class_docstr: Unit test class for testing scikit-learn converter.
code: def test_conversion_bad_inputs(self):
      # Error on converting an untrained model
      with self.assertRaises(TypeError):
          model = Ridge()
          spec = convert(model, "data", "out")
  
      # Check the expected class during conversion.
      with self.assertRaises(TypeError):
          model = OneHotEncoder()
          spec = convert(model, "data", "out")
  
file_path: coremltools/coremltools/test/sklearn_tests/test_ridge_regression.py
imports: import unittest
  import pandas
  from coremltools._deps import _HAS_SKLEARN
  from coremltools.models.utils import _is_macos, _macos_version, evaluate_regressor
label_desc: Use image node_id 3 for calling the RidgeRegressionScikitTest obj's underlying member method code with example usage: obj.test_conversion_bad_inputs() without return types