code: def test_wrong_feature_type_error():
      df = pd.DataFrame({"y": [1], "x": [2]})
      with pytest.raises(TypeError) as type_error:
          DFtoVW(df=df, label=SimpleLabel("y"), features="x")
      expected = "Argument 'features' should be a Feature or a list of Feature."
      assert expected == str(type_error.value)
  
imports: import pytest
  import pandas
  from vowpalwabbit.dftovw import ContextualbanditLabel, DFtoVW, Feature, MulticlassLabel, MultiLabel, Namespace, SimpleLabel
label_desc: Use image node_id 19 for calling a global function with example usage: test_wrong_feature_type_error() without return types