code: def test_single_spectrum_helper_unsupported_modes(self, mode):
      with pytest.raises(ValueError):
          mlab._single_spectrum_helper(x=self.y, mode=mode)
  
imports: from numpy.testing import assert_allclose, assert_almost_equal, assert_array_equal, assert_array_almost_equal_nulp
  import numpy
  import pytest
  from matplotlib import mlab
label_desc: Use image node_id 5 for calling the TestSpectral obj's underlying member method code with example usage: obj.test_single_spectrum_helper_unsupported_modes(mode) without return types