user_riverpod.dart

/// * si usamos Riverpod

void main() => runApp(ProviderScope(child: MyApp()));

...

final userStateNotifierProvider = Provider<UserStateNotifier>(
	(_) => UserStateNotifier();
);

...

class MyWidget extends ConsumerWidget {
  @override
  Widget build(BuildContext context, ScopedReader watch) {

		final userState = watch(userStateNotifierProvider.state);

    return Scaffold(
      body: Center(
        child: Text('${userState.runtimeType}'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          context.read(userStateNotifierProvider).logIn(User());
        },
      ),
    );
  }
}