code: def test_size_groupby_all_null():
      # https://github.com/pandas-dev/pandas/issues/23050
      # Assert no 'Value Error : Length of passed values is 2, index implies 0'
      df = DataFrame({"A": [None, None]})  # all-null groups
      result = df.groupby("A").size()
      expected = Series(dtype="int64", index=Index([], name="A"))
      tm.assert_series_equal(result, expected)
  
file_path: pandas/pandas/tests/groupby/methods/test_size.py
imports: import numpy
  import pytest
  import pandas.util._test_decorators
  from pandas.core.dtypes.common import is_integer_dtype
  from pandas import DataFrame, Index, PeriodIndex, Series
  import pandas._testing
label_desc: Use image node_id 5 for calling a global function with example usage: test_size_groupby_all_null() without return types