code: def testRegression(self):
      # Simple regression test, comparing normal behaviour
      audio = MonoLoader(
          filename=join(
              testdata.audio_dir,
              "generated/synthesised/sin440_sweep_0db.wav",
          ),
          sampleRate=44100,
      )()
  
      fft = Spectrum()
      window = Windowing(type="hamming")
      fbands = FrequencyBands(sampleRate=44100)
  
      for frame in FrameGenerator(audio, frameSize=2048, hopSize=512):
          bands = fbands(fft(window(frame)))
  
          self.assert_(not any(numpy.isnan(bands)))
          self.assert_(not any(numpy.isinf(bands)))
          self.assert_(all(bands >= 0.0))
  
      # input is a flat spectrum:
      input = [1] * 1024
      sr = 44100.0
      binfreq = 0.5 * sr / (len(input) - 1)
      fbands = [8 * x * binfreq for x in range(4)]
      expected = [8, 8, 8]
      output = FrequencyBands(frequencyBands=fbands)(input)
  
      self.assertEqualVector(output, expected)
  
imports: from essentia_test import *
label_desc: Use image node_id 1 for calling the TestFrequencyBands obj's underlying member method code with example usage: obj.testRegression() without return types