code: def test_fontsize(self):
      df = DataFrame({"a": [1, 2, 3, 4, 5, 6]})
      _check_ticks_props(
          df.boxplot("a", fontsize=16), xlabelsize=16, ylabelsize=16
      )
  
imports: import itertools
  import string
  import numpy
  import pytest
  from pandas import DataFrame, MultiIndex, Series, date_range, plotting, timedelta_range
  import pandas._testing
  from pandas.tests.plotting.common import _check_axes_shape, _check_box_return_type, _check_plot_works, _check_ticks_props, _check_visible
  from pandas.io.formats.printing import pprint_thing
label_desc: Use image node_id 16 for calling the TestDataFramePlots obj's underlying member method code with example usage: obj.test_fontsize() without return types