create cache by default in B2Api (resolves Backblaze#497)

b2sdk/_internal/session.py

@@ -73,10 +73,11 @@ def __init__(
         self.raw_api = api_config.raw_api_class(self.B2HTTP_CLASS(api_config))
         if account_info is None:
             account_info = self.SQLITE_ACCOUNT_INFO_CLASS()
-            if cache is None:
-                cache = AuthInfoCache(account_info)
         if cache is None:
-            cache = DummyCache()
+            if account_info:
+                cache = AuthInfoCache(account_info)
+            else:
+                cache = DummyCache()
 
         self.account_info = account_info
         self.cache = cache

b2sdk/v2/session.py

@@ -13,12 +13,26 @@
 from .b2http import B2Http
 
 from ._compat import _file_infos_rename
+from .._internal import api_config as _api_config
+from .._internal import cache as _cache
+from .._internal.account_info import abstract as _abstract
 
 
 # Override to use legacy B2Http
 class B2Session(v3.B2Session):
     B2HTTP_CLASS = staticmethod(B2Http)
 
+    def __init__(
+        self,
+        account_info: _abstract.AbstractAccountInfo | None = None,
+        cache: _cache.AbstractCache | None = None,
+        api_config: _api_config.B2HttpApiConfig = _api_config.DEFAULT_HTTP_API_CONFIG
+    ):
+        if account_info is not None and cache is None:
+            # preserve legacy behavior https://github.com/Backblaze/b2-sdk-python/issues/497#issuecomment-2147461352
+            cache = _cache.DummyCache()
+        super().__init__(account_info, cache, api_config)
+
     @_file_infos_rename
     def upload_file(
         self,

changelog.d/497.changed.md

@@ -0,0 +1,3 @@
+In `b2sdk.v3` the `B2Api` will always create `cache` from `AccountInfo` object, unless `cache` is provided explicitly.
+The current stable `b2sdk.v2` remains unchanged, i.e. `DummyCache` is created by default if `account_info` was provided, but not `cache`.
+Documentation for `b2sdk.v2` was updated with the new recommended usage, e.g. `B2Api(info, cache=AuthInfoCache(info))`, to achieve the same behavior as `b2sdk.v3`.

doc/source/quick_start.rst

@@ -12,7 +12,7 @@ Prepare b2sdk
 
     >>> from b2sdk.v2 import *
     >>> info = InMemoryAccountInfo()
-    >>> b2_api = B2Api(info)
+    >>> b2_api = B2Api(info, cache=AuthInfoCache(info))
     >>> application_key_id = '4a5b6c7d8e9f'
     >>> application_key = '001b8e23c26ff6efb941e237deb182b9599a84bef7'
     >>> b2_api.authorize_account("production", application_key_id, application_key)

test/unit/test_session.py

@@ -11,6 +11,8 @@
 
 from unittest import mock
 
+from apiver_deps import AuthInfoCache, B2Session, DummyCache, InMemoryAccountInfo
+
 from .account_info.fixtures import *  # noqa
 from .fixtures import *  # noqa
 
@@ -71,3 +73,16 @@ def test_clear_cache(self):
         self.b2_session.authorize_account('dev', '123', '456')
 
         assert self.b2_session.cache.clear.called is True
+
+
+def test_session__with_in_memory_account_info(apiver_int):
+    memory_info = InMemoryAccountInfo()
+    b2_session = B2Session(account_info=memory_info,)
+
+    assert b2_session.account_info is memory_info
+
+    if apiver_int < 3:
+        assert isinstance(b2_session.cache, DummyCache)
+    else:
+        assert isinstance(b2_session.cache, AuthInfoCache)
+        assert b2_session.cache.info is memory_info