

With requested (a serial), that device must be listed, be an emulator and be ready. Without it, exactly one ready emulator must be running: the choice is never guessed when several are open, because other apps on them would receive the mock locations too. Real devices are never chosen (emu geo fix only works on emulators).

Implementation

AdbDevice selectEmulator(List<AdbDevice> devices, {String? requested}) {
  final listed = devices.isEmpty ? 'none' : devices.join(', ');
  if (requested != null) {
    final match = devices.where((d) => d.serial == requested).firstOrNull;
    if (match == null) throw StateError('device $requested not found (adb devices: $listed)');
    if (!match.isEmulator) throw StateError('$requested is not an emulator; "emu geo fix" needs an emulator');
    if (!match.isReady) throw StateError('$requested is ${match.state}');
    return match;
  }
  final emulators = devices.where((d) => d.isEmulator && d.isReady).toList();
  if (emulators.isEmpty) throw StateError('no running emulator found (adb devices: $listed)');
  if (emulators.length > 1) {
    throw StateError(
      'several emulators are running (${emulators.map((d) => d.serial).join(', ')}); choose one with --device',
    );
  }
  return emulators.single;
}