code: def test_auto(self, xp, scp):
      # Test bode() magnitude calculation.
      # 1st order low-pass filter: H(s) = 0.3 / (z - 0.2),
      system = scp.signal.TransferFunction(0.3, [1, -0.2], dt=0.1)
      w = xp.array([0.1, 0.5, 1, pi])
      w2, mag, phase = scp.signal.dbode(system, w=w)
      return w2, mag, phase
  
imports: from math import sqrt, pi
  from pytest import raises
  import cupy
  from cupy import testing
  import cupyx.scipy.signal
label_desc: Use image node_id 2 for calling the Test_bode obj's underlying member method code with example usage: obj.test_auto(xp, scp) and returns: w2,  mag,  phase