From 376ffc6ac491da74920aed1b8e35bc371cb766ac Mon Sep 17 00:00:00 2001
From: Iurii Kemaev <6885137+hbq1@users.noreply.github.com>
Date: Tue, 6 Apr 2021 06:14:01 +0100
Subject: bpo-43176: Fix processing of empty dataclasses (GH-24484)

When a dataclass inherits from an empty base, all immutability checks are omitted. This PR fixes this and adds tests for it.

Automerge-Triggered-By: GH:ericvsmith
---
 Lib/test/test_dataclasses.py | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

(limited to 'Lib/test/test_dataclasses.py')

diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index 5515ca4940..12c1918602 100644
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -2594,6 +2594,30 @@ class TestFrozen(unittest.TestCase):
         self.assertEqual(d.i, 0)
         self.assertEqual(d.j, 10)
 
+    def test_inherit_nonfrozen_from_empty_frozen(self):
+        @dataclass(frozen=True)
+        class C:
+            pass
+
+        with self.assertRaisesRegex(TypeError,
+                                    'cannot inherit non-frozen dataclass from a frozen one'):
+            @dataclass
+            class D(C):
+                j: int
+
+    def test_inherit_nonfrozen_from_empty(self):
+        @dataclass
+        class C:
+            pass
+
+        @dataclass
+        class D(C):
+            j: int
+
+        d = D(3)
+        self.assertEqual(d.j, 3)
+        self.assertIsInstance(d, C)
+
     # Test both ways: with an intermediate normal (non-dataclass)
     #  class and without an intermediate class.
     def test_inherit_nonfrozen_from_frozen(self):
-- 
cgit v1.2.1