code: def test_valid_req(self, service):
      (
          headers,
          input_batch,
          req_to_id_map,
      ) = service.retrieve_data_for_inference(self.data)
      assert (
          headers[0].get_request_property("xyz").get("content-type")
          == "text/csv"
      )
      assert input_batch[0] == {"xyz": "abc"}
      assert req_to_id_map == {0: "123"}
  
file_path: serve/ts/tests/unit_tests/test_worker_service.py
imports: import logging
  import os
  import pytest
  from ts.context import Context
  from ts.service import Service
  from ts.service import emit_metrics
  from ts.metrics.metric_cache_yaml_impl import MetricsCacheYamlImpl
label_desc: Use image node_id 4 for calling the TestService obj's underlying member method code with example usage: obj.test_valid_req(service) without return types