anchor.diff:        var entry = path.join(dir, name);
         return defer(() {
           if (!entryExists(entry)) {
  -          throw new ExpectException('Entry $entry not found.');
  +          throw new TestFailure('Entry $entry not found.');
           }
           return validate(entry);
         });
  
positive.code:           failures.addAll(result.stderr.map((line) => '| $line'));
          }
  
          throw new ExpectException(failures.join('\n'));
        }
  
        return null;
  
negative.code:     return listDir(dir).then((files) {
        var matches = files.where((file) => endsWithPattern(file, name)).toList();
        if (matches.isEmpty) {
          throw new TestFailure('No files in $dir match pattern $name.');
        }
        if (matches.length == 1) return validate(matches[0]);
  
  