bpo-32960: For dataclasses, disallow inheriting frozen from non-frozen classes and vice-versa, (GH-5919) (GH-5920)
This restriction will be relaxed at a future date.
(cherry picked from commit 2fa6b9eae07e2385e2acbf2e40093a21fb3a10c4)
Co-authored-by: Eric V. Smith <ericvsmith@users.noreply.github.com>
diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index 582cb34..46d485c 100755
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -637,29 +637,6 @@
y: int
self.assertNotEqual(Point(1, 3), C(1, 3))
- def test_frozen(self):
- @dataclass(frozen=True)
- class C:
- i: int
-
- c = C(10)
- self.assertEqual(c.i, 10)
- with self.assertRaises(FrozenInstanceError):
- c.i = 5
- self.assertEqual(c.i, 10)
-
- # Check that a derived class is still frozen, even if not
- # marked so.
- @dataclass
- class D(C):
- pass
-
- d = D(20)
- self.assertEqual(d.i, 20)
- with self.assertRaises(FrozenInstanceError):
- d.i = 5
- self.assertEqual(d.i, 20)
-
def test_not_tuple(self):
# Test that some of the problems with namedtuple don't happen
# here.
@@ -2475,5 +2452,66 @@
assert False, f'unknown value for expected={expected!r}'
+class TestFrozen(unittest.TestCase):
+ def test_frozen(self):
+ @dataclass(frozen=True)
+ class C:
+ i: int
+
+ c = C(10)
+ self.assertEqual(c.i, 10)
+ with self.assertRaises(FrozenInstanceError):
+ c.i = 5
+ self.assertEqual(c.i, 10)
+
+ def test_inherit(self):
+ @dataclass(frozen=True)
+ class C:
+ i: int
+
+ @dataclass(frozen=True)
+ class D(C):
+ j: int
+
+ d = D(0, 10)
+ with self.assertRaises(FrozenInstanceError):
+ d.i = 5
+ self.assertEqual(d.i, 0)
+
+ def test_inherit_from_nonfrozen_from_frozen(self):
+ @dataclass(frozen=True)
+ class C:
+ i: int
+
+ with self.assertRaisesRegex(TypeError,
+ 'cannot inherit non-frozen dataclass from a frozen one'):
+ @dataclass
+ class D(C):
+ pass
+
+ def test_inherit_from_frozen_from_nonfrozen(self):
+ @dataclass
+ class C:
+ i: int
+
+ with self.assertRaisesRegex(TypeError,
+ 'cannot inherit frozen dataclass from a non-frozen one'):
+ @dataclass(frozen=True)
+ class D(C):
+ pass
+
+ def test_inherit_from_normal_class(self):
+ class C:
+ pass
+
+ @dataclass(frozen=True)
+ class D(C):
+ i: int
+
+ d = D(10)
+ with self.assertRaises(FrozenInstanceError):
+ d.i = 5
+
+
if __name__ == '__main__':
unittest.main()