Example of Navigator 2.0 Pages methods bug

main.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

final parser = RootRouterParser();
final delegate = RootRouterDelegate();

const indexes = ['First', 'Second', 'Third', 'Fourth', 'Fifth'];

int index = 0;
bool overridePages = false;
final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey();

class MyApp extends StatelessWidget {
  const MyApp({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) => MaterialApp.router(
        title: 'Navigator 2.0 Example',
        routeInformationParser: parser,
        routerDelegate: delegate,
      );
}

class RootRouterParser extends RouteInformationParser<dynamic> {
  @override
  Future<dynamic> parseRouteInformation(RouteInformation routeInformation) async => '';
}

class RootRouterDelegate extends RouterDelegate<dynamic> with ChangeNotifier, PopNavigatorRouterDelegateMixin<dynamic> {
  RootRouterDelegate() : navigatorKey = GlobalKey();

  @override
  final GlobalKey<NavigatorState> navigatorKey;
  List<Page> _pages = [
    buildMaterialPage<void>(EmptyPage(id: 'First', index: index)),
  ];

  @override
  Widget build(BuildContext context) => Navigator(
        key: navigatorKey,
        pages: _pages,
        onPopPage: _onPopPage,
      );

  void addPage() {
    index++;
    final String id = index >= indexes.length ? '${index + 1}' : indexes[index];
    if (overridePages) {
      _pages = [..._pages, buildMaterialPage<void>(EmptyPage(id: id, index: index))];
      print('Add new page with overrides');
      scaffoldKey.currentState.showSnackBar(const SnackBar(content: Text('Add new page with overrides')));
    } else {
      _pages.add(buildMaterialPage<void>(EmptyPage(id: id, index: index)));
      print('Add new page without overrides');
      scaffoldKey.currentState.showSnackBar(const SnackBar(content: Text('Add new page without overrides')));
    }
    notifyListeners();
  }

  bool _onPopPage(Route<dynamic> route, dynamic data) => true;

  @override
  Future<void> setNewRoutePath(dynamic configuration) async {}
}

class EmptyPage extends StatelessWidget {
  const EmptyPage({
    @required this.id,
    @required this.index,
    Key key,
  }) : super(key: key);

  final String id;
  final int index;

  @override
  Widget build(BuildContext context) => Scaffold(
        key: index == 0 ? scaffoldKey : ValueKey(id),
        appBar: AppBar(title: Text('Title - $id')),
        body: Center(child: Text('Empty page - $id')),
        floatingActionButton: FloatingActionButton(
          onPressed: delegate.addPage,
          tooltip: 'Add page',
          child: const Icon(Icons.add),
        ),
      );
}

Page buildMaterialPage<T>(
  Widget child, {
  String name,
  Object arguments,
}) =>
    MaterialPage<T>(
      child: child,
      name: name,
      arguments: arguments,
    );