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Merged
kumaraditya303 merged 18 commits into from
Dec 15, 2025
Merged

gh-142651: Make call_count of Mock thread safe #142656

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a401818
Make call_count of Mock thread safe
chaope Dec 13, 2025
d532d23
📜🤖 Added by blurb_it.
blurb-it[bot] Dec 13, 2025
fe7be86
update doc
chaope Dec 13, 2025
29578a9
calculate call_count after append call_args_list
chaope Dec 13, 2025
c2e4ca7
revert change on documentation for call_count.
chaope Dec 13, 2025
e9e6dfa
revert unnecessary change.
chaope Dec 13, 2025
3a4b590
revert blank line deletion
chaope Dec 13, 2025
70e9107
added TestThreadingMockRaceCondition
chaope Dec 13, 2025
dc0d804
Update Misc/NEWS.d/next/Library/2025-12-13-06-17-44.gh-issue-142651.Z…
chaope Dec 13, 2025
f05407e
Update Lib/test/test_unittest/testmock/testthreadingmock.py
chaope Dec 13, 2025
3a81b0d
update test
chaope Dec 13, 2025
23825f4
Merge branch 'fix-issue-142651' of https://github.com/chaope/cpython …
chaope Dec 13, 2025
a76318e
move self._executor.shutdown to addCleanup
chaope Dec 13, 2025
8e2348c
use 3k loops
chaope Dec 13, 2025
e7dcc57
add @requires_resource('cpu')
chaope Dec 13, 2025
851f698
update test according to comments
chaope Dec 13, 2025
3b29867
update according to comments
chaope Dec 13, 2025
16232b8
use threading_helper.start_threads
chaope Dec 14, 2025
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24 changes: 23 additions & 1 deletion Lib/test/test_unittest/testmock/testthreadingmock.py
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Original file line numberDiff line numberDiff line change
@@ -1,8 +1,10 @@
import sys
import time
import unittest
import threading
import concurrent.futures

from test.support import threading_helper
from test.support import setswitchinterval, threading_helper
from unittest.mock import patch, ThreadingMock


Expand DownExpand Up@@ -196,6 +198,26 @@ def test_reset_mock_resets_wait(self):
m.wait_until_any_call_with()
m.assert_called_once()

def test_call_count_thread_safe(self):
# See https://github.com/python/cpython/issues/142651.
m = ThreadingMock()
LOOPS = 100
THREADS = 10
def test_function():
for _ in range(LOOPS):
m()

oldswitchinterval = sys.getswitchinterval()
setswitchinterval(1e-6)
try:
threads = [threading.Thread(target=test_function) for _ in range(THREADS)]
with threading_helper.start_threads(threads):
pass
finally:
sys.setswitchinterval(oldswitchinterval)

self.assertEqual(m.call_count, LOOPS * THREADS)


if __name__ == "__main__":
unittest.main()
2 changes: 1 addition & 1 deletion Lib/unittest/mock.py
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Expand Up@@ -1180,14 +1180,14 @@ def _mock_call(self, /, *args, **kwargs):

def _increment_mock_call(self, /, *args, **kwargs):
self.called = True
self.call_count += 1

# handle call_args
# needs to be set here so assertions on call arguments pass before
# execution in the case of awaited calls
_call = _Call((args, kwargs), two=True)
self.call_args = _call
self.call_args_list.append(_call)
self.call_count = len(self.call_args_list)

# initial stuff for method_calls:
do_method_calls = self._mock_parent is not None
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2025-12-13-06-17-44.gh-issue-142651.ZRtBu4.rst
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@@ -0,0 +1,3 @@
:mod:`unittest.mock`: fix a thread safety issue where :attr:`Mock.call_count
<unittest.mock.Mock.call_count>` may return inaccurate values when the mock
is called concurrently from multiple threads.
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