code: def test_get_package_names(self, mock_subprocess):
      self.assertSameElements(
          pip_utils.get_package_names(),
          ["absl-py", "aiohttp", "alembic"],
      )
      mock_subprocess.assert_called_once()
  
imports: import subprocess
  from unittest import mock
  import tensorflow
  from tfx.tools.cli import pip_utils
label_desc: Use image node_id 1 for calling the PipUtilsTest obj's underlying member method code with example usage: obj.test_get_package_names(mock_subprocess) without return types