code: def test_merger_not_implemented_error(self):
      # SPARK-39179: Test Merger for error scenarios
      agg = SimpleAggregator(lambda x, y: x + y)
  
      class DummyMerger(Merger):
          def __init__(self, agg):
              Merger.__init__(self, agg)
  
      dummy_merger = DummyMerger(agg)
      with self.assertRaises(NotImplementedError):
          dummy_merger.mergeValues(self.data)
      with self.assertRaises(NotImplementedError):
          dummy_merger.mergeCombiners(self.data)
      with self.assertRaises(NotImplementedError):
          dummy_merger.items()
  
imports: import random
  import unittest
  import tempfile
  import os
  from py4j.protocol import Py4JJavaError
  from pyspark import shuffle, CPickleSerializer, SparkConf, SparkContext
  from pyspark.shuffle import Aggregator, ExternalMerger, ExternalSorter, SimpleAggregator, Merger, ExternalGroupBy
label_desc: Use image node_id 6 for calling the MergerTests obj's underlying member method code with example usage: obj.test_merger_not_implemented_error() without return types