code: def test_sankey_simple(self):
      sankey = Sankey(
          [
              ("A", "X", 5),
              ("A", "Y", 7),
              ("A", "Z", 6),
              ("B", "X", 2),
              ("B", "Y", 9),
              ("B", "Z", 4),
          ]
      )
      plot = mpl_renderer.get_plot(sankey)
  
      rects = plot.handles["rects"]
      labels = plot.handles["labels"]
  
      text_data = {
          "x": np.array([18.75, 18.75, 1003.75, 1003.75, 1003.75]),
          "y": np.array(
              [125.454545, 375.454545, 48.787879, 229.090909, 430.30303]
          ),
          "text": ["A - 18", "B - 15", "X - 7", "Y - 16", "Z - 10"],
      }
      for i, text in enumerate(labels):
          self.assertEqual(text.xy[0], text_data["x"][i])
          self.assertEqual(text.xy[1], text_data["y"][i])
          self.assertEqual(text.get_text(), text_data["text"][i])
  
      quad_data = {
          "x0": [0, 0, 985.0, 985.0, 985.0],
          "x1": [15, 15, 1000.0, 1000.0, 1000.0],
          "y0": [
              0.0,
              270.9090909090908,
              -7.105427357601002e-15,
              117.57575757575756,
              360.6060606060606,
          ],
          "y1": [250.909091, 480.0, 97.575758, 340.606061, 500.0],
      }
      for i, rect in enumerate(rects.get_paths()):
          x0, x1, y0, y1 = (
              quad_data[c][i] for c in ("x0", "x1", "y0", "y1")
          )
          arr = np.array(
              [[x0, y0], [x1, y0], [x1, y1], [x0, y1], [x0, y0]]
          )
          self.assertEqual(rect.vertices, arr)
  
file_path: holoviews/holoviews/tests/plotting/matplotlib/test_sankey.py
imports: import numpy
  from holoviews.core.data import Dataset
  from holoviews.element import Sankey
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 1 for calling the TestSankeyPlot obj's underlying member method code with example usage: obj.test_sankey_simple() without return types