    static ChunkSpec badData() {
      std::string data("\000\000\000\000\0000000", 9);
      std::vector<uint8_t> chunk(data.begin(), data.end());
      ChunkSpec spec;
      spec.valid = true;
      spec.data = chunk;
      return spec;
    }
    static ChunkSpec badData() {
      std::string data("\000\000\000\000\0000000", 9);
      std::vector<uint8_t> chunk(data.begin(), data.end());
      ChunkSpec spec;
      spec.valid = true;
      spec.data = chunk;
      return spec;
    }