code: def test_unknown_output_transform():
      estimator = lgb.LGBMRanker(n_estimators=1, random_state=1)
      estimator.fit(
          np.array([[1], [2], [3]]),
          np.array([1, 2, 3]),
          group=np.array([3]),
      )
  
      assembler = LightGBMModelAssembler(estimator)
  
      with pytest.raises(
          ValueError,
          match="Unsupported objective function 'lambdarank'",
      ):
          assembler.assemble()
  
file_path: m2cgen/tests/assemblers/test_boosting_lightgbm.py
imports: import lightgbm
  import numpy
  import pytest
  from m2cgen import ast
  from m2cgen.assemblers import LightGBMModelAssembler
  from tests import utils
label_desc: Use image node_id 10 for calling a global function with example usage: test_unknown_output_transform() without return types