code: def testAssertsPositiveDf(self):
      df = tf.Variable([1.0, 2.0, -3.0])
      with self.assertRaisesOpError("Argument `df` must be positive."):
          d = chi.Chi(df, validate_args=True)
          self.evaluate([v.initializer for v in d.variables])
          self.evaluate(d.entropy())
  
imports: import numpy
  from scipy import special
  from scipy import stats
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import chi
  from tensorflow_probability.python.distributions import kullback_leibler
  from tensorflow_probability.python.internal import test_util
label_desc: Use image node_id 10 for calling the ChiTest obj's underlying member method code with example usage: obj.testAssertsPositiveDf() without return types