Add regression test for methodcaller

Author: eendebakpt

Lib/test/test_free_threading/test_methodcaller.py

@@ -0,0 +1,33 @@
+import unittest
+from threading import Thread
+from test.support import threading_helper
+from operator import methodcaller
+
+
+class TestMethodcaller(unittest.TestCase):
+    def test_methodcaller_threading(self):
+        number_of_threads = 10
+        size = 4_000
+
+        mc = methodcaller("append", 2)
+
+        def work(mc, l, ii):
+            for _ in range(ii):
+                mc(l)
+
+        worker_threads = []
+        lists = []
+        for ii in range(number_of_threads):
+            l = []
+            lists.append(l)
+            worker_threads.append(Thread(target=work, args=[mc, l, size]))
+        for t in worker_threads:
+            t.start()
+        for t in worker_threads:
+            t.join()
+        for l in lists:
+            assert len(l) == size
+
+
+if __name__ == "__main__":
+    unittest.main()