anchor.diff:    TestConfig(this.marker, this.name, {FeatureSet? featureSet})
         : featureSet = featureSet ?? FeatureSet.latestLanguageVersion();
   }
  +
  +class _TestFile {
  +  final Uri uri;
  +  final File file;
  +
  +  _TestFile({
  +    required this.uri,
  +    required this.file,
  +  });
  +
  +  String get path => file.path;
  +}
  
positive.code: import 'package:analyzer/error/error.dart';
  import 'package:analyzer/file_system/file_system.dart';
  import 'package:analyzer/file_system/memory_file_system.dart';
  import 'package:analyzer/src/context/packages.dart';
  import 'package:analyzer/src/dart/analysis/byte_store.dart';
  import 'package:analyzer/src/dart/analysis/driver.dart';
  import 'package:analyzer/src/dart/analysis/performance_logger.dart';
  import 'package:analyzer/src/dart/analysis/testing_data.dart';
  import 'package:analyzer/src/dart/sdk/sdk.dart';
  import 'package:analyzer/src/generated/engine.dart';
  import 'package:analyzer/src/generated/source.dart';
  import 'package:analyzer/src/source/package_map_resolver.dart';
  import 'package:analyzer/src/test_utilities/mock_sdk.dart';
  
  /// Test configuration used for testing the analyzer without experiments.
  
negative.code:   }
  
    var results = <Uri, ResolvedUnitResult>{};
    for (final testFile in testFiles) {
      final testUri = testFile.uri;
      final result = await analysisSession.getResolvedUnit(testFile.path);
      result as ResolvedUnitResult;
      var errors =
          result.errors.where((e) => e.severity == Severity.error).toList();
      if (errors.isNotEmpty) {
  