old_contents: import numpy as np
  from numpy.testing import assert_allclose
  import pytest
  import sfs
  
  cart_sph_data = [
      ((1, 1, 1), (np.pi/4, np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((-1, 1, 1), (np.arctan2(1, -1), np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((1, -1, 1), (-np.pi/4, np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((-1, -1, 1), (np.arctan2(-1, -1), np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((1, 1, -1), (np.pi/4, np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
      ((-1, 1, -1), (np.arctan2(1, -1), np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
      ((1, -1, -1), (-np.pi/4, np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
      ((-1, -1, -1), (np.arctan2(-1, -1), np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
  ]
  
  
  @pytest.mark.parametrize('coord, polar', cart_sph_data)
  def testcart2sph(coord, polar):
      x, y, z = coord
      a = sfs.util.cart2sph(x, y, z)
      assert_allclose(a, polar)
  
  
  @pytest.mark.parametrize('coord, polar', cart_sph_data)
  def testsph2cart(coord, polar):
      alpha, beta, r = polar
      b = sfs.util.sph2cart(alpha, beta, r)
      assert_allclose(b, coord)
  
new_contents: import numpy as np
  from numpy.testing import assert_allclose
  import pytest
  import sfs
  
  cart_sph_data = [
      ((1, 1, 1), (np.pi/4, np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((-1, 1, 1), (np.arctan2(1, -1), np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((1, -1, 1), (-np.pi/4, np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((-1, -1, 1), (np.arctan2(-1, -1), np.arccos(1/np.sqrt(3)), np.sqrt(3))),
      ((1, 1, -1), (np.pi/4, np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
      ((-1, 1, -1), (np.arctan2(1, -1), np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
      ((1, -1, -1), (-np.pi/4, np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
      ((-1, -1, -1), (np.arctan2(-1, -1), np.arccos(-1/np.sqrt(3)), np.sqrt(3))),
  ]
  
  
  @pytest.mark.parametrize('coord, polar', cart_sph_data)
  def test_cart2sph(coord, polar):
      x, y, z = coord
      a = sfs.util.cart2sph(x, y, z)
      assert_allclose(a, polar)
  
  
  @pytest.mark.parametrize('coord, polar', cart_sph_data)
  def test_sph2cart(coord, polar):
      alpha, beta, r = polar
      b = sfs.util.sph2cart(alpha, beta, r)
      assert_allclose(b, coord)
  
subject: Use "test_" in test function names