'Send a private message from `sender_email` to `receiver_email` and check
that only those two parties actually received the message.'

def assert_personal(self, sender_email, receiver_email, content='test    content'):

    realm = get_realm('zulip')
    sender = get_user(sender_email, realm)
    receiver = get_user(receiver_email, realm)
    sender_messages = message_stream_count(sender)
    receiver_messages = message_stream_count(receiver)
    other_user_profiles = UserProfile.objects.filter(((~ Q(email=sender_email)) & (~ Q(email=receiver_email))))
    old_other_messages = []
    for user_profile in other_user_profiles:
        old_other_messages.append(message_stream_count(user_profile))
    self.send_message(sender_email, receiver_email, Recipient.PERSONAL, content)
    new_other_messages = []
    for user_profile in other_user_profiles:
        new_other_messages.append(message_stream_count(user_profile))
    self.assertEqual(old_other_messages, new_other_messages)
    self.assertEqual(message_stream_count(sender), (sender_messages + 1))
    self.assertEqual(message_stream_count(receiver), (receiver_messages + 1))
    recipient = Recipient.objects.get(type_id=receiver.id, type=Recipient.PERSONAL)
    self.assertEqual(most_recent_message(sender).recipient, recipient)
    self.assertEqual(most_recent_message(receiver).recipient, recipient)
