anchor.diff:        final Match parts = errorPattern.matchAsPrefix(error);
         if (parts != null) {
           final String message = parts[2];
  -        final File file = File(path.join(_tempDir.path, parts[3]));
  +        final File file = File(path.join(_tempDirectory.path, parts[3]));
           final List<String> fileContents = file.readAsLinesSync();
           final bool isSnippet = path.basename(file.path).startsWith('snippet.');
           final bool isSample = path.basename(file.path).startsWith('sample.');
  
positive.code:       );
      } else {
        return Process.runSync(
          path.canonicalize(Platform.executable),
          <String>[path.canonicalize(_snippetsSnapshotPath)]..addAll(args),
          workingDirectory: workingDirectory,
        );
      }
    }
  
    /// Writes out the given [snippet] to an output file in the [_tempDir] and
    /// returns the output file.
    File _writeSnippet(Snippet snippet) {
      // Generate the snippet.
      final String snippetId = _createNameFromSource('snippet', snippet.start.filename, snippet.start.line);
      final String inputName = '$snippetId.input';
      // Now we have a filename like 'lib.src.material.foo_widget.123.dart' for each snippet.
      final File inputFile = File(path.join(_tempDir.path, inputName))..createSync(recursive: true);
      inputFile.writeAsStringSync(snippet.input.join('\n'));
      final File outputFile = File(path.join(_tempDir.path, '$snippetId.dart'));
      final List<String> args = <String>[
        '--output=${outputFile.absolute.path}',
        '--input=${inputFile.absolute.path}',
  
negative.code:   /// A RegExp that matches a Dart constructor.
    static final RegExp _constructorRegExp = RegExp(r'[A-Z][a-zA-Z0-9<>.]*\(');
  
    /// Whether or not to keep the temp directory around after running.
    ///
    /// Defaults to false.
    final bool _keepTmp;
  
    /// The temporary directory where all output is written. This will be deleted
    /// automatically if there are no errors.
    Directory _tempDirectory;
  
    /// The package directory for the flutter package within the flutter root dir.
    final Directory _flutterPackage;
  