How to use the celery.exceptions.ImproperlyConfigured function in celery

def test_a_path_is_required(self):
        with pytest.raises(ImproperlyConfigured):
            FilesystemBackend(app=self.app)

def test_security_conf(self):
        self.app.conf.task_serializer = 'auth'
        with pytest.raises(ImproperlyConfigured):
            self.app.setup_security()

        self.app.conf.accept_content = ['auth']
        with pytest.raises(ImproperlyConfigured):
            self.app.setup_security()

        _import = builtins.__import__

        def import_hook(name, *args, **kwargs):
            if name == 'cryptography':
                raise ImportError
            return _import(name, *args, **kwargs)

        builtins.__import__ = import_hook
        with pytest.raises(ImproperlyConfigured):
            self.app.setup_security()

def __init__(self, *args, **kwargs):
        """Initialize MongoDB backend instance.

        :raises celery.exceptions.ImproperlyConfigured: if
            module :mod:`pymongo` is not available.

        """
        self.options = {}
        super(MongoBackend, self).__init__(*args, **kwargs)
        self.expires = kwargs.get('expires') or maybe_timedelta(
            self.app.conf.CELERY_TASK_RESULT_EXPIRES)

        if not pymongo:
            raise ImproperlyConfigured(
                'You need to install the pymongo library to use the '
                'MongoDB backend.')

        config = self.app.conf.get('CELERY_MONGODB_BACKEND_SETTINGS')
        if config is not None:
            if not isinstance(config, dict):
                raise ImproperlyConfigured(
                    'MongoDB backend settings should be grouped in a dict')
            config = dict(config)  # do not modify original

            self.host = config.pop('host', self.host)
            self.port = int(config.pop('port', self.port))
            self.user = config.pop('user', self.user)
            self.password = config.pop('password', self.password)
            self.database_name = config.pop('database', self.database_name)
            self.taskmeta_collection = config.pop(

info, left = _settings_info, is_in_old
    else:
        # no settings, just use new format.
        info, left = _settings_info, is_in_old

    if prefix:
        # always use new format if prefix is used.
        info, left = _settings_info, set()

    # only raise error for keys that the user didn't provide two keys
    # for (e.g., both ``result_expires`` and ``CELERY_TASK_RESULT_EXPIRES``).
    really_left = {key for key in left if info.convert[key] not in have}
    if really_left:
        # user is mixing old/new, or new/old settings, give renaming
        # suggestions.
        raise ImproperlyConfigured(info.mix_error.format(renames='\n'.join(
            FMT_REPLACE_SETTING.format(replace=key, with_=info.convert[key])
            for key in sorted(really_left)
        )))

    preconf = {info.convert.get(k, k): v for k, v in items(preconf)}
    defaults = dict(deepcopy(info.defaults), **preconf)
    return Settings(
        preconf, [conf, defaults],
        (_old_key_to_new, _new_key_to_old),
        prefix=prefix,
    )

def by_name(backend=None, loader=None,
            extension_namespace='celery.result_backends'):
    """Get backend class by name/alias."""
    backend = backend or 'disabled'
    loader = loader or current_app.loader
    aliases = dict(BACKEND_ALIASES, **loader.override_backends)
    aliases.update(
        load_extension_class_names(extension_namespace) or {})
    try:
        cls = symbol_by_name(backend, aliases)
    except ValueError as exc:
        reraise(ImproperlyConfigured, ImproperlyConfigured(
            UNKNOWN_BACKEND.strip().format(backend, exc)), sys.exc_info()[2])
    if isinstance(cls, types.ModuleType):
        raise ImproperlyConfigured(UNKNOWN_BACKEND.strip().format(
            backend, 'is a Python module, not a backend class.'))
    return cls

def __init__(self, url=None, *args, **kwargs):
        kwargs.setdefault('expires_type', int)
        super(CouchbaseBackend, self).__init__(*args, **kwargs)
        self.url = url

        if Couchbase is None:
            raise ImproperlyConfigured(
                'You need to install the couchbase library to use the '
                'Couchbase backend.',
            )

        uhost = uport = uname = upass = ubucket = None
        if url:
            _, uhost, uport, uname, upass, ubucket, _ = _parse_url(url)
            ubucket = ubucket.strip('/') if ubucket else None

        config = self.app.conf.get('couchbase_backend_settings', None)
        if config is not None:
            if not isinstance(config, dict):
                raise ImproperlyConfigured(
                    'Couchbase backend settings should be grouped in a dict',
                )
        else:

def __init__(self, servers=None, keyspace=None, table=None, entry_ttl=None,
                 port=9042, **kwargs):
        """Initialize Cassandra backend.

        Raises :class:`celery.exceptions.ImproperlyConfigured` if
        the :setting:`cassandra_servers` setting is not set.

        """
        super(CassandraBackend, self).__init__(**kwargs)

        if not cassandra:
            raise ImproperlyConfigured(E_NO_CASSANDRA)

        conf = self.app.conf
        self.servers = (servers or
                        conf.get('cassandra_servers', None))
        self.port = (port or
                     conf.get('cassandra_port', None))
        self.keyspace = (keyspace or
                         conf.get('cassandra_keyspace', None))
        self.table = (table or
                      conf.get('cassandra_table', None))

        if not self.servers or not self.keyspace or not self.table:
            raise ImproperlyConfigured('Cassandra backend not configured.')

        expires = (entry_ttl or conf.get('cassandra_entry_ttl', None))

super(TyrantBackend, self).__init__(**kwargs)

        if not pytyrant:
            raise ImproperlyConfigured(
                    "You need to install the pytyrant library to use the "
                  + "Tokyo Tyrant backend.")
        self.tyrant_host = (tyrant_host or
                            self.app.conf.get("TT_HOST") or
                            self.tyrant_host)
        self.tyrant_port = (tyrant_port or
                            self.app.conf.get("TT_PORT") or
                            self.tyrant_port)
        if self.tyrant_port:
            self.tyrant_port = int(self.tyrant_port)
        if not self.tyrant_host or not self.tyrant_port:
            raise ImproperlyConfigured(
                "To use the Tokyo Tyrant backend, you have to "
                "set the TT_HOST and TT_PORT settings in your settings.py")
        self._connection = None

def _get_database(self):
        """"Get database from MongoDB connection and perform authentication
        if necessary."""
        if self._database is None:
            conn = self._get_connection()
            db = conn[self.mongodb_database]
            if self.mongodb_user and self.mongodb_password:
                auth = db.authenticate(self.mongodb_user,
                                       self.mongodb_password)
                if not auth:
                    raise ImproperlyConfigured(
                        "Invalid MongoDB username or password.")
            self._database = db

        return self._database

write_cons = conf.get('cassandra_write_consistency') or 'LOCAL_QUORUM'

        self.read_consistency = getattr(
            cassandra.ConsistencyLevel, read_cons,
            cassandra.ConsistencyLevel.LOCAL_QUORUM)
        self.write_consistency = getattr(
            cassandra.ConsistencyLevel, write_cons,
            cassandra.ConsistencyLevel.LOCAL_QUORUM)

        self.auth_provider = None
        auth_provider = conf.get('cassandra_auth_provider', None)
        auth_kwargs = conf.get('cassandra_auth_kwargs', None)
        if auth_provider and auth_kwargs:
            auth_provider_class = getattr(cassandra.auth, auth_provider, None)
            if not auth_provider_class:
                raise ImproperlyConfigured(E_NO_SUCH_CASSANDRA_AUTH_PROVIDER)
            self.auth_provider = auth_provider_class(**auth_kwargs)

        self._connection = None
        self._session = None
        self._write_stmt = None
        self._read_stmt = None
        self._make_stmt = None