def METHOD_NAME(self, ignored: object) -> None:
    """Test mirror dummy user creation for sender when sending to stream"""
    user = self.mit_user("starnine")
    sender_email = "new_sender@mit.edu"
    recipients = ["stream_name"]
    recipient_type_name = "stream"
    client = get_client("zephyr_mirror")
    mirror_sender = create_mirrored_message_users(
        client, user, recipients, sender_email, recipient_type_name
    )
    assert mirror_sender is not None
    self.assertEqual(mirror_sender.email, sender_email)
    self.assertTrue(mirror_sender.is_mirror_dummy)