code: def test_propensity(self, n_strata=2):
      stra_eval_method = PropensityStratifiedEvaluation(
          data=self.ml_100k,
          n_strata=n_strata,
          rating_threshold=4.0,
          verbose=True,
      )
      props = np.array(list(stra_eval_method.props.values()))
      self.assertTrue(np.all(props > 0))
  
file_path: cornac/tests/cornac/eval_methods/test_propensity_stratified_evaluation.py
imports: import unittest
  import numpy
  import cornac
  from cornac.data import Reader
  from cornac.eval_methods import PropensityStratifiedEvaluation
  from cornac.models import MF
  from cornac.metrics import MAE, AUC
label_desc: Use image node_id 3 for calling the TestPropensityStratifiedEvaluation obj's underlying member method code with example usage: obj.test_propensity(n_strata) without return types