docstr: check the transform of zeros is all zeros 
docstr_tok: ["check","the","transform","of","zeros","is","all","zeros"]
code: def test_zeros(self):
      """check the transform of zeros is all zeros"""
      win_s = 512
      timegrain = fvec(win_s)
      f = fft(win_s)
      fftgrain = f(timegrain)
      assert_equal(fftgrain.norm, 0)
      try:
          assert_equal(fftgrain.phas, 0)
      except AssertionError:
          assert_equal(fftgrain.phas[fftgrain.phas > 0], +pi)
          assert_equal(fftgrain.phas[fftgrain.phas < 0], -pi)
          assert_equal(
              np.abs(fftgrain.phas[np.abs(fftgrain.phas) != pi]), 0
          )
          self.skipTest(
              "fft(fvec(%d)).phas != +0, " % win_s
              + "This is expected when using fftw3 on powerpc."
          )
  
imports: from numpy.testing import TestCase
  from numpy.testing import assert_equal, assert_almost_equal
  import numpy
  from aubio import fvec, fft, cvec
  from math import pi, floor
  from random import random
label_desc: Use image node_id 3 for calling the aubio_fft_test_case obj's underlying member method code with example usage: obj.test_zeros() without return types