diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py index 7c917707d02f0b..c059726e9327e8 100644 --- a/Lib/test/test_dataclasses/__init__.py +++ b/Lib/test/test_dataclasses/__init__.py @@ -1317,6 +1317,29 @@ def __post_init__(self, init_base, init_derived): c = C(10, 11, 50, 51) self.assertEqual(vars(c), {'x': 21, 'y': 101}) + def test_init_var_name_shadowing(self): + # Because dataclasses rely exclusively on `__annotations__` for + # handling InitVar and `__annotations__` preserves shadowed definitions, + # you can actually shadow an InitVar with a method or property. + # + # This only works when there is no default value; `dataclasses` uses the + # actual name (which will be bound to the shadowing method) for default + # values. + @dataclass + class C: + shadowed: InitVar[int] + _shadowed: int = field(init=False) + + def __post_init__(self, shadowed): + self._shadowed = shadowed * 2 + + @property + def shadowed(self): + return self._shadowed * 3 + + c = C(5) + self.assertEqual(c.shadowed, 30) + def test_default_factory(self): # Test a factory that returns a new list. @dataclass