old_contents: from mock import patch
  import unittest
  
  
  class TestPubSub(unittest.TestCase):
      def test_create_pubsub(self):
          from anypubsub import create_pubsub
          from anypubsub.backends.redis import RedisPubSub
          pubsub = create_pubsub('redis')
          assert isinstance(pubsub, RedisPubSub)
  
      def test_create_pubsub_from_settings(self):
          from anypubsub import create_pubsub_from_settings
          from anypubsub.backends.redis import RedisPubSub
          pubsub = create_pubsub_from_settings({'backend': 'redis'})
          assert isinstance(pubsub, RedisPubSub)
  
      def test_create_pubsub_from_settings_with_prefix(self):
          from anypubsub import create_pubsub_from_settings
          from anypubsub.backends.redis import RedisPubSub
          pubsub = create_pubsub_from_settings({'foo.backend': 'redis'}, prefix='foo.')
          assert isinstance(pubsub, RedisPubSub)
  
      @patch('anypubsub.pubsub._load_entry_point')
      def test_create_nonexistent_pubsub(self, load_entry_point):
          from anypubsub.pubsub import create_pubsub, ConfigurationError
          load_entry_point.return_value = None
          self.assertRaises(ConfigurationError, create_pubsub, 'foobar')
          load_entry_point.assert_called_with('foobar')
  
      @patch('anypubsub.pubsub._load_entry_point')
      def test_create_pubsub_from_entrypoint(self, load_entry_point):
          from anypubsub.pubsub import _load_backend
          load_entry_point.return_value = 'foobar_module'
          result = _load_backend('foobar')
          load_entry_point.assert_called_with('foobar')
          assert result == 'foobar_module'
new_contents: from mock import patch
  import unittest
  
  
  class TestPubSub(unittest.TestCase):
      def test_create_pubsub(self):
          from anypubsub import create_pubsub
          from anypubsub.backends.memory import MemoryPubSub
          pubsub = create_pubsub('memory')
          assert isinstance(pubsub, MemoryPubSub)
  
      def test_create_pubsub_from_settings(self):
          from anypubsub import create_pubsub_from_settings
          from anypubsub.backends.memory import MemoryPubSub
          pubsub = create_pubsub_from_settings({'backend': 'memory'})
          assert isinstance(pubsub, MemoryPubSub)
  
      def test_create_pubsub_from_settings_with_prefix(self):
          from anypubsub import create_pubsub_from_settings
          from anypubsub.backends.memory import MemoryPubSub
          pubsub = create_pubsub_from_settings({'foo.backend': 'memory'}, prefix='foo.')
          assert isinstance(pubsub, MemoryPubSub)
  
      @patch('anypubsub.pubsub._load_entry_point')
      def test_create_nonexistent_pubsub(self, load_entry_point):
          from anypubsub.pubsub import create_pubsub, ConfigurationError
          load_entry_point.return_value = None
          self.assertRaises(ConfigurationError, create_pubsub, 'foobar')
          load_entry_point.assert_called_with('foobar')
  
      @patch('anypubsub.pubsub._load_entry_point')
      def test_create_pubsub_from_entrypoint(self, load_entry_point):
          from anypubsub.pubsub import _load_backend
          load_entry_point.return_value = 'foobar_module'
          result = _load_backend('foobar')
          load_entry_point.assert_called_with('foobar')
          assert result == 'foobar_module'
subject: use memory backend for pubsub creation unit tests