Update type hints to appease Pylance and stricter mypy settings

16 files changed, 89 insertions, 58 deletions

diff --git a/requests_cache/_utils.py b/requests_cache/_utils.py
index ea6948f..4dbc4ec 100644
--- a/requests_cache/_utils.py
+++ b/requests_cache/_utils.py
@@ -7,9 +7,9 @@ KwargDict = Dict[str, Any]
 logger = getLogger('requests_cache')
 
 
-def chunkify(iterable: Iterable, max_size: int) -> Iterator[List]:
+def chunkify(iterable: Optional[Iterable], max_size: int) -> Iterator[List]:
     """Split an iterable into chunks of a max size"""
-    iterable = list(iterable)
+    iterable = list(iterable or [])
     for index in range(0, len(iterable), max_size):
         yield iterable[index : index + max_size]
 
@@ -35,7 +35,7 @@ def encode(value, encoding='utf-8') -> bytes:
     return value if isinstance(value, bytes) else str(value).encode(encoding)
 
 
-def get_placeholder_class(original_exception: Exception = None):
+def get_placeholder_class(original_exception: Optional[Exception] = None):
     """Create a placeholder type for a class that does not have dependencies installed.
     This allows delaying ImportErrors until init time, rather than at import time.
     """
@@ -58,14 +58,16 @@ def get_placeholder_class(original_exception: Exception = None):
     return Placeholder
 
 
-def get_valid_kwargs(func: Callable, kwargs: Dict, extras: Iterable[str] = None) -> KwargDict:
+def get_valid_kwargs(
+    func: Callable, kwargs: Dict, extras: Optional[Iterable[str]] = None
+) -> KwargDict:
     """Get the subset of non-None ``kwargs`` that are valid arguments for ``func``"""
     kwargs, _ = split_kwargs(func, kwargs, extras)
     return {k: v for k, v in kwargs.items() if v is not None}
 
 
 def split_kwargs(
-    func: Callable, kwargs: Dict, extras: Iterable[str] = None
+    func: Callable, kwargs: Dict, extras: Optional[Iterable[str]] = None
 ) -> Tuple[KwargDict, KwargDict]:
     """Split ``kwargs`` into two dicts: those that are valid arguments for ``func``,  and those that
     are not
diff --git a/requests_cache/backends/__init__.py b/requests_cache/backends/__init__.py
index 9dd206a..d916ab8 100644
--- a/requests_cache/backends/__init__.py
+++ b/requests_cache/backends/__init__.py
@@ -56,7 +56,9 @@ BACKEND_CLASSES = {
 }
 
 
-def init_backend(cache_name: str, backend: BackendSpecifier = None, **kwargs) -> BaseCache:
+def init_backend(
+    cache_name: str, backend: Optional[BackendSpecifier] = None, **kwargs
+) -> BaseCache:
     """Initialize a backend from a name, class, or instance"""
     logger.debug(f'Initializing backend: {backend} {cache_name}')
 
diff --git a/requests_cache/backends/base.py b/requests_cache/backends/base.py
index efbd214..cca234a 100644
--- a/requests_cache/backends/base.py
+++ b/requests_cache/backends/base.py
@@ -73,7 +73,12 @@ class BaseCache:
         except (AttributeError, KeyError):
             return default
 
-    def save_response(self, response: Response, cache_key: str = None, expires: datetime = None):
+    def save_response(
+        self,
+        response: Response,
+        cache_key: Optional[str] = None,
+        expires: Optional[datetime] = None,
+    ):
         """Save a response to the cache
 
         Args:
@@ -101,10 +106,13 @@ class BaseCache:
         self.redirects.close()
 
     def create_key(
-        self, request: AnyRequest = None, match_headers: Iterable[str] = None, **kwargs
+        self,
+        request: AnyRequest,
+        match_headers: Optional[Iterable[str]] = None,
+        **kwargs,
     ) -> str:
         """Create a normalized cache key from a request object"""
-        key_fn = self._settings.key_fn or create_key
+        key_fn = self._settings.key_fn if self._settings.key_fn is not None else create_key
         return key_fn(
             request=request,
             ignored_parameters=self._settings.ignored_parameters,
@@ -118,9 +126,9 @@ class BaseCache:
 
     def contains(
         self,
-        key: str = None,
-        request: AnyRequest = None,
-        url: str = None,
+        key: Optional[str] = None,
+        request: Optional[AnyRequest] = None,
+        url: Optional[str] = None,
     ):
         """Check if the specified request is cached
 
@@ -141,8 +149,8 @@ class BaseCache:
         expired: bool = False,
         invalid: bool = False,
         older_than: ExpirationTime = None,
-        requests: Iterable[AnyRequest] = None,
-        urls: Iterable[str] = None,
+        requests: Optional[Iterable[AnyRequest]] = None,
+        urls: Optional[Iterable[str]] = None,
     ):
         """Remove responses from the cache according one or more conditions.
 
@@ -355,7 +363,7 @@ class BaseStorage(MutableMapping[KT, VT], ABC):
 
     def __init__(
         self,
-        serializer: SerializerType = None,
+        serializer: Optional[SerializerType] = None,
         no_serializer: bool = False,
         decode_content: bool = False,
         **kwargs,
diff --git a/requests_cache/backends/dynamodb.py b/requests_cache/backends/dynamodb.py
index e5f0c4b..721e256 100644
--- a/requests_cache/backends/dynamodb.py
+++ b/requests_cache/backends/dynamodb.py
@@ -4,7 +4,7 @@
    :classes-only:
    :nosignatures:
 """
-from typing import Dict, Iterable
+from typing import Dict, Iterable, Optional
 
 import boto3
 from boto3.dynamodb.types import Binary
@@ -33,7 +33,7 @@ class DynamoDbCache(BaseCache):
         self,
         table_name: str = 'http_cache',
         ttl: bool = True,
-        connection: ServiceResource = None,
+        connection: Optional[ServiceResource] = None,
         decode_content: bool = True,
         **kwargs,
     ):
@@ -75,7 +75,7 @@ class DynamoDbDict(BaseStorage):
         table_name: str,
         namespace: str,
         ttl: bool = True,
-        connection: ServiceResource = None,
+        connection: Optional[ServiceResource] = None,
         **kwargs,
     ):
         super().__init__(**kwargs)
diff --git a/requests_cache/backends/filesystem.py b/requests_cache/backends/filesystem.py
index a349dae..cc57597 100644
--- a/requests_cache/backends/filesystem.py
+++ b/requests_cache/backends/filesystem.py
@@ -10,7 +10,7 @@ from pathlib import Path
 from pickle import PickleError
 from shutil import rmtree
 from threading import RLock
-from typing import Iterator
+from typing import Iterator, Optional
 
 from ..serializers import SERIALIZERS, json_serializer
 from . import BaseCache, BaseStorage
@@ -75,7 +75,7 @@ class FileDict(BaseStorage):
         cache_name: AnyPath,
         use_temp: bool = False,
         use_cache_dir: bool = False,
-        extension: str = None,
+        extension: Optional[str] = None,
         **kwargs,
     ):
         super().__init__(**kwargs)
@@ -133,7 +133,7 @@ class FileDict(BaseStorage):
             return self.cache_dir.glob(f'*{self.extension}')
 
 
-def _get_extension(extension: str = None, serializer=None) -> str:
+def _get_extension(extension: Optional[str] = None, serializer=None) -> str:
     """Use either the provided file extension, or get the serializer's default extension"""
     if extension:
         return f'.{extension}'
diff --git a/requests_cache/backends/mongodb.py b/requests_cache/backends/mongodb.py
index c719aa7..e15e331 100644
--- a/requests_cache/backends/mongodb.py
+++ b/requests_cache/backends/mongodb.py
@@ -83,7 +83,7 @@ class MongoDict(BaseStorage):
         self,
         db_name: str,
         collection_name: str = 'http_cache',
-        connection: MongoClient = None,
+        connection: Optional[MongoClient] = None,
         **kwargs,
     ):
         super().__init__(**kwargs)
diff --git a/requests_cache/backends/redis.py b/requests_cache/backends/redis.py
index 259b858..fef488c 100644
--- a/requests_cache/backends/redis.py
+++ b/requests_cache/backends/redis.py
@@ -5,7 +5,7 @@
    :nosignatures:
 """
 from logging import getLogger
-from typing import Iterable
+from typing import Iterable, Optional
 
 from redis import Redis, StrictRedis
 
@@ -32,7 +32,7 @@ class RedisCache(BaseCache):
     def __init__(
         self,
         namespace='http_cache',
-        connection: Redis = None,
+        connection: Optional[Redis] = None,
         ttl: bool = True,
         ttl_offset: int = DEFAULT_TTL_OFFSET,
         **kwargs,
@@ -62,7 +62,7 @@ class RedisDict(BaseStorage):
     def __init__(
         self,
         namespace: str,
-        collection_name: str = None,
+        collection_name: Optional[str] = None,
         connection=None,
         ttl: bool = True,
         ttl_offset: int = DEFAULT_TTL_OFFSET,
@@ -144,7 +144,11 @@ class RedisHashDict(BaseStorage):
     """
 
     def __init__(
-        self, namespace: str = 'http_cache', collection_name: str = None, connection=None, **kwargs
+        self,
+        namespace: str = 'http_cache',
+        collection_name: Optional[str] = None,
+        connection=None,
+        **kwargs,
     ):
         super().__init__(**kwargs)
         connection_kwargs = get_valid_kwargs(Redis, kwargs)
diff --git a/requests_cache/backends/sqlite.py b/requests_cache/backends/sqlite.py
index f936a77..7a99a39 100644
--- a/requests_cache/backends/sqlite.py
+++ b/requests_cache/backends/sqlite.py
@@ -13,7 +13,7 @@ from os.path import getsize, isfile
 from pathlib import Path
 from tempfile import gettempdir
 from time import time
-from typing import Collection, Iterator, List, Tuple, Type, Union
+from typing import Collection, Iterator, List, Optional, Tuple, Type, Union
 
 from platformdirs import user_cache_dir
 
@@ -143,7 +143,7 @@ class SQLiteCache(BaseCache):
         self,
         key: str = 'expires',
         reversed: bool = False,
-        limit: int = None,
+        limit: Optional[int] = None,
         expired: bool = True,
     ) -> Iterator[CachedResponse]:
         """Get cached responses, with sorting and other query options.
@@ -334,7 +334,11 @@ class SQLiteDict(BaseStorage):
             return page_count * page_size
 
     def sorted(
-        self, key: str = 'expires', reversed: bool = False, limit: int = None, expired: bool = True
+        self,
+        key: str = 'expires',
+        reversed: bool = False,
+        limit: Optional[int] = None,
+        expired: bool = True,
     ) -> Iterator[CachedResponse]:
         """Get cache values in sorted order; see :py:meth:`.SQLiteCache.sorted` for usage details"""
         # Get sort key, direction, and limit
@@ -420,9 +424,9 @@ def get_cache_path(db_path: AnyPath, use_cache_dir: bool = False, use_temp: bool
 def sqlite_template(
     timeout: float = 5.0,
     detect_types: int = 0,
-    isolation_level: str = None,
+    isolation_level: Optional[str] = None,
     check_same_thread: bool = True,
-    factory: Type = None,
+    factory: Optional[Type] = None,
     cached_statements: int = 100,
     uri: bool = False,
 ):
diff --git a/requests_cache/models/raw_response.py b/requests_cache/models/raw_response.py
index dfc5591..f95afab 100644
--- a/requests_cache/models/raw_response.py
+++ b/requests_cache/models/raw_response.py
@@ -1,6 +1,6 @@
 from io import BytesIO
 from logging import getLogger
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 from attr import define, field, fields_dict
 from requests import Response
@@ -37,7 +37,7 @@ class CachedHTTPResponse(RichMixin, HTTPResponse):
     strict: int = field(default=0)
     version: int = field(default=0)
 
-    def __init__(self, body: bytes = None, **kwargs):
+    def __init__(self, body: Optional[bytes] = None, **kwargs):
         """First initialize via HTTPResponse, then via attrs"""
         kwargs = {k: v for k, v in kwargs.items() if v is not None}
         super().__init__(body=BytesIO(body or b''), preload_content=False, **kwargs)
@@ -45,7 +45,7 @@ class CachedHTTPResponse(RichMixin, HTTPResponse):
         self.__attrs_init__(**kwargs)  # type: ignore # False positive in mypy 0.920+?
 
     @classmethod
-    def from_response(cls, response: Response):
+    def from_response(cls, response: Response) -> 'CachedHTTPResponse':
         """Create a CachedHTTPResponse based on an original response"""
         # Copy basic attributes
         raw = response.raw
@@ -94,7 +94,7 @@ class CachedHTTPResponse(RichMixin, HTTPResponse):
             self._fp.close()
         return data
 
-    def reset(self, body: bytes = None):
+    def reset(self, body: Optional[bytes] = None):
         """Reset raw response file pointer, and optionally update content"""
         if body is not None:
             self._body = body
diff --git a/requests_cache/models/response.py b/requests_cache/models/response.py
index e704f03..2cd6047 100755
--- a/requests_cache/models/response.py
+++ b/requests_cache/models/response.py
@@ -11,7 +11,7 @@ from requests import PreparedRequest, Response
 from requests.cookies import RequestsCookieJar
 from requests.structures import CaseInsensitiveDict
 
-from ..policy.expiration import ExpirationTime, get_expiration_datetime
+from ..policy import ExpirationTime, get_expiration_datetime
 from . import CachedHTTPResponse, CachedRequest, RichMixin
 
 if TYPE_CHECKING:
@@ -47,7 +47,7 @@ class OriginalResponse(BaseResponse):
     """Wrapper class for non-cached responses returned by :py:class:`.CachedSession`"""
 
     @classmethod
-    def wrap_response(cls, response: Response, actions: 'CacheActions'):
+    def wrap_response(cls, response: Response, actions: 'CacheActions') -> 'OriginalResponse':
         """Modify a response object in-place and add extra cache-related attributes"""
         if not isinstance(response, cls):
             response.__class__ = cls
@@ -55,7 +55,7 @@ class OriginalResponse(BaseResponse):
             response.expires = None if actions.skip_write else actions.expires  # type: ignore
             response.cache_key = None if actions.skip_write else actions.cache_key  # type: ignore
             response.created_at = datetime.utcnow()  # type: ignore
-        return response
+        return response  # type: ignore
 
 
 @define(auto_attribs=False, repr=False, slots=False)
@@ -85,7 +85,7 @@ class CachedResponse(RichMixin, BaseResponse):
         self.raw = self.raw or CachedHTTPResponse.from_cached_response(self)
 
     @classmethod
-    def from_response(cls, response: Response, **kwargs):
+    def from_response(cls, response: Response, **kwargs) -> 'CachedResponse':
         """Create a CachedResponse based on an original Response or another CachedResponse object"""
         if isinstance(response, CachedResponse):
             obj = attr.evolve(response, **kwargs)
diff --git a/requests_cache/patcher.py b/requests_cache/patcher.py
index 137e928..406ee45 100644
--- a/requests_cache/patcher.py
+++ b/requests_cache/patcher.py
@@ -22,7 +22,7 @@ logger = getLogger(__name__)
 
 def install_cache(
     cache_name: str = 'http_cache',
-    backend: BackendSpecifier = None,
+    backend: Optional[BackendSpecifier] = None,
     session_factory: Type[OriginalSession] = CachedSession,
     **kwargs,
 ):
diff --git a/requests_cache/policy/actions.py b/requests_cache/policy/actions.py
index bc59c13..50960cb 100644
--- a/requests_cache/policy/actions.py
+++ b/requests_cache/policy/actions.py
@@ -14,11 +14,12 @@ from . import (
     NEVER_EXPIRE,
     CacheDirectives,
     ExpirationTime,
+    KeyCallback,
     get_expiration_datetime,
     get_expiration_seconds,
     get_url_expiration,
 )
-from .settings import CacheSettings, KeyCallback
+from .settings import CacheSettings
 
 if TYPE_CHECKING:
     from ..models import CachedResponse
@@ -71,7 +72,9 @@ class CacheActions(RichMixin):
     _validation_headers: Dict[str, str] = field(factory=dict, repr=False)
 
     @classmethod
-    def from_request(cls, cache_key: str, request: PreparedRequest, settings: CacheSettings = None):
+    def from_request(
+        cls, cache_key: str, request: PreparedRequest, settings: Optional[CacheSettings] = None
+    ):
         """Initialize from request info and cache settings.
 
         Note on refreshing: `must-revalidate` isn't a standard request header, but is used here to
@@ -133,7 +136,7 @@ class CacheActions(RichMixin):
         """
         return get_expiration_datetime(self.expire_after)
 
-    def is_usable(self, cached_response: 'CachedResponse', error: bool = False):
+    def is_usable(self, cached_response: Optional['CachedResponse'], error: bool = False):
         """Determine whether a given cached response is "fresh enough" to satisfy the request,
         based on:
 
@@ -163,7 +166,10 @@ class CacheActions(RichMixin):
         return datetime.utcnow() < cached_response.expires + offset
 
     def update_from_cached_response(
-        self, cached_response: 'CachedResponse', create_key: KeyCallback = None, **key_kwargs
+        self,
+        cached_response: Optional['CachedResponse'],
+        create_key: Optional[KeyCallback] = None,
+        **key_kwargs,
     ):
         """Determine if we can reuse a cached response, or set headers for a conditional request
         if possible.
diff --git a/requests_cache/policy/expiration.py b/requests_cache/policy/expiration.py
index 256ab91..18a2593 100644
--- a/requests_cache/policy/expiration.py
+++ b/requests_cache/policy/expiration.py
@@ -18,7 +18,9 @@ logger = getLogger(__name__)
 
 
 def get_expiration_datetime(
-    expire_after: ExpirationTime, start_time: datetime = None, negative_delta: bool = False
+    expire_after: ExpirationTime,
+    start_time: Optional[datetime] = None,
+    negative_delta: bool = False,
 ) -> Optional[datetime]:
     """Convert an expiration value in any supported format to an absolute datetime"""
     # Never expire (or do not cache, in which case expiration won't be used)
@@ -50,7 +52,7 @@ def get_expiration_seconds(expire_after: ExpirationTime) -> int:
 
 
 def get_url_expiration(
-    url: Optional[str], urls_expire_after: ExpirationPatterns = None
+    url: Optional[str], urls_expire_after: Optional[ExpirationPatterns] = None
 ) -> ExpirationTime:
     """Check for a matching per-URL expiration, if any"""
     if not url:
diff --git a/requests_cache/serializers/cattrs.py b/requests_cache/serializers/cattrs.py
index 13d05e6..bf45c2d 100644
--- a/requests_cache/serializers/cattrs.py
+++ b/requests_cache/serializers/cattrs.py
@@ -14,7 +14,7 @@ serialization formats.
 from datetime import datetime, timedelta
 from decimal import Decimal
 from json import JSONDecodeError
-from typing import Callable, Dict, ForwardRef, MutableMapping
+from typing import Callable, Dict, ForwardRef, MutableMapping, Optional
 
 from cattr import Converter
 from requests.cookies import RequestsCookieJar, cookiejar_from_dict
@@ -50,7 +50,10 @@ class CattrStage(Stage):
     """
 
     def __init__(
-        self, factory: Callable[..., Converter] = None, decode_content: bool = False, **kwargs
+        self,
+        factory: Optional[Callable[..., Converter]] = None,
+        decode_content: bool = False,
+        **kwargs
     ):
         self.converter = init_converter(factory, **kwargs)
         self.decode_content = decode_content
@@ -68,7 +71,7 @@ class CattrStage(Stage):
 
 
 def init_converter(
-    factory: Callable[..., Converter] = None,
+    factory: Optional[Callable[..., Converter]] = None,
     convert_datetime: bool = True,
     convert_timedelta: bool = True,
 ) -> Converter:
diff --git a/requests_cache/serializers/pipeline.py b/requests_cache/serializers/pipeline.py
index 652c8f5..320e498 100644
--- a/requests_cache/serializers/pipeline.py
+++ b/requests_cache/serializers/pipeline.py
@@ -4,7 +4,7 @@
    :classes-only:
    :nosignatures:
 """
-from typing import Any, Callable, Sequence, Union
+from typing import Any, Callable, Optional, Sequence, Union
 
 from ..models import CachedResponse
 
@@ -43,7 +43,7 @@ class SerializerPipeline:
         is_binary: Indicates whether the serialized content is binary
     """
 
-    def __init__(self, stages: Sequence, name: str = None, is_binary: bool = False):
+    def __init__(self, stages: Sequence, name: Optional[str] = None, is_binary: bool = False):
         self.is_binary = is_binary
         self.stages = stages
         self.dump_stages = [stage.dumps for stage in stages]
diff --git a/requests_cache/session.py b/requests_cache/session.py
index d94adf8..c0e2563 100644
--- a/requests_cache/session.py
+++ b/requests_cache/session.py
@@ -44,18 +44,18 @@ class CacheMixin(MIXIN_BASE):
     def __init__(
         self,
         cache_name: str = DEFAULT_CACHE_NAME,
-        backend: BackendSpecifier = None,
-        serializer: SerializerType = None,
+        backend: Optional[BackendSpecifier] = None,
+        serializer: Optional[SerializerType] = None,
         expire_after: ExpirationTime = -1,
-        urls_expire_after: ExpirationPatterns = None,
+        urls_expire_after: Optional[ExpirationPatterns] = None,
         cache_control: bool = False,
         allowable_codes: Iterable[int] = DEFAULT_STATUS_CODES,
         allowable_methods: Iterable[str] = DEFAULT_METHODS,
         always_revalidate: bool = False,
         ignored_parameters: Iterable[str] = DEFAULT_IGNORED_PARAMS,
         match_headers: Union[Iterable[str], bool] = False,
-        filter_fn: FilterCallback = None,
-        key_fn: KeyCallback = None,
+        filter_fn: Optional[FilterCallback] = None,
+        key_fn: Optional[KeyCallback] = None,
         stale_if_error: Union[bool, int] = False,
         **kwargs,
     ):
@@ -127,7 +127,7 @@ class CacheMixin(MIXIN_BASE):
         method: str,
         url: str,
         *args,
-        headers: MutableMapping[str, str] = None,
+        headers: Optional[MutableMapping[str, str]] = None,
         expire_after: ExpirationTime = None,
         only_if_cached: bool = False,
         refresh: bool = False,
@@ -220,7 +220,7 @@ class CacheMixin(MIXIN_BASE):
         self,
         request: PreparedRequest,
         actions: CacheActions,
-        cached_response: CachedResponse = None,
+        cached_response: Optional[CachedResponse] = None,
         **kwargs,
     ) -> AnyResponse:
         """Send a request and cache the response, unless disabled by settings or headers.