code: def test_spikes_categorical_color_op(self):
      spikes = Spikes(
          [(0, 0, "A"), (0, 1, "B"), (0, 2, "A")], vdims=["y", "color"]
      ).opts(color="color")
      plot = mpl_renderer.get_plot(spikes)
      artist = plot.handles["artist"]
      self.assertEqual(
          np.asarray(artist.get_array()), np.array([0, 1, 0])
      )
      self.assertEqual(artist.get_clim(), (0, 1))
  
imports: import numpy
  import pytest
  from holoviews.core.options import AbbreviatedException
  from holoviews.core.overlay import NdOverlay
  from holoviews.core.spaces import HoloMap
  from holoviews.element import Spikes
  from ..utils import ParamLogStream
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 15 for calling the TestSpikesPlot obj's underlying member method code with example usage: obj.test_spikes_categorical_color_op() without return types