title: ERROR in flutter: widget_test.dart cannot detect MyApp()
body: <p>Being a total beginner I am trying out various flutter feature and I am stuck at running the main.dart due to errors in the widget_test.dart file. 
  Please point out if the error is due to some other reason.</p>
  
  <p><strong>main.dart</strong></p>
  
  <pre><code>import 'package:flutter/material.dart';
   void main(){
     var app = MaterialApp(
       title: 'FlutterApp',
       debugShowCheckedModeBanner: true,
       theme: ThemeData(
          primaryColor: Colors.black12,
          accentColor: Colors.orange,
       ),
       home: Scaffold(
         appBar: AppBar(
           title: Text('Stateless'),
           backgroundColor: Colors.black,
           ),
     ),
     );
     runApp(app);
   }
  </code></pre>
  
  <p><strong>widget_test.dart</strong></p>
  
  <pre><code>// This is a basic Flutter widget test.
  //
  // To perform an interaction with a widget in your test, use the WidgetTester
  // utility that Flutter provides. For example, you can send tap and scroll
  // gestures. You can also use WidgetTester to find child widgets in the widget
  // tree, read text, and verify that the values of widget properties are correct.
  
  import 'package:flutter/material.dart';
  import 'package:flutter_test/flutter_test.dart';
  
  import 'package:stateless/main.dart';
  
  void main() {
    testWidgets('Counter increments smoke test', (WidgetTester tester) async {
      // Build our app and trigger a frame.
      await tester.pumpWidget(MyApp()); //error over here
  
      // Verify that our counter starts at 0.
      expect(find.text('0'), findsOneWidget);
      expect(find.text('1'), findsNothing);
  
      // Tap the '+' icon and trigger a frame.
      await tester.tap(find.byIcon(Icons.add));
      await tester.pump();
  
      // Verify that our counter has incremented.
      expect(find.text('0'), findsNothing);
      expect(find.text('1'), findsOneWidget);
    });
  }
  </code></pre>
  
  <p><em>This is my very first question and I a very sorry if I couldn't place the question in a proper way</em></p>