code: def test_image_cbar_extend_max(self):
      img = Image(np.array([[0, 1], [2, 3]])).redim(
          z=dict(range=(None, 2))
      )
      plot = mpl_renderer.get_plot(img.opts(colorbar=True))
      assert plot.handles["cbar"].extend == "max"
  
file_path: holoviews/holoviews/tests/plotting/matplotlib/test_rasterplot.py
imports: from unittest import SkipTest
  import numpy
  from matplotlib.colors import ListedColormap
  from holoviews.element import Image, ImageStack, Raster
  from holoviews.plotting.mpl.raster import RGBPlot
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 8 for calling the TestRasterPlot obj's underlying member method code with example usage: obj.test_image_cbar_extend_max() without return types