code: def testDC(self):
      # input is [1, 0, 0, ...] which corresponds to an FFT of constant magnitude 1
      signalSize = 512
      fftSize = int(signalSize / 2) + 1
  
      signalDC = zeros(signalSize).astype(numpy.complex64)
      signalDC[0] = 1.0 + 0j
  
      expected = [1 + 0j] * fftSize
  
      self.assertAlmostEqualVector(FFTC()(signalDC), expected)
  
file_path: essentia/test/src/unittests/standard/test_fftc.py
imports: from essentia_test import *
  import math
label_desc: Use image node_id 1 for calling the TestFFT obj's underlying member method code with example usage: obj.testDC() without return types