code: def __test_merge_error(
      self,
      error_class,
      error_message_regex,
      left=None,
      right=None,
      by=["id"],
      fn=lambda lft, rgt: pd.merge(lft, rgt, on=["id", "k"]),
      output_schema="id long, k int, v int, v2 int",
  ):
      # Test fn as is, cf. _test_merge_error
      with self.assertRaisesRegex(error_class, error_message_regex):
          self.__test_merge(left, right, by, fn, output_schema)
  
imports: import unittest
  from typing import cast
  from pyspark.sql.functions import array, explode, col, lit, udf, pandas_udf, sum
  from pyspark.sql.types import ArrayType, DoubleType, LongType, StructType, StructField, YearMonthIntervalType, Row
  from pyspark.sql.window import Window
  from pyspark.errors import IllegalArgumentException, PythonException
  from pyspark.testing.sqlutils import ReusedSQLTestCase, have_pandas, have_pyarrow, pandas_requirement_message, pyarrow_requirement_message
  from pyspark.testing.utils import QuietTest
label_desc: Use image node_id 43 for calling the CogroupedApplyInPandasTestsMixin obj's underlying member method code with example usage: obj.__test_merge_error(error_class, error_message_regex, left, right, by, fn, output_schema) without return types