def testParsingMerge(self):
    """Check the merge behavior when a required or optional field appears
    multiple times in the input."""
    messages = [
        unittest_pb2.TestAllTypes(),
        unittest_pb2.TestAllTypes(),
        unittest_pb2.TestAllTypes() ]
    messages[0].optional_int32 = 1
    messages[1].optional_int64 = 2
    messages[2].optional_int32 = 3
    messages[2].optional_string = 'hello'

    merged_message = unittest_pb2.TestAllTypes()
    merged_message.optional_int32 = 3
    merged_message.optional_int64 = 2
    merged_message.optional_string = 'hello'

    generator = unittest_pb2.TestParsingMerge.RepeatedFieldsGenerator()
    generator.field1.extend(messages)
    generator.field2.extend(messages)
    generator.field3.extend(messages)
    generator.ext1.extend(messages)
    generator.ext2.extend(messages)
    generator.group1.add().field1.MergeFrom(messages[0])
    generator.group1.add().field1.MergeFrom(messages[1])
    generator.group1.add().field1.MergeFrom(messages[2])
    generator.group2.add().field1.MergeFrom(messages[0])
    generator.group2.add().field1.MergeFrom(messages[1])
    generator.group2.add().field1.MergeFrom(messages[2])

    data = generator.SerializeToString()
    parsing_merge = unittest_pb2.TestParsingMerge()
    parsing_merge.ParseFromString(data)

    # Required and optional fields should be merged.
    self.assertEqual(parsing_merge.required_all_types, merged_message)
    self.assertEqual(parsing_merge.optional_all_types, merged_message)
    self.assertEqual(parsing_merge.optionalgroup.optional_group_all_types,
                     merged_message)
    self.assertEqual(parsing_merge.Extensions[
                     unittest_pb2.TestParsingMerge.optional_ext],
                     merged_message)

    # Repeated fields should not be merged.
    self.assertEqual(len(parsing_merge.repeated_all_types), 3)
    self.assertEqual(len(parsing_merge.repeatedgroup), 3)
    self.assertEqual(len(parsing_merge.Extensions[
        unittest_pb2.TestParsingMerge.repeated_ext]), 3)