def get_file_path_for_wpt_test(self, test_name):
        """Returns the real file path for the given WPT test.

        Or None if the test is not a WPT.
        """
        match = self.WPT_REGEX.match(test_name)
        if not match:
            return None
        wpt_path = match.group(1)
        path_in_wpt = match.group(2)
        file_path_in_wpt = self.wpt_manifest(wpt_path).file_path_for_test_url(
            path_in_wpt)
        if not file_path_in_wpt:
            return None
        return self._filesystem.join(wpt_path, file_path_in_wpt)