code: def test_register(self):
      df = self.spark.range(1).selectExpr(
          "array(1, 2, 3) as array",
      )
      str_repr_func = self.spark.udf.register(
          "str_repr", udf(lambda x: str(x), useArrow=True)
      )
  
      # To verify that Arrow optimization is on
      self.assertEqual(
          df.selectExpr("str_repr(array) AS str_id").first()[0],
          "[1, 2, 3]",  # The input is a NumPy array when the Arrow optimization is on
      )
  
      # To verify that a UserDefinedFunction is returned
      self.assertListEqual(
          df.selectExpr("str_repr(array) AS str_id").collect(),
          df.select(str_repr_func("array").alias("str_id")).collect(),
      )
  
imports: import unittest
  from pyspark.errors import PythonException, PySparkNotImplementedError
  from pyspark.sql import Row
  from pyspark.sql.functions import udf
  from pyspark.sql.tests.test_udf import BaseUDFTestsMixin
  from pyspark.sql.types import VarcharType
  from pyspark.testing.sqlutils import have_pandas, have_pyarrow, pandas_requirement_message, pyarrow_requirement_message, ReusedSQLTestCase
  from pyspark.rdd import PythonEvalType
label_desc: Use image node_id 7 for calling the PythonUDFArrowTestsMixin obj's underlying member method code with example usage: obj.test_register() without return types