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:   }
  
    var results = <Uri, ResolvedUnitResult>{};
    for (var testUri in testUris) {
      var path = resourceProvider.convertPath(testUri.path);
      var result = await driver.getResult(path) as ResolvedUnitResult;
      var errors =
          result.errors.where((e) => e.severity == Severity.error).toList();
      if (errors.isNotEmpty) {
  
negative.code:     Map<String, List<String>>? skipMap}) async {
    MemberAnnotations<IdValue> memberAnnotations =
        testData.expectedMaps[config.marker]!;
  
    final resourceProvider = MemoryResourceProvider();
    final testFiles = <_TestFile>[];
    for (final entry in testData.memorySourceFiles.entries) {
      final uri = _toTestUri(entry.key);
      final path = resourceProvider.convertPath(uri.path);
      final file = resourceProvider.getFile(path);
      testFiles.add(
        _TestFile(uri: uri, file: file),
      );
      file.writeAsStringSync(entry.value);
    }
  
    final sdkRoot = resourceProvider.newFolder(
      resourceProvider.convertPath('/sdk'),
    );
    createMockSdk(
      resourceProvider: resourceProvider,
      root: sdkRoot,
    );
  
    final contextCollection = AnalysisContextCollectionImpl(
      includedPaths: testFiles.map((e) => e.path).toList(),
      resourceProvider: resourceProvider,
      retainDataForTesting: true,
      sdkPath: sdkRoot.path,
    );
    final analysisContext = contextCollection.contexts.single;
    final analysisSession = analysisContext.currentSession;
    final driver = analysisContext.driver;
  
    Map<Uri, Map<Id, ActualData<T>>> actualMaps = <Uri, Map<Id, ActualData<T>>>{};
    Map<Id, ActualData<T>> globalData = <Id, ActualData<T>>{};
  