code: def test_inspect_main_url(capsys):
      """inspect_main interface, with url argument"""
  
      class InventoryHandler(http.server.BaseHTTPRequestHandler):
          def do_GET(self):
              self.send_response(200, "OK")
              self.end_headers()
              self.wfile.write(inventory_v2)
  
          def log_message(*args, **kwargs):
              # Silenced.
              pass
  
      url = "http://localhost:7777/" + INVENTORY_FILENAME
  
      with http_server(InventoryHandler):
          inspect_main([url])
  
      stdout, stderr = capsys.readouterr()
      assert stdout.startswith("c:function\n")
      assert stderr == ""
  
imports: import http.server
  from unittest import mock
  import pytest
  from docutils import nodes
  from sphinx import addnodes
  from sphinx.ext.intersphinx import INVENTORY_FILENAME, _get_safe_url, _strip_basic_auth, fetch_inventory, inspect_main, load_mappings, missing_reference, normalize_intersphinx_mapping
  from sphinx.ext.intersphinx import setup
  from tests.test_util.test_util_inventory import inventory_v2, inventory_v2_not_having_version
  from tests.utils import http_server
label_desc: Use image node_id 19 for calling a global function with example usage: test_inspect_main_url(capsys) without return types