code: def test_rolling_series():
      df = cudf.DataFrame(
          {"a": range(0, 100), "b": [10, 20, 30, 40, 50] * 20}
      )
      pdf = df.to_pandas()
  
      expected = pdf.groupby("b")["a"].rolling(5).mean()
      actual = df.groupby("b")["a"].rolling(5).mean()
  
      assert_eq(expected, actual)
  
imports: import math
  from contextlib import contextmanager
  import numpy
  import pandas
  import pytest
  import cudf
  from cudf.core._compat import PANDAS_GE_150
  from cudf.testing._utils import _create_pandas_series_float64_default, assert_eq
  from cudf.testing.dataset_generator import rand_dataframe
label_desc: Use image node_id 19 for calling a global function with example usage: test_rolling_series() without return types