private:
  std::string root_dir_;
  static int rng_val_;
  static std::string cloud_path_;
  static std::string tmp_dir_;
};

int ModularFileSystemTest::rng_val_;
std::string ModularFileSystemTest::cloud_path_;
std::string ModularFileSystemTest::tmp_dir_;

// As some of the implementations might be missing, the tests should still pass
// if the returned `Status` signals the unimplemented state.