code: def test_where_categorical_filtering(self):
      # GH#22609 Verify filtering operations on DataFrames with categorical Series
      df = DataFrame(data=[[0, 0], [1, 1]], columns=["a", "b"])
      df["b"] = df["b"].astype("category")
  
      result = df.where(df["a"] > 0)
      # Explicitly cast to 'float' to avoid implicit cast when setting np.nan
      expected = df.copy().astype({"a": "float"})
      expected.loc[0, :] = np.nan
  
      tm.assert_equal(result, expected)
  
imports: from datetime import datetime
  from hypothesis import given
  import numpy
  import pytest
  from pandas.core.dtypes.common import is_scalar
  import pandas
  from pandas import DataFrame, DatetimeIndex, Index, Series, StringDtype, Timestamp, date_range, isna
  import pandas._testing
  from pandas._testing._hypothesis import OPTIONAL_ONE_OF_ALL
label_desc: Use image node_id 27 for calling the TestDataFrameIndexingWhere obj's underlying member method code with example usage: obj.test_where_categorical_filtering() without return types