code: def test_error_if_y_not_passed(df_normal_dist):
      # test case 3: raises error if target is not passed
      with pytest.raises(TypeError):
          encoder = DecisionTreeDiscretiser()
          encoder.fit(df_normal_dist)
  
file_path: feature_engine/tests/test_discretisation/test_decision_tree_discretiser.py
imports: import numpy
  import pandas
  import pytest
  from sklearn.exceptions import NotFittedError
  from feature_engine.discretisation import DecisionTreeDiscretiser, EqualWidthDiscretiser
label_desc: Use image node_id 4 for calling a global function with example usage: test_error_if_y_not_passed(df_normal_dist) without return types