anchor.diff:  
   import 'src/utilities/mock_packages.dart';
   
  -/// Finds an [Element] with the given [name].
  -Element? findChildElement(Element root, String name, [ElementKind? kind]) {
  -  Element? result;
  -  root.accept(_ElementVisitorFunctionWrapper((Element element) {
  -    if (element.name != name) {
  -      return;
  -    }
  -    if (kind != null && element.kind != kind) {
  -      return;
  -    }
  -    result = element;
  -  }));
  -  return result;
  -}
  -
  -/// A function to be called for every [Element].
  -typedef _ElementVisitorFunction = void Function(Element element);
  -
   class AbstractContextTest with ResourceProviderMixin {
     static bool _lintRulesAreRegistered = false;
   
  
positive.code:     verifyCreatedCollection();
    }
  }
  
  /// Wraps the given [_ElementVisitorFunction] into an instance of
  /// [engine.GeneralizingElementVisitor].
  class _ElementVisitorFunctionWrapper extends GeneralizingElementVisitor<void> {
    final _ElementVisitorFunction function;
    _ElementVisitorFunctionWrapper(this.function);
  
    @override
    void visitElement(Element element) {
      function(element);
      super.visitElement(element);
    }
  }
  
negative.code: import 'package:analyzer/dart/analysis/analysis_context.dart';
  import 'package:analyzer/dart/analysis/results.dart';
  import 'package:analyzer/dart/analysis/session.dart';
  import 'package:analyzer/file_system/file_system.dart';
  import 'package:analyzer/src/dart/analysis/analysis_context_collection.dart';
  import 'package:analyzer/src/dart/analysis/byte_store.dart';
  