Make call_count of Mock thread safe

Author: chaope

Lib/test/test_unittest/testmock/testthreadingmock.py

@@ -1,5 +1,6 @@
 import time
 import unittest
+import threading
 import concurrent.futures
 
 from test.support import threading_helper
@@ -196,6 +197,27 @@ def test_reset_mock_resets_wait(self):
         m.wait_until_any_call_with()
         m.assert_called_once()
 
+    def test_call_count_thread_safe(self):
+        
+        m = ThreadingMock()
+        
+        # 3k loops reliably reproduces the issue while keeping runtime ~0.6s
+        LOOPS = 3_000
+        THREADS = 10
+        
+        def test_function():
+            for _ in range(LOOPS):
+                m()
+        
+        threads = [threading.Thread(target=test_function) for _ in range(THREADS)]
+        for thread in threads:
+            thread.start()
+        for thread in threads:
+            thread.join()
+        
+        self.assertEqual(m.call_count, LOOPS * THREADS,
+                        f"Expected {LOOPS * THREADS}, got {m.call_count}")
+
 
 if __name__ == "__main__":
     unittest.main()

Lib/unittest/mock.py

@@ -256,7 +256,6 @@ def reset_mock():
             ret.reset_mock()
 
     funcopy.called = False
-    funcopy.call_count = 0
     funcopy.call_args = None
     funcopy.call_args_list = _CallList()
     funcopy.method_calls = _CallList()
@@ -490,7 +489,6 @@ def __init__(
 
         __dict__['_mock_called'] = False
         __dict__['_mock_call_args'] = None
-        __dict__['_mock_call_count'] = 0
         __dict__['_mock_call_args_list'] = _CallList()
         __dict__['_mock_mock_calls'] = _CallList()
 
@@ -606,11 +604,17 @@ def __class__(self):
         return self._spec_class
 
     called = _delegating_property('called')
-    call_count = _delegating_property('call_count')
     call_args = _delegating_property('call_args')
     call_args_list = _delegating_property('call_args_list')
     mock_calls = _delegating_property('mock_calls')
 
+    @property
+    def call_count(self):
+        sig = self._mock_delegate
+        if sig is None:
+            return len(self._mock_call_args_list)
+        return len(sig.call_args_list)
+
 
     def __get_side_effect(self):
         delegated = self._mock_delegate
@@ -646,7 +650,6 @@ def reset_mock(self, visited=None, *,
 
         self.called = False
         self.call_args = None
-        self.call_count = 0
         self.mock_calls = _CallList()
         self.call_args_list = _CallList()
         self.method_calls = _CallList()
@@ -1180,7 +1183,6 @@ 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