flutter_flutter/packages/flutter_tools/templates/create/lib/main.dart.tmpl

import 'package:flutter/material.dart';
{{#withDriverTest}}
import 'package:flutter_driver/driver_extension.dart';
{{/withDriverTest}}

void main() {
{{#withDriverTest}}
  // Starts the app with Flutter Driver extension enabled to allow Flutter Driver
  // to test the app.
  enableFlutterDriverExtension();
{{/withDriverTest}}
  runApp(
    new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new FlutterDemo(),
    ),
  );
}

class FlutterDemo extends StatefulWidget {
  FlutterDemo({Key key}) : super(key: key);

  @override
  _FlutterDemoState createState() => new _FlutterDemoState();
}

class _FlutterDemoState extends State<FlutterDemo> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Flutter Demo'),
      ),
      body: new Center(
        child: new Text(
            'Button tapped $_counter time${ _counter == 1 ? '' : 's' }.'),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ),
    );
  }
}