docstr: Test correct computation of extents.
  
          
docstr_tok: ["Test","correct","computation","of","extents","."]
code: def test_plot_extents(self):
      """Test correct computation of extents."""
  
      extents = self.plot.get_extents("", "")
      self.assertEqual(extents, (-0.2, -0.2, 2.2, 2.2))
  
imports: from itertools import product
  import numpy
  from bokeh.models import ColorBar
  from holoviews.core.spaces import HoloMap
  from holoviews.element.raster import HeatMap
  from holoviews.plotting.bokeh import RadialHeatMapPlot
  from .test_plot import TestBokehPlot, bokeh_renderer
label_desc: Use image node_id 4 for calling the BokehRadialHeatMapPlotTests obj's underlying member method code with example usage: obj.test_plot_extents() without return types