class_docstr: Test _UpFIRDn object
code: def __init__(self, up, down, h, x_dtype):
      self.up = up
      self.down = down
      self.h = np.atleast_1d(h)
      self.x_dtype = x_dtype
      self.rng = np.random.RandomState(17)
  
imports: import numpy
  from itertools import product
  from numpy.testing import assert_equal, assert_allclose
  from pytest import raises
  import pytest
  from scipy.signal import upfirdn, firwin
  from scipy.signal._upfirdn import _output_len, _upfirdn_modes
  from scipy.signal._upfirdn_apply import _pad_test
label_desc: Use image node_id 1 to create a new UpFIRDnCase object  with example: obj = UpFIRDnCase(up, down, h, x_dtype)