code: def test_singleton(self, xp, scp, len_h, len_x):
      # gh-9844: lengths producing expected outputs
      h = xp.zeros(len_h)
      h[len_h // 2] = 1.0  # make h a delta
      x = xp.ones(len_x)
      y = scp.signal.upfirdn(h, x, 1, 1)
      return y
  
file_path: cupy/tests/cupyx_tests/scipy_tests/signal_tests/test_upfirdn.py
imports: from itertools import product
  import pytest
  import numpy
  from cupy import testing
  from cupyx.scipy.signal._upfirdn import _output_len
label_desc: Use image node_id 1 for calling the TestUpfirdn obj's underlying member method code with example usage: obj.test_singleton(xp, scp, len_h, len_x) and returns: y