bpo-45678: Add functools.singledispatchmethod tests (pythonGH-29328)

(cherry picked from commit 5a14929) Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

Author: AlexWaygood

Lib/test/test_functools.py

@@ -2411,14 +2411,18 @@ def _(cls, arg):
  self.assertEqual(A.t(0.0).arg, "base")
 
  def test_abstractmethod_register(self):
- class Abstract(abc.ABCMeta):
+ class Abstract(metaclass=abc.ABCMeta):
 
  @functools.singledispatchmethod
  @abc.abstractmethod
  def add(self, x, y):
  pass
 
  self.assertTrue(Abstract.add.__isabstractmethod__)
+ self.assertTrue(Abstract.__dict__['add'].__isabstractmethod__)
+
+ with self.assertRaises(TypeError):
+ Abstract()
 
  def test_type_ann_register(self):
  class A:
@@ -2479,6 +2483,42 @@ def _(cls, arg: str):
  self.assertEqual(A.t('').arg, "str")
  self.assertEqual(A.t(0.0).arg, "base")
 
+ def test_method_wrapping_attributes(self):
+ class A:
+ @functools.singledispatchmethod
+ def func(self, arg: int) -> str:
+ """My function docstring"""
+ return str(arg)
+ @functools.singledispatchmethod
+ @classmethod
+ def cls_func(cls, arg: int) -> str:
+ """My function docstring"""
+ return str(arg)
+ @functools.singledispatchmethod
+ @staticmethod
+ def static_func(arg: int) -> str:
+ """My function docstring"""
+ return str(arg)
+
+ for meth in (
+ A.func,
+ A().func,
+ A.cls_func,
+ A().cls_func,
+ A.static_func,
+ A().static_func
+ ):
+ with self.subTest(meth=meth):
+ self.assertEqual(meth.__doc__, 'My function docstring')
+ self.assertEqual(meth.__annotations__['arg'], int)
+
+ self.assertEqual(A.func.__name__, 'func')
+ self.assertEqual(A().func.__name__, 'func')
+ self.assertEqual(A.cls_func.__name__, 'cls_func')
+ self.assertEqual(A().cls_func.__name__, 'cls_func')
+ self.assertEqual(A.static_func.__name__, 'static_func')
+ self.assertEqual(A().static_func.__name__, 'static_func')
+
  def test_invalid_registrations(self):
  msg_prefix = "Invalid first argument to `register()`: "
  msg_suffix = (

Misc/NEWS.d/next/Tests/2021-10-30-13-12-20.bpo-45678.bKrYeS.rst

@@ -0,0 +1,2 @@
+Add tests to ensure that ``functools.singledispatchmethod`` correctly wraps
+the attributes of the target function.