code: def test_probe_operating_system_darwin(self, mock):
      mock.platform = "darwin"
      self.assertEqual(probe_operating_system(), "darwin")
  
imports: import unittest
  from unittest.mock import MagicMock, mock_open, patch
  from artifact_repository import *
label_desc: Use image node_id 9 for calling the TestArtifactRepositoryTool obj's underlying member method code with example usage: obj.test_probe_operating_system_darwin(mock) without return types