new_contents: from unittest.mock import patch
  
  import pytest
  
  from knowit.utils import detect_os
  
  
  @pytest.mark.parametrize(
      'os_name, sys_platform, expected', [
          ('nt', None, 'windows'),
          ('dos', None, 'windows'),
          ('os2', None, 'windows'),
          ('ce', None, 'windows'),
          (None, 'darwin', 'macos'),
          (None, None, 'unix'),
      ]
  )
  def test_detect_os_is_windows(os_name, sys_platform, expected):
      with patch('knowit.utils.os') as mock_os:
          mock_os.name = os_name
          with patch('knowit.utils.sys') as mock_sys:
              mock_sys.platform = sys_platform
              assert detect_os() == expected
  
subject: Add tests for detect_os