code: def test_warn_on_empty_leaderboard():
      ds = import_dataset()
      aml = H2OAutoML(
          project_name="test_empty_leaderboard",
          include_algos=[],
          seed=1234,
      )
      aml.train(y=ds.target, training_frame=ds.train)
      assert aml.leaderboard.nrow == 0
      warnings = aml.event_log[
          aml.event_log["level"] == "WARN", "message"
      ]
      last_warning = warnings[warnings.nrow - 1, :].flatten()
      assert "Empty leaderboard" in last_warning
  
file_path: h2o-3/h2o-py/tests/testdir_algos/automl/leaderboard/pyunit_automl_leaderboard.py
imports: import os
  import sys
  from h2o.automl import H2OAutoML
  from tests import pyunit_utils
  from _leaderboard_utils import all_algos, check_leaderboard
  from _automl_utils import import_dataset, get_partitioned_model_names
label_desc: Use image node_id 1 for calling a global function with example usage: test_warn_on_empty_leaderboard() without return types