code: def test_variables_trainable_state_follows_layer(self):
      layer = signal_conv.SignalConv2D(1, 1, use_bias=True)
      layer.trainable = False
      layer.build((None, None, None, 1))
      self.assertLen(layer.weights, 3)
      self.assertEmpty(layer.trainable_weights)
  
imports: import os
  from absl.testing import parameterized
  import numpy
  import scipy.signal
  import tensorflow
  from tensorflow_compression.python.layers import initializers
  from tensorflow_compression.python.layers import parameters
  from tensorflow_compression.python.layers import signal_conv
label_desc: Use image node_id 5 for calling the SignalConvTest obj's underlying member method code with example usage: obj.test_variables_trainable_state_follows_layer() without return types