code: def test_empty_example_case_on_tree_digraph_raises_error(input_type):
      X, y = make_synthetic_regression()
      if input_type == "dataframe":
          if not PANDAS_INSTALLED:
              pytest.skip(reason="pandas is not installed")
          X = pd_DataFrame(X)
      ds = lgb.Dataset(X, y)
      bst = lgb.train({"num_leaves": 3}, ds, num_boost_round=1)
      example_case = X[:0]
      if input_type == "dataframe":
          example_case = pd_DataFrame(example_case)
      with pytest.raises(
          ValueError, match="example_case must have a single row."
      ):
          lgb.create_tree_digraph(
              bst, tree_index=0, example_case=example_case
          )
  
imports: import numpy
  import pandas
  import pytest
  from sklearn.model_selection import train_test_split
  import lightgbm
  from lightgbm.compat import GRAPHVIZ_INSTALLED, MATPLOTLIB_INSTALLED, PANDAS_INSTALLED, pd_DataFrame
  from .utils import load_breast_cancer, make_synthetic_regression
label_desc: Use image node_id 13 for calling a global function with example usage: test_empty_example_case_on_tree_digraph_raises_error(input_type) without return types