docstr: A test that the op runs when shape and rank are unknown.
docstr_tok: ["A","test","that","the","op","runs","when","shape","and","rank","are","unknown","."]
code: def test_unknown_shape(self):
      """A test that the op runs when shape and rank are unknown."""
      if context.executing_eagerly():
          return
      signal = array_ops.placeholder_with_default(
          random_ops.random_normal((2, 3, 5)),
          tensor_shape.TensorShape(None),
      )
      self.assertIsNone(signal.shape.ndims)
      self.evaluate(mfcc_ops.mfccs_from_log_mel_spectrograms(signal))
  
file_path: tensorflow/tensorflow/python/kernel_tests/signal/mfcc_ops_test.py
imports: from absl.testing import parameterized
  from tensorflow.python.eager import context
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import random_ops
  from tensorflow.python.ops.signal import mfcc_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 3 for calling the MFCCTest obj's underlying member method code with example usage: obj.test_unknown_shape() without return types