code: def test__setitem__adds_empty_string_value(self):
      assert "test" not in self.query_params
      self.query_params["test"] = ""
      assert self.query_params["test"] == ""
      message = self.get_message_from_queue(0)
      assert (
          "foo=bar&two=x&two=y&test="
          == message.page_info_changed.query_string
      )
  
imports: import pytest
  from streamlit.errors import StreamlitAPIException
  from streamlit.runtime.state.query_params import QueryParams
  from tests.delta_generator_test_case import DeltaGeneratorTestCase
label_desc: Use image node_id 11 for calling the QueryParamsMethodTests obj's underlying member method code with example usage: obj.test__setitem__adds_empty_string_value() without return types