MERGE: Closes #15469: Correct __sizeof__ support for deque

1 files changed, 16 insertions, 0 deletions

diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index 24125cdd25..a8487d2d95 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -7,6 +7,7 @@ import copy
 import pickle
 from io import StringIO
 import random
+import struct
 
 BIG = 100000
 
@@ -531,6 +532,21 @@ class TestBasic(unittest.TestCase):
             gc.collect()
             self.assertTrue(ref() is None, "Cycle was not collected")
 
+    check_sizeof = support.check_sizeof
+
+    @support.cpython_only
+    def test_sizeof(self):
+        BLOCKLEN = 62
+        basesize = support.calcobjsize('2P4nlP')
+        blocksize = struct.calcsize('2P%dP' % BLOCKLEN)
+        self.assertEqual(object.__sizeof__(deque()), basesize)
+        check = self.check_sizeof
+        check(deque(), basesize + blocksize)
+        check(deque('a'), basesize + blocksize)
+        check(deque('a' * (BLOCKLEN // 2)), basesize + blocksize)
+        check(deque('a' * (BLOCKLEN // 2 + 1)), basesize + 2 * blocksize)
+        check(deque('a' * (42 * BLOCKLEN)), basesize + 43 * blocksize)
+
 class TestVariousIteratorArgs(unittest.TestCase):
 
     def test_constructor(self):