code: def test_plugin_backend():
      mock_entry_point = mock.MagicMock(spec=entrypoints.EntryPoint)
      with mock.patch(
          "entrypoints.get_single", return_value=mock_entry_point
      ) as mock_get_single:
          loader.load_backend("my_plugin")
          # Check calls to entrypoints
          mock_get_single.assert_called_with(
              loader.ENTRYPOINT_GROUP_NAME, "my_plugin"
          )
          # Check backend has been built
          mock_entry_point.load.assert_called_once()
  
imports: from unittest import mock
  import entrypoints
  from mlflow.projects.backend import loader
label_desc: Use image node_id 1 for calling a global function with example usage: test_plugin_backend() without return types