code: def test_session_transactions_no_null_sessions():
      app = flask.Flask(__name__)
  
      with app.test_client() as c:
          with pytest.raises(RuntimeError) as e:
              with c.session_transaction():
                  pass
          assert "Session backend did not open a session" in str(
              e.value
          )
  
imports: import importlib.metadata
  import click
  import pytest
  import flask
  from flask import appcontext_popped
  from flask.cli import ScriptInfo
  from flask.globals import _cv_request
  from flask.json import jsonify
  from flask.testing import EnvironBuilder
  from flask.testing import FlaskCliRunner
label_desc: Use image node_id 12 for calling a global function with example usage: test_session_transactions_no_null_sessions() without return types