Need an example that depicts unit testing a method that has Navigator.push statement

Help Testing & Debugging
1

I need an example of a method being unit tested which contains the Navigator.push method. For ex.
Method to test-:

Future<int> navigateToSecondRoute(BuildContext context){
answer = await Navigator.push(
      context,
      MaterialPageRoute<int>(
        builder: (context) => const SecondRoute(),
      ),
    ).then((onValue) {
      return onValue;
    });
return answer;
}