code: def test_admin_invalid_header(client: TestClient):
      response = client.post("/admin/", headers={"X-Token": "invalid"})
      assert response.status_code == 400, response.text
      assert response.json() == {"detail": "X-Token header invalid"}
  
imports: import pytest
  from dirty_equals import IsDict
  from fastapi.testclient import TestClient
  from fastapi.utils import match_pydantic_error_url
  from ...utils import needs_py39
label_desc: Use image node_id 25 for calling a global function with example usage: test_admin_invalid_header(client) without return types