find.dart

// Parent with a child & grand child
class ParentWidget extends StatelessWidget {
  
  @override
  Widget build(BuildContext context) {
    return ChildWidget(
      child: GrandChildWidget(),
    );
  }
}

// Tests
void main() {
  testWidgets('parent, child & grand-child hierarchy', (WidgetTester tester) async {
    Widget parentWidget = ParentWidget();
    await tester.pumpWidget(parentWidget);
    
    final childFinder = find.descendant(of: find.byWidget(parentWidget), matching: find.byType(ChildWidget));
    expect(childFinder, findsOneWidget);
    
    final grandChildFinder = find.descendant(of: find.byWidget(parentWidget), matching: find.byType(GrandChildWidget));
    expect(grandChildFinder, findsOneWidget);
    
    final parentFinder = find.ancestor(of: find.byWidget(childWidget), matching: find.byType(ParentWidget));
    expect(parentFinder, findsOneWidget);
  });
}