code: def test_ch_sd_test(x, m, expected):
      res = CHTest._sd_test(x, m)
      assert np.allclose(res, expected)
  
imports: from pmdarima.arima.seasonality import CHTest, decompose, OCSBTest
  from pmdarima.arima.utils import nsdiffs
  from pmdarima.compat.pytest import pytest_error_str
  from pmdarima.datasets import load_airpassengers, load_ausbeer, load_austres, load_wineind
  import numpy
  from numpy.testing import assert_almost_equal, assert_array_equal
  from sklearn.utils.validation import check_random_state
  import pytest
  from unittest import mock
label_desc: Use image node_id 8 for calling a global function with example usage: test_ch_sd_test(x, m, expected) without return types