code: def test_automatically_select_variables(df_vartypes):
      # test case 1: automatically select variables
      transformer = YeoJohnsonTransformer(variables=None)
      X = transformer.fit_transform(df_vartypes)
  
      # expected result
      transf_df = df_vartypes.copy()
      transf_df["Age"] = [10.167, 10.5406, 9.78774, 9.40229]
      transf_df["Marks"] = [0.804449, 0.722367, 0.638807, 0.553652]
  
      # test init params
      assert transformer.variables is None
      # test fit attr
      assert transformer.variables_ == ["Age", "Marks"]
      assert transformer.n_features_in_ == 5
      # test transform output
      pd.testing.assert_frame_equal(X, transf_df)
  
file_path: feature_engine/tests/test_transformation/test_yeojohnson_transformer.py
imports: import pandas
  import pytest
  from sklearn.exceptions import NotFittedError
  from feature_engine.transformation import YeoJohnsonTransformer
label_desc: Use image node_id 1 for calling a global function with example usage: test_automatically_select_variables(df_vartypes) without return types