Added failing test

tests/test_memcache.py

@@ -1,5 +1,11 @@
 from __future__ import print_function
 
+from itertools import chain
+import multiprocessing
+import os
+import signal
+import sys
+import traceback
 import unittest
 
 import six
@@ -166,6 +172,73 @@ def test_disconnect_all_delete_multi(self):
         ret = self.mc.delete_multi({'keyhere': 'a', 'keythere': 'b'})
         self.assertEqual(ret, 1)
 
+    def test_exception_handling(self):
+        """Tests closing socket when custom exception raised"""
+        queue = multiprocessing.Queue()
+        process = multiprocessing.Process(target=worker, args=(self.mc, queue))
+        process.start()
+        if queue.get() != 'loop started':
+            raise ValueError(
+                'Expected "loop started" message from the child process'
+            )
+
+        # maximum test duration is 0.5 second
+        num_iters = 50
+        timeout = 0.01
+        for i in range(num_iters):
+            os.kill(process.pid, signal.SIGUSR1)
+            try:
+                exc = WorkerError(*queue.get(timeout=timeout))
+                raise exc
+            except six.moves.queue.Empty:
+                pass
+            if not process.is_alive():
+                break
+
+        if process.is_alive():
+            os.kill(process.pid, signal.SIGTERM)
+        process.join()
+
+
+class SignalException(Exception):
+    pass
+
+
+def sighandler(signum, frame):
+    raise SignalException()
+
+
+class WorkerError(Exception):
+    def __init__(self, exc, assert_tb, signal_tb=None):
+        super(WorkerError, self).__init__(
+            ''.join(chain(assert_tb, signal_tb or []))
+        )
+        self.cause = exc
+
+
+def worker(mc, queue):
+    signal.signal(signal.SIGUSR1, sighandler)
+
+    signal_tb = None
+    for i in range(100000):
+        if i == 0:
+            queue.put('loop started')
+        try:
+            k = str(i)
+            mc.set(k, i)
+            # This loop is just to increase chance to get previous value
+            # for clarity
+            for j in range(10):
+                mc.get(str(i-1))
+            res = mc.get(k)
+            assert res == i, 'Expected {} but was {}'.format(i, res)
+        except AssertionError as e:
+            assert_tb = traceback.format_exception(*sys.exc_info())
+            queue.put((e, assert_tb, signal_tb))
+            break
+        except SignalException as e:
+            signal_tb = traceback.format_exception(*sys.exc_info())
+
 
 if __name__ == '__main__':
     unittest.main()