While I am working on hero animation in flutter, I want to write a test for it which tests that when we tap on an image in a message list page the navigation takes place to lightbox page and the image animates smoothly. I am finding a difficulty in tracking the image during the hero animation. Below is the code for the same that I have implemented:

Setup code:

late PerAccountStore store;
late FakeApiConnection connection;

final channel = eg.stream();
final message = eg.streamMessage(stream: channel,
  contentMarkdown: ContentExample.imageSingle.html, topic: 'test topic');

Future<void> setupMessageListPage(WidgetTester tester) async {
  addTearDown(testBinding.reset);
  final subscription = eg.subscription(channel);
  await testBinding.globalStore.add(eg.selfAccount, eg.initialSnapshot(
    streams: [channel], subscriptions: [subscription]));
  store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
  connection = store.connection as FakeApiConnection;
  await store.addUser(eg.selfUser);

  connection.prepare(json:
    eg.newestGetMessagesResult(foundOldest: true, messages: [message]).toJson());

  await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
    child: MessageListPage(initNarrow: const CombinedFeedNarrow())));

  await tester.pumpAndSettle();
}

Test code:

testWidgets('hero animation occurs when opening lightbox from message list', (tester) async {
  prepareBoringImageHttpClient();
  await setupMessageListPage(tester);

  // Find the initial message image
  final messageContentFinder = find.byWidgetPredicate((widget) =>
    widget is MessageContent && widget.message.id == message.id
  );
  expect(messageContentFinder, findsOneWidget);

  final imageFinder = find.descendant(
    of: messageContentFinder,
    matching: find.byType(RealmContentNetworkImage)
  );
  expect(imageFinder, findsOneWidget);

  // Find the Hero and get its initial position via RenderObject
  final heroFinder = find.ancestor(
    of: imageFinder,
    matching: find.byType(Hero)
  );
  expect(heroFinder, findsOneWidget);
  final initialElement = tester.element(heroFinder);
  final initialRenderBox = initialElement.renderObject as RenderBox;
  final initialPosition = initialRenderBox.localToGlobal(Offset.zero);

  // Get the Hero's tag - this will be consistent throughout the animation
  final heroTag = tester.widget<Hero>(heroFinder).tag;

  // Start the animation
  await tester.tap(imageFinder);
  await tester.pump(); // Build the new page

  // Wait a bit to let the animation start
  await tester.pump(const Duration(milliseconds: 50));

  // Find the destination Hero Element by looking in the lightbox route
  final heroElement = tester.elementList(find.byType(Hero))
    .where((element) => (element.widget as Hero).tag == heroTag)
    .where((element) =>
      element.findAncestorWidgetOfExactType<InteractiveViewer>() != null)
    .single;
  final heroRenderBox = heroElement.renderObject as RenderBox;

  // Pump incremental frames during the 300ms animation
  final animationDuration = const Duration(milliseconds: 250); // Remaining time
  final steps = 5; // Check 5 points during animation

  for (int i = 1; i <= steps; i++) {
    await tester.pump(animationDuration ~/ steps);

    // Look up the hero by its element identity
    final currentElement = tester.element(
      find.byElementPredicate((element) => element == heroElement));
    expect(currentElement, same(heroElement)); // Element should stay the same

    // Get current position via RenderObject
    final currentPosition = heroRenderBox.localToGlobal(Offset.zero);
    print('Step $i position: $currentPosition (initial: $initialPosition)');

    // By this point in the animation, the position should definitely be changing
    check(currentPosition).anyOf([
      (it) => it.dy.not((it) => it.equals(initialPosition.dy)),
      (it) => it.dx.not((it) => it.equals(initialPosition.dx))
    ]);
  }

  await tester.pumpAndSettle();
  debugNetworkImageHttpClientProvider = null;
});

I am getting the logs as:

LightboxHero hero animation occurs when opening lightbox from message list                                                                    
Step 1 position: Offset(0.0, 0.0) (initial: Offset(37.0, 385.0))
Step 2 position: Offset(0.0, 0.0) (initial: Offset(37.0, 385.0))
Step 3 position: Offset(0.0, 0.0) (initial: Offset(37.0, 385.0))
Step 4 position: Offset(0.0, 0.0) (initial: Offset(37.0, 385.0))
Step 5 position: Offset(0.0, 0.0) (initial: Offset(37.0, 385.0))

Why at each time frame I am getting same current position and I think it is the final position after the hero animation is completed. But I want to track the image during the hero animation. How can I do the same?