Basic widget testing

basic_widget_test.dart

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'demo',
      home: Scaffold(
        appBar: AppBar(
          title: Text('demo title'),
        ),
        body: Center(
          child: Text('demo content'),
        ),
      ),
    );
  }
}

void main() {
  testWidgets('MyWidget has correct title and message', (WidgetTester tester) async {
    await tester.pumpWidget(MyWidget());
    final titleFinder = find.text('demo title');
    final contentFinder = find.text('demo content');
    expect(titleFinder, findsOneWidget);
    expect(contentFinder, findsOneWidget);
  });
}