code: def test_bandwidth_zero(self):
      kern = kernels.Gaussian()
      for bw in ["scott", "silverman", "normal_reference"]:
          with pytest.raises(
              RuntimeError, match="Selected KDE bandwidth is 0"
          ):
              select_bandwidth(self.xx, bw, kern)
  
imports: import numpy
  from scipy import stats
  from statsmodels.sandbox.nonparametric import kernels
  from statsmodels.distributions.mixture_rvs import mixture_rvs
  from statsmodels.nonparametric.bandwidths import select_bandwidth
  from statsmodels.nonparametric.bandwidths import bw_normal_reference
  from numpy.testing import assert_allclose
  import pytest
label_desc: Use image node_id 1 for calling the BandwidthZero obj's underlying member method code with example usage: obj.test_bandwidth_zero() without return types