old_contents: from numpy import cos, cosh, sin, sinh
  from numpy.testing import assert_allclose, assert_equal
  
  from poliastro._math.special import stumpff_c2 as c2, stumpff_c3 as c3
  
  
  def test_stumpff_functions_near_zero():
      psi = 0.5
      expected_c2 = (1 - cos(psi**0.5)) / psi
      expected_c3 = (psi**0.5 - sin(psi**0.5)) / psi**1.5
  
      assert_allclose(c2(psi), expected_c2)
      assert_allclose(c3(psi), expected_c3)
  
  
  def test_stumpff_functions_above_zero():
      psi = 3.0
      expected_c2 = (1 - cos(psi**0.5)) / psi
      expected_c3 = (psi**0.5 - sin(psi**0.5)) / psi**1.5
  
      assert_equal(c2(psi), expected_c2)
      assert_equal(c3(psi), expected_c3)
  
  
  def test_stumpff_functions_under_zero():
      psi = -3.0
      expected_c2 = (cosh((-psi) ** 0.5) - 1) / (-psi)
      expected_c3 = (sinh((-psi) ** 0.5) - (-psi) ** 0.5) / (-psi) ** 1.5
  
      assert_equal(c2(psi), expected_c2)
      assert_equal(c3(psi), expected_c3)
  
new_contents: from numpy import cos, cosh, sin, sinh
  from numpy.testing import assert_allclose
  
  from poliastro._math.special import stumpff_c2 as c2, stumpff_c3 as c3
  
  
  def test_stumpff_functions_near_zero():
      psi = 0.5
      expected_c2 = (1 - cos(psi**0.5)) / psi
      expected_c3 = (psi**0.5 - sin(psi**0.5)) / psi**1.5
  
      assert_allclose(c2(psi), expected_c2)
      assert_allclose(c3(psi), expected_c3)
  
  
  def test_stumpff_functions_above_zero():
      psi = 3.0
      expected_c2 = (1 - cos(psi**0.5)) / psi
      expected_c3 = (psi**0.5 - sin(psi**0.5)) / psi**1.5
  
      assert_allclose(c2(psi), expected_c2, rtol=1e-10)
      assert_allclose(c3(psi), expected_c3, rtol=1e-10)
  
  
  def test_stumpff_functions_under_zero():
      psi = -3.0
      expected_c2 = (cosh((-psi) ** 0.5) - 1) / (-psi)
      expected_c3 = (sinh((-psi) ** 0.5) - (-psi) ** 0.5) / (-psi) ** 1.5
  
      assert_allclose(c2(psi), expected_c2, rtol=1e-10)
      assert_allclose(c3(psi), expected_c3, rtol=1e-10)
  
subject: use numpy.testing.assert_allclose with small relative tolerance