How can I access these field in testing ( Flutter)?

**I have these fields below in state class and I want to test if these fields work correctly. So I write testing dart file, how can I access these field in testing file **

class _LoginPageState extends State<LoginPage> {
      String _phoneNumber = "";
  String _smsCode = "";
  String _verificationId = "";
  int _currentStep = 0;

  List<StepState> _stepsState = [
    StepState.editing,
    StepState.indexed,
    StepState.indexed
  ];

  bool _showProgress = false;
  String _displayName = '';
  File _imageFile;

  bool _labeling = false;

  List<ImageLabel> _labels = List();

}