SNOW-3153913: patching split() in local testing

[serban-dobroiu]

Hi, trying to patch and use split() for testing some dataframe transformations but I'm not sure I'm doing it right:

@patch(split)
def mock_split(column: ColumnEmulator, pattern: ColumnEmulator) -> ColumnEmulator:
    ret_column = ColumnEmulator(data=[split(row, pattern=pattern) for row in column])
    ret_column.sf_type = ColumnType(ArrayType(StringType()), nullable=True)
    return ret_column

When I try to test a transformation function calling split():

def col_to_array(
    df: DataFrame,
    cols: Iterable[str],
    delimiter: str = "|",
    ignore_missing: bool = False,
) -> DataFrame:
....
for _col in cols:
        transformation = when(col(_col).is_not_null(), split(col(_col), lit(delimiter)))
....

it is throwing the following type error:

error_message = "Error executing mocked function 'split'. See error traceback for detailed information."```

Can you please help me understand what is happening here?

thank you!

[sfc-gh-sghosh]

Hello @serban-dobroiu ,

Thanks for raising the issue. Could you please share the import libraries as well? Which version of Snowpark Python are you using, which verison of python ?

[serban-dobroiu]

@sfc-gh-sghosh sorry about that

• here are the imports

import pytest
from unittest.mock import MagicMock, create_autospec
from snowflake.snowpark import Session
from snowflake.snowpark.dataframe import DataFrame
from snowflake.snowpark.types import (
    ArrayType,
    StructType,
    StructField,
    StringType,
    IntegerType,
    FloatType,
)
from snowflake.snowpark.functions import split
from snowflake.snowpark.mock import patch, ColumnEmulator, ColumnType
from snowflake.snowpark.testing import assert_dataframe_equal
from utilities.transformation_functions import col_to_array


# add parent to Path
import sys
from pathlib import Path

and Python 3.11.5 and Snowflake Snowpark Python 1.44.0

Thank you!