code: def test_groupby_op_with_nullables(na_option):
      # GH 54206
      df = DataFrame({"x": [None]}, dtype="Float64")
      result = df.groupby("x", dropna=False)["x"].rank(
          method="min", na_option=na_option
      )
      expected = Series([1.0], dtype="Float64", name=result.name)
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, NaT, Series, concat
  import pandas._testing
label_desc: Use image node_id 19 for calling a global function with example usage: test_groupby_op_with_nullables(na_option) without return types