anchor.diff:  /// Populates [_barbackVersions].
   Map<Version, String> _findBarbackVersions() {
     var versions = {};
  -  var currentBarback = path.join(repoRoot, 'pkg', 'barback');
  +  var currentBarback = p.join(repoRoot, 'pkg', 'barback');
     versions[new Pubspec.load(currentBarback, new SourceRegistry()).version] =
         currentBarback;
   
  -  for (var dir in listDir(path.join(repoRoot, 'third_party', 'pkg'))) {
  -    var basename = path.basename(dir);
  +  for (var dir in listDir(p.join(repoRoot, 'third_party', 'pkg'))) {
  +    var basename = p.basename(dir);
       if (!basename.startsWith('barback')) continue;
       versions[new Version.parse(split1(basename, '-').last)] = dir;
     }
  
positive.code:   if (!_compiledAsync) {
      var result = Process.runSync(dartBin, [
        '--package-root=$_packageRoot/',
        path.join(testDirectory, '..', 'bin', 'async_compile.dart'),
        buildDir,
        '--silent'
      ]);
  
negative.code:   // If the executable looks like a path, get its full path. That way we
    // can still find it when we spawn it with a different working directory.
    if (dartBin.contains(Platform.pathSeparator)) {
      dartBin = p.absolute(dartBin);
    }
  
    // Find the main pub entrypoint.
    var pubPath = _getPubPath(dartBin);
    // TODO(rnystrom): Replace the above line with the following when #104 is
    // fixed.
    //var pubPath = p.join(testDirectory, '..', 'bin', 'pub.dart');
  
    var dartArgs = ['--package-root=$_packageRoot/', '--checked', pubPath,
        '--verbose'];
  