code: def test_size_strings(dtype):
      # GH#55627
      df = DataFrame({"a": ["a", "a", "b"], "b": "a"}, dtype=dtype)
      result = df.groupby("a")["b"].size()
      exp_dtype = "Int64" if dtype == "string[pyarrow]" else "int64"
      expected = Series(
          [2, 1],
          index=Index(["a", "b"], name="a", dtype=dtype),
          name="b",
          dtype=exp_dtype,
      )
      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 9 for calling a global function with example usage: test_size_strings(dtype) without return types