code: def test_subplots_warnings(self, idx):
      # GH 9464
      with tm.assert_produces_warning(None):
          df = DataFrame(
              np.random.default_rng(2).standard_normal((5, 4)),
              index=idx,
          )
          df.plot(subplots=True, layout=(3, 2))
  
imports: import string
  import numpy
  import pytest
  from pandas.compat import is_platform_linux
  from pandas.compat.numpy import np_version_gte1p24
  import pandas
  from pandas import DataFrame, Series, date_range
  import pandas._testing
  from pandas.tests.plotting.common import _check_axes_shape, _check_box_return_type, _check_legend_labels, _check_ticks_props, _check_visible, _flatten_visible
  from pandas.io.formats.printing import pprint_thing
label_desc: Use image node_id 12 for calling the TestDataFramePlotsSubplots obj's underlying member method code with example usage: obj.test_subplots_warnings(idx) without return types