code: def testDC(self):
      inputSize = 512
      signalDC = [1] * inputSize
      expectedDC = [0] * int(inputSize / 2 + 1)
      expectedDC[0] = inputSize
      outputDC = Spectrum()(signalDC)
      self.assertEqualVector(outputDC, expectedDC)
  
file_path: essentia/test/src/unittests/standard/test_spectrum.py
imports: from essentia_test import *
label_desc: Use image node_id 2 for calling the TestSpectrum obj's underlying member method code with example usage: obj.testDC() without return types