Python 3.13 support

.github/workflows/main.yml

@@ -14,7 +14,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "pypy-3.10"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "pypy-3.10"]
       fail-fast: false
 
     steps:

HISTORY.md

@@ -18,6 +18,8 @@ Our backwards-compatibility policy can be found [here](https://github.com/python
   ([#577](https://github.com/python-attrs/cattrs/pull/577))
 - Add a [Migrations](https://catt.rs/latest/migrations.html) page, with instructions on migrating changed behavior for each version.
   ([#577](https://github.com/python-attrs/cattrs/pull/577))
+- Python 3.13 is now supported.
+  ([#543](https://github.com/python-attrs/cattrs/pull/543) [#547](https://github.com/python-attrs/cattrs/issues/547))
 
 ## 24.1.2 (2024-09-22)
 

pyproject.toml

@@ -43,7 +43,7 @@ authors = [
 ]
 dependencies = [
     "attrs>=23.1.0",
-    "typing-extensions>=4.1.0, !=4.6.3; python_version < '3.11'",
+    "typing-extensions>=4.12.2",
     "exceptiongroup>=1.1.1; python_version < '3.11'",
 ]
 requires-python = ">=3.8"
@@ -59,6 +59,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
     "Typing :: Typed",
@@ -77,7 +78,7 @@ ujson = [
     "ujson>=5.10.0",
 ]
 orjson = [
-    "orjson>=3.9.2; implementation_name == \"cpython\"",
+    "orjson>=3.10.7; implementation_name == \"cpython\"",
 ]
 msgpack = [
     "msgpack>=1.0.5",

src/cattrs/dispatch.py

@@ -91,9 +91,9 @@ class MultiStrategyDispatch(Generic[Hook]):
     MultiStrategyDispatch uses a combination of exact-match dispatch,
     singledispatch, and FunctionDispatch.
 
-    :param converter: A converter to be used for factories that require converters.
     :param fallback_factory: A hook factory to be called when a hook cannot be
         produced.
+    :param converter: A converter to be used for factories that require converters.
 
     .. versionchanged:: 23.2.0
         Fallbacks are now factories.
@@ -103,7 +103,6 @@ class MultiStrategyDispatch(Generic[Hook]):
     """
 
     _fallback_factory: HookFactory[Hook]
-    _converter: BaseConverter
     _direct_dispatch: dict[TargetType, Hook]
     _function_dispatch: FunctionDispatch
     _single_dispatch: Any

src/cattrs/gen/__init__.py

@@ -14,6 +14,7 @@
 )
 
 from attrs import NOTHING, Attribute, Factory, resolve_types
+from typing_extensions import NoDefault
 
 from .._compat import (
     ANIES,
@@ -1029,6 +1030,9 @@ def iterable_unstructure_factory(
     """A hook factory for unstructuring iterables.
 
     :param unstructure_to: Force unstructuring to this type, if provided.
+
+    ..  versionchanged:: 24.2.0
+        `typing.NoDefault` is now correctly handled as `Any`.
     """
     handler = converter.unstructure
 
@@ -1039,6 +1043,8 @@ def iterable_unstructure_factory(
         type_arg = cl.__args__[0]
         if isinstance(type_arg, TypeVar):
             type_arg = getattr(type_arg, "__default__", Any)
+            if type_arg is NoDefault:
+                type_arg = Any
         handler = converter.get_unstructure_hook(type_arg, cache_result=False)
         if handler == identity:
             # Save ourselves the trouble of iterating over it all.

tests/conftest.py

@@ -37,3 +37,5 @@ def converter_cls(request):
     collect_ignore_glob.append("*_695.py")
 if platform.python_implementation() == "PyPy":
     collect_ignore_glob.append("*_cpython.py")
+if sys.version_info >= (3, 13):  # Remove when msgspec supports 3.13.
+    collect_ignore_glob.append("*test_msgspec_cpython.py")

tests/test_preconf.py

@@ -4,7 +4,7 @@
 from json import dumps as json_dumps
 from json import loads as json_loads
 from platform import python_implementation
-from typing import Any, Dict, List, NamedTuple, NewType, Tuple, Union
+from typing import Any, Dict, Final, List, NamedTuple, NewType, Tuple, Union
 
 import pytest
 from attrs import define
@@ -699,7 +699,10 @@ def test_cbor2_unions(union_and_val: tuple, detailed_validation: bool):
     assert converter.structure(val, type) == val
 
 
-@pytest.mark.skipif(python_implementation() == "PyPy", reason="no msgspec on PyPy")
+NO_MSGSPEC: Final = python_implementation() == "PyPy" or sys.version_info[:2] >= (3, 13)
+
+
+@pytest.mark.skipif(NO_MSGSPEC, reason="msgspec not available")
 @given(everythings(allow_inf=False))
 def test_msgspec_json_converter(everything: Everything):
     from cattrs.preconf.msgspec import make_converter as msgspec_make_converter
@@ -709,7 +712,7 @@ def test_msgspec_json_converter(everything: Everything):
     assert converter.loads(raw, Everything) == everything
 
 
-@pytest.mark.skipif(python_implementation() == "PyPy", reason="no msgspec on PyPy")
+@pytest.mark.skipif(NO_MSGSPEC, reason="msgspec not available")
 @given(everythings(allow_inf=False))
 def test_msgspec_json_unstruct_collection_overrides(everything: Everything):
     """Ensure collection overrides work."""
@@ -724,7 +727,7 @@ def test_msgspec_json_unstruct_collection_overrides(everything: Everything):
     assert raw["a_frozenset"] == sorted(raw["a_frozenset"])
 
 
-@pytest.mark.skipif(python_implementation() == "PyPy", reason="no msgspec on PyPy")
+@pytest.mark.skipif(NO_MSGSPEC, reason="msgspec not available")
 @given(
     union_and_val=native_unions(
         include_datetimes=False,

tox.ini

@@ -6,10 +6,12 @@ python =
     3.10: py310
     3.11: py311, docs
     3.12: py312, lint
+    3.13: py313
     pypy-3: pypy3
 
+
 [tox]
-envlist = pypy3, py38, py39, py310, py311, py312, lint, docs
+envlist = pypy3, py38, py39, py310, py311, py312, py313, lint, docs
 isolated_build = true
 skipsdist = true
 
@@ -42,6 +44,15 @@ setenv =
     COVERAGE_PROCESS_START={toxinidir}/pyproject.toml
     COVERAGE_CORE=sysmon
 
+[testenv:py313]
+setenv =
+    PDM_IGNORE_SAVED_PYTHON="1"
+    COVERAGE_PROCESS_START={toxinidir}/pyproject.toml
+    COVERAGE_CORE=sysmon
+commands_pre =
+    pdm sync -G ujson,msgpack,pyyaml,tomlkit,cbor2,bson,orjson,test
+    python -c 'import pathlib; pathlib.Path("{env_site_packages_dir}/cov.pth").write_text("import coverage; coverage.process_startup()")'
+
 [testenv:pypy3]
 setenv =
     FAST = 1