text: import pytest
  import unittest
  
  from betamax import Betamax, cassette
  from requests import Session
  
  
  class TestCassetteRecordMode(unittest.TestCase):
      def setUp(self):
          with Betamax.configure() as config:
              config.default_cassette_options['record_mode'] = 'none'
  
      def tearDown(self):
          with Betamax.configure() as config:
              config.default_cassette_options['record_mode'] = 'once'
  
      def test_record_mode_is_none(self):
          s = Session()
          with pytest.raises(ValueError):
              with Betamax(s) as recorder:
                  recorder.use_cassette('regression_record_mode')
                  assert recorder.current_cassette is None
  
      def test_class_variables_retain_their_value(self):
          opts = cassette.Cassette.default_cassette_options
          assert opts['record_mode'] == 'none'
  