code: def test_count(
      self, mock_load_dataset, mock_get_operator, mock_operator_exists
  ):
      dataset_id = ObjectId()
      dataset_name = f"test_dataset_{dataset_id}"
      mock_load_dataset.return_value.name = dataset_name
      mock_load_dataset.return_value._doc.id = dataset_id
  
      mock_get_operator.return_value = MockOperator()
  
      delegation_target = f"delegation_target{ObjectId()}"
      for i in range(4):
          operator = f"@voxelfiftyone/operator/test_{i}"
          for j in range(25):
              doc = self.svc.queue_operation(
                  operator=operator,
                  delegation_target=delegation_target,
                  label=mock_get_operator.return_value.name,
                  context=ExecutionContext(
                      request_params={
                          "foo": "bar",
                          "dataset_name": dataset_name,
                      }
                  ),
              )
              time.sleep(
                  0.01
              )  # ensure that the queued_at times are different
              self.docs_to_delete.append(doc)
  
      # test paging - get a page of everything
      docs = self.svc.count(
          search={"operator/test": {"operator"}},
      )
  
      self.assertEqual(docs, 100)
  
      docs = self.svc.count(
          search={"test_0": {"operator"}},
      )
  
      self.assertEqual(docs, 25)
  
      docs = self.svc.count(
          filters={"operator": f"@voxelfiftyone/operator/test_0"},
      )
      self.assertEqual(docs, 25)
  
imports: import time
  import unittest
  from unittest import mock
  from unittest.mock import patch
  import pytest
  import fiftyone
  from bson import ObjectId
  from fiftyone import Dataset
  from fiftyone.factory import DelegatedOperationPagingParams, SortDirection, SortByField
  from fiftyone.operators.delegated import DelegatedOperationService
  from fiftyone.operators.executor import ExecutionContext, ExecutionResult, ExecutionRunState, ExecutionProgress
  from fiftyone.operators.operator import Operator, OperatorConfig
label_desc: Use image node_id 20 for calling the DelegatedOperationServiceTests obj's underlying member method code with example usage: obj.test_count(mock_load_dataset, mock_get_operator, mock_operator_exists) without return types