GH-115776: Embed the values array into the object, for "normal" Python objects. (GH-116115)

Lib/test/test_class.py

@@ -2,7 +2,6 @@
 
 import unittest
 
-
 testmeths = [
 
 # Binary operations
@@ -789,5 +788,81 @@ class ClassTests(unittest.TestCase):
         self.assertEqual(calls, 100)
 
 
+from _testinternalcapi import has_inline_values
+
+Py_TPFLAGS_MANAGED_DICT = (1 << 2)
+
+class Plain:
+    pass
+
+
+class WithAttrs:
+
+    def __init__(self):
+        self.a = 1
+        self.b = 2
+        self.c = 3
+        self.d = 4
+
+
+class TestInlineValues(unittest.TestCase):
+
+    def test_flags(self):
+        self.assertEqual(Plain.__flags__ & Py_TPFLAGS_MANAGED_DICT, Py_TPFLAGS_MANAGED_DICT)
+        self.assertEqual(WithAttrs.__flags__ & Py_TPFLAGS_MANAGED_DICT, Py_TPFLAGS_MANAGED_DICT)
+
+    def test_has_inline_values(self):
+        c = Plain()
+        self.assertTrue(has_inline_values(c))
+        del c.__dict__
+        self.assertFalse(has_inline_values(c))
+
+    def test_instances(self):
+        self.assertTrue(has_inline_values(Plain()))
+        self.assertTrue(has_inline_values(WithAttrs()))
+
+    def test_inspect_dict(self):
+        for cls in (Plain, WithAttrs):
+            c = cls()
+            c.__dict__
+            self.assertTrue(has_inline_values(c))
+
+    def test_update_dict(self):
+        d = { "e": 5, "f": 6 }
+        for cls in (Plain, WithAttrs):
+            c = cls()
+            c.__dict__.update(d)
+            self.assertTrue(has_inline_values(c))
+
+    @staticmethod
+    def set_100(obj):
+        for i in range(100):
+            setattr(obj, f"a{i}", i)
+
+    def check_100(self, obj):
+        for i in range(100):
+            self.assertEqual(getattr(obj, f"a{i}"), i)
+
+    def test_many_attributes(self):
+        class C: pass
+        c = C()
+        self.assertTrue(has_inline_values(c))
+        self.set_100(c)
+        self.assertFalse(has_inline_values(c))
+        self.check_100(c)
+        c = C()
+        self.assertTrue(has_inline_values(c))
+
+    def test_many_attributes_with_dict(self):
+        class C: pass
+        c = C()
+        d = c.__dict__
+        self.assertTrue(has_inline_values(c))
+        self.set_100(c)
+        self.assertFalse(has_inline_values(c))
+        self.check_100(c)
+
+
+
 if __name__ == '__main__':
     unittest.main()