code: def test_mock_movielens_schema__get_spark_df__data_serialization_default_param(
      spark, mocker: MockerFixture
  ):
      data_size = 3
      to_csv_spy = mocker.spy(pandas.DataFrame, "to_csv")
  
      df = MockMovielensSchema.get_spark_df(spark, size=data_size)
      # assertions
      to_csv_spy.assert_called_once()
      assert df.count() == data_size
  
imports: import os
  import gc
  import pandas
  from pandas.core.series import Series
  import pytest
  from pytest_mock import MockerFixture
  from recommenders.utils.constants import DEFAULT_GENRE_COL, DEFAULT_TITLE_COL
  from recommenders.datasets.movielens import MockMovielensSchema
  from recommenders.datasets.movielens import load_pandas_df, load_spark_df, load_item_df, download_movielens, extract_movielens
  from recommenders.datasets.movielens import DATA_FORMAT, MOCK_DATA_FORMAT, DEFAULT_HEADER, DEFAULT_ITEM_COL, DEFAULT_USER_COL
label_desc: Use image node_id 13 for calling a global function with example usage: test_mock_movielens_schema__get_spark_df__data_serialization_default_param(spark, mocker) without return types