anchor.diff:    return (result.stdout as String).contains('application/x-mach-binary');
   }
   
  -List<String> findBinaryPaths() {
  +/// Find every binary file in the given [rootDirectory]
  +List<String> findBinaryPaths([String rootDirectory]) {
  +  rootDirectory ??= cacheDirectory;
     final ProcessResult result = Process.runSync(
       'find',
       <String>[
  -      cacheDirectory,
  +      rootDirectory,
         '-type',
         'f',
         '-perm',
  
positive.code: import 'dart:io';
  import 'package:path/path.dart' as path;
  
  String get cacheDirectory {
    final String flutterRepoRoot = path.normalize(path.join(path.dirname(Platform.script.path), '..', '..'));
    return path.normalize(path.join(flutterRepoRoot, 'bin', 'cache'));
  }
  
  bool isBinary(String filePath) {
    final ProcessResult result = Process.runSync(
      'file',
  
negative.code:   return allFiles.where(isBinary).toList();
  }
  
  /// Given the path to a stamp file, read the contents.
  ///
  /// Will throw if the file doesn't exist.
  String readStamp(String filePath) {
    final File file = File(filePath);
    if (!file.existsSync()) {
      throw 'Error! Stamp file $filePath does not exist!';
    }
    return file.readAsStringSync().trim();
  }
  
  /// Return whether or not the flutter cache is up to date.
  bool checkCacheIsCurrent() {
    try {
      final String dartSdkStamp = readStamp(path.join(cacheDirectory, 'engine-dart-sdk.stamp'));
      final String engineVersion = readStamp(path.join(repoRoot, 'bin', 'internal', 'engine.version'));
      return dartSdkStamp == engineVersion;
    } catch (e) {
      print(e);
      return false;
    }
  }
  
  void main() {
    final List<String> failures = <String>[];
  
    if (!Platform.isMacOS) {
      print('Error! Expected operating system "macos", actual operating system '
        'is: "${Platform.operatingSystem}"');
      exit(1);
    }
  
    if (!checkCacheIsCurrent()) {
      print(
        'Warning! Your cache is either not present or not matching your flutter\n'
        'version. Run a `flutter` command to update your cache, and re-try this\n'
        'test.');
      exit(1);
    }
  
    for (final String binaryPath in findBinaryPaths(cacheDirectory)) {
      print('Verifying the code signature of $binaryPath');
      final ProcessResult result = Process.runSync(
        'codesign',
  