code: def test_serialize(self, session):
      connection_model_1 = Connection(
          conn_id="mysql_default_1", conn_type="test-type"
      )
      connection_model_2 = Connection(
          conn_id="mysql_default_2", conn_type="test-type2"
      )
      connections = [connection_model_1, connection_model_2]
      session.add_all(connections)
      session.commit()
      instance = ConnectionCollection(
          connections=connections, total_entries=2
      )
      deserialized_connections = connection_collection_schema.dump(
          instance
      )
      assert deserialized_connections == {
          "connections": [
              {
                  "connection_id": "mysql_default_1",
                  "conn_type": "test-type",
                  "description": None,
                  "host": None,
                  "login": None,
                  "schema": None,
                  "port": None,
              },
              {
                  "connection_id": "mysql_default_2",
                  "conn_type": "test-type2",
                  "description": None,
                  "host": None,
                  "login": None,
                  "schema": None,
                  "port": None,
              },
          ],
          "total_entries": 2,
      }
  
imports: from __future__ import annotations
  import re
  import marshmallow
  import pytest
  from airflow.api_connexion.schemas.connection_schema import ConnectionCollection, connection_collection_item_schema, connection_collection_schema, connection_schema, connection_test_schema
  from airflow.models import Connection
  from airflow.utils.session import create_session, provide_session
  from tests.test_utils.db import clear_db_connections
label_desc: Use image node_id 3 for calling the TestConnectionCollectionSchema obj's underlying member method code with example usage: obj.test_serialize(session) without return types