Simplify and Fix test_decorator.py

test/test_decorator.py

@@ -1,13 +1,11 @@
-"""Tests simple parsing decorators.
-"""
+"""Tests simple parsing decorators."""
 import collections
 import dataclasses
 import functools
-import inspect
 import sys
-import typing
 from typing import Callable
-
+import typing
+import inspect
 import pytest
 
 import simple_parsing as sp
@@ -43,7 +41,7 @@ def pop(self, index, default_value=None):
             return default_value
 
 
-def partial(fn: Callable, *args, **kwargs) -> Callable:
+def change_defaults(fn: Callable, *args, **kwargs) -> Callable:
     """Partial via changing the signature defaults."""
 
     @functools.wraps(fn)
@@ -69,29 +67,49 @@ def _wrapper(*other_args, **other_kwargs):
     return _wrapper
 
 
+def _xfail_in_py311(*param):
+    return pytest.param(
+        *param,
+        marks=pytest.mark.xfail(
+            sys.version_info >= (3, 11),
+            reason="TODO: test doesn't work in Python 3.11",
+            raises=ValueError,  # "non-default argument follows default argument"
+            strict=True,
+        ),
+    )
+
+
 @pytest.mark.parametrize(
     "args, expected, fn",
     [
-        ("", 1, partial(_fn_with_positional_only, 1)),
-        ("2", 2, partial(_fn_with_positional_only, 1)),
-        ("2", 2, _fn_with_positional_only),
-        ("", 1, partial(_fn_with_keyword_only, x=1)),
-        ("--x=2", 2, partial(_fn_with_keyword_only, x=1)),
-        ("--x=2", 2, _fn_with_keyword_only),
-        ("", 3, partial(_fn_with_all_argument_types, 1, b=1, c=1)),
-        ("2", 4, partial(_fn_with_all_argument_types, b=1, c=1)),
-        ("2 --b=2", 5, partial(_fn_with_all_argument_types, c=1)),
-        ("2 --b=2 --c=2", 6, _fn_with_all_argument_types),
-        ("--c=2", 4, partial(_fn_with_all_argument_types, 1, b=1)),
-        ("--b=2", 4, partial(_fn_with_all_argument_types, 1, c=1)),
-        ("--b=2 --c=2", 5, partial(_fn_with_all_argument_types, 1)),
+        ("", 1, change_defaults(_fn_with_positional_only, 1)),
+        ("2", 2, change_defaults(_fn_with_positional_only, 1)),
+        ("2", 2, change_defaults(_fn_with_positional_only)),
+        ("", 1, change_defaults(_fn_with_keyword_only, x=1)),
+        ("--x=2", 2, change_defaults(_fn_with_keyword_only, x=1)),
+        ("--x=2", 2, change_defaults(_fn_with_keyword_only)),
+        ("", 3, change_defaults(_fn_with_all_argument_types, 1, b=1, c=1)),
+        ("2", 4, change_defaults(_fn_with_all_argument_types, b=1, c=1)),
+        ("2 --b=2", 5, change_defaults(_fn_with_all_argument_types, c=1)),
+        ("2 --b=2 --c=2", 6, change_defaults(_fn_with_all_argument_types)),
+        ("--c=2", 4, change_defaults(_fn_with_all_argument_types, 1, b=1)),
+        _xfail_in_py311(
+            "--b=2", 4, functools.partial(change_defaults, _fn_with_all_argument_types, 1, c=1)
+        ),
+        _xfail_in_py311(
+            "--b=2 --c=2", 5, functools.partial(change_defaults, _fn_with_all_argument_types, 1)
+        ),
     ],
 )
 def test_simple_arguments(
     args: str,
     expected: int,
     fn: Callable,
 ):
+    if isinstance(fn, functools.partial):
+        # In Python 3.11.4, the inspect module had a backward-incompatible change. We need to have
+        # this additional level of indirection.
+        fn = fn()
     decorated = sp.decorators.main(fn, args=args)
     assert decorated() == expected
 
@@ -100,25 +118,16 @@ def _fn_with_nested_dataclass(x: int, /, *, data: AddThreeNumbers) -> int:
     return x + data()
 
 
-def _xfail_in_py311(*param):
-    return pytest.param(
-        *param,
-        marks=pytest.mark.xfail(
-            sys.version_info >= (3, 11),
-            reason="TODO: test doesn't work in Python 3.11",
-            strict=True,
-        ),
-    )
-
-
 @pytest.mark.parametrize(
-    "args, expected, fn",
+    ("args", "expected", "fn"),
     [
-        _xfail_in_py311("", 1, partial(_fn_with_nested_dataclass, 1, data=AddThreeNumbers())),
-        ("--a=1", 2, partial(_fn_with_nested_dataclass, 1)),
-        ("--a=1 --b=1", 3, partial(_fn_with_nested_dataclass, 1)),
-        ("--a=1 --b=1 --c=1", 4, partial(_fn_with_nested_dataclass, 1)),
-        ("2 --a=1 --b=1 --c=1", 5, partial(_fn_with_nested_dataclass)),
+        _xfail_in_py311(
+            "", 1, change_defaults(_fn_with_nested_dataclass, 1, data=AddThreeNumbers())
+        ),
+        ("--a=1", 2, change_defaults(_fn_with_nested_dataclass, 1)),
+        ("--a=1 --b=1", 3, change_defaults(_fn_with_nested_dataclass, 1)),
+        ("--a=1 --b=1 --c=1", 4, change_defaults(_fn_with_nested_dataclass, 1)),
+        ("2 --a=1 --b=1 --c=1", 5, change_defaults(_fn_with_nested_dataclass)),
     ],
 )
 def test_nested_dataclass(