code: def test_group_by_empty_groups(
      aggregation: str,
      args: list[object],
      expected_values: list[object],
      expected_dtype: pl.DataType,
  ) -> None:
      df = pl.DataFrame({"a": [1, 2], "b": [1, 2]})
      result = df.group_by("b", maintain_order=True).agg(
          getattr(pl.col("a").filter(pl.col("b") != 2), aggregation)(
              *args
          )
      )
      expected = pl.DataFrame(
          {"b": [1, 2], "a": expected_values}
      ).with_columns(pl.col("a").cast(expected_dtype))
      assert_frame_equal(result, expected)
  
imports: from __future__ import annotations
  from collections import OrderedDict
  from datetime import datetime, timedelta
  from typing import Any
  import pytest
  import polars
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 26 for calling a global function with example usage: test_group_by_empty_groups(aggregation, args, expected_values, expected_dtype) without return types