code: def test_violin_simple(self):
      values = np.random.rand(100)
      violin = Violin(values)
      plot = mpl_renderer.get_plot(violin)
      data, style, axis_opts = plot.get_data(violin, {}, {})
      self.assertEqual(data[0][0], values)
      self.assertEqual(style["positions"], [0])
      self.assertEqual(style["labels"], [""])
  
file_path: holoviews/holoviews/tests/plotting/matplotlib/test_violinplot.py
imports: import numpy
  from holoviews.element import Violin
  from .test_plot import TestMPLPlot, mpl_renderer
label_desc: Use image node_id 1 for calling the TestMPLViolinPlot obj's underlying member method code with example usage: obj.test_violin_simple() without return types