code: def test_has_externally_shared_axis_invalid_compare_axis(self):
      # GH33819
      # Test _has_externally_shared_axis() raises an exception when
      # passed an invalid value as compare_axis parameter
      func = plotting._matplotlib.tools._has_externally_shared_axis
  
      fig = mpl.pyplot.figure()
      plots = fig.subplots(4, 2)
  
      # Create arbitrary axes
      plots[0][0] = fig.add_subplot(321, sharey=plots[0][1])
  
      # Check that an invalid compare_axis value triggers the expected exception
      msg = "needs 'x' or 'y' as a second parameter"
      with pytest.raises(ValueError, match=msg):
          func(plots[0][0], "z")
  
imports: import os
  import numpy
  import pytest
  import pandas.util._test_decorators
  from pandas import DataFrame, Index, Series, Timestamp, date_range, interval_range, period_range, plotting, read_csv
  import pandas._testing
  from pandas.tests.plotting.common import _check_colors, _check_legend_labels, _check_plot_works, _check_text_labels, _check_ticks_props
label_desc: Use image node_id 31 for calling the TestDataFramePlots obj's underlying member method code with example usage: obj.test_has_externally_shared_axis_invalid_compare_axis() without return types