code: def test_quantile_strategy_empty_train():
      est = DummyRegressor(strategy="quantile", quantile=0.4)
      with pytest.raises(ValueError):
          est.fit([], [])
  
imports: import numpy
  import pytest
  import scipy.sparse
  from sklearn.base import clone
  from sklearn.dummy import DummyClassifier, DummyRegressor
  from sklearn.exceptions import NotFittedError
  from sklearn.utils._testing import assert_almost_equal, assert_array_almost_equal, assert_array_equal, ignore_warnings
  from sklearn.utils.fixes import CSC_CONTAINERS
  from sklearn.utils.stats import _weighted_percentile
label_desc: Use image node_id 23 for calling a global function with example usage: test_quantile_strategy_empty_train() without return types