code: def test_glibc_version_string_confstr_missing(monkeypatch):
      monkeypatch.delattr(os, "confstr", raising=False)
      assert _glibc_version_string_confstr() is None
  
imports: import os
  import pathlib
  import platform
  import sys
  import types
  import warnings
  import pretend
  import pytest
  from packaging import _manylinux
  from packaging._manylinux import _get_glibc_version, _glibc_version_string, _glibc_version_string_confstr, _glibc_version_string_ctypes, _is_compatible, _parse_elf, _parse_glibc_version
label_desc: Use image node_id 11 for calling a global function with example usage: test_glibc_version_string_confstr_missing(monkeypatch) without return types