С которого можно быстро начать тестирования какого-либо виджета.
import 'package:flutter/material.dart'; void main() => runApp(MaterialApp( debugShowCheckedModeBanner: false, home: MainScreen() )); class MainScreen extends StatefulWidget { @override State createState() => MainScreenState(); }//MainScreen class MainScreenState extends State<MainScreen> { @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(title: Text('MainScreen appBar')), body: Center(child: Text('Body Text')) ); }//build }//MainScreenState