Found in

• Issue Typos in flutter_test/lib/src/controller.dart #143173
• PR Fix and test SemanticsController.simulatedAccessibilityTraversal #143386

In SemanticsController.simulatedAccessibilityTraversal, the start and end parameters are deprecated. They are replaced by startNode and endNode, but writing a test for this in the context of multiple views fails.

I wrote such a test in packages/flutter_test/test/multi_view_controller_test.dart

testWidgets('simulatedAccessibilityTraversal - startNode and endNode in same view', (WidgetTester tester) async {
    tester.binding.ensureSemantics();
    await pumpViews(tester: tester);
    expect(
      tester.semantics.simulatedAccessibilityTraversal(
        startNode: find.semantics.byValue('View2Child1'),
        endNode: find.semantics.byValue('View2Child3'),
      ).map((SemanticsNode node) => node.label),
      <String>[
        'View2Child1',
        'View2Child2',
        'View2Child3',
      ],
    );
  });

but it failed with

Bad state: No element

When the exception was thrown, this was the stack:
#0      Iterable.single (dart:core/iterable.dart:674:25)
#1      SemanticsController.simulatedAccessibilityTraversal (package:flutter_test/src/controller.dart:207:57)

This is coming from here when we are trying to look up the SemanticsOwner:

The new API works in the single view world, so I am going to move forward with that PR to resolve other issues unrelated to this one.

cc @goderbauer