Assert that ChunkWriteTimouts are not raised

Follow up for change Ibbc89449e7878fc4215e47e3f7dfe4ae58a2d638
to add a test assertion that the ChunkWriteTimeout contexts are
exited without raising the timeout exception in
iter_bytes_from_response_part().

Change-Id: I6d323cb26779e457fb5940093a81b349b333a0af

test/unit/proxy/test_server.py

@@ -22,6 +22,7 @@ import math
 import os
 import pickle
 import sys
+import traceback
 import unittest
 from contextlib import closing, contextmanager
 from gzip import GzipFile
@@ -65,7 +66,7 @@ from swift.obj import server as object_server
 from swift.common.middleware import proxy_logging, versioned_writes
 from swift.common.middleware.acl import parse_acl, format_acl
 from swift.common.exceptions import ChunkReadTimeout, DiskFileNotExist, \
-    APIVersionError
+    APIVersionError, ChunkWriteTimeout
 from swift.common import utils, constraints
 from swift.common.ring import RingData
 from swift.common.utils import mkdirs, normalize_timestamp, NullLogger
@@ -5827,6 +5828,18 @@ class TestObjectController(unittest.TestCase):
         exp = 'HTTP/1.1 201'
         self.assertEqual(headers[:len(exp)], exp)
 
+        class WrappedTimeout(ChunkWriteTimeout):
+            def __enter__(self):
+                timeouts[self] = traceback.extract_stack()
+                return super(WrappedTimeout, self).__enter__()
+
+            def __exit__(self, typ, value, tb):
+                timeouts[self] = None
+                return super(WrappedTimeout, self).__exit__(typ, value, tb)
+
+        timeouts = {}
+        with mock.patch('swift.proxy.controllers.base.ChunkWriteTimeout',
+                        WrappedTimeout):
             with mock.patch.object(_test_servers[0], 'client_timeout', new=5):
                 # get object
                 fd.write('GET /v1/a/ec-discon/test HTTP/1.1\r\n'
@@ -5842,15 +5855,25 @@ class TestObjectController(unittest.TestCase):
                 # read most of the object, and disconnect
                 fd.read(10)
                 sock.fd._sock.close()
-            condition = \
+                self._sleep_enough(
-                lambda: _test_servers[0].logger.get_lines_for_level('warning')
+                    lambda:
-            self._sleep_enough(condition)
+                    _test_servers[0].logger.get_lines_for_level('warning'))
 
         # check for disconnect message!
         expected = ['Client disconnected on read'] * 2
         self.assertEqual(
             _test_servers[0].logger.get_lines_for_level('warning'),
             expected)
+        # check that no coro was left waiting to write
+        self.assertTrue(timeouts)  # sanity - WrappedTimeout did get called
+        missing_exits = filter(lambda tb: tb is not None, timeouts.values())
+        self.assertFalse(
+            missing_exits, 'Failed to exit all ChunkWriteTimeouts.\n' +
+            ''.join(['No exit from ChunkWriteTimeout entered at:\n' +
+                     ''.join(traceback.format_list(tb)[:-1])
+                     for tb in missing_exits]))
+        # and check that the ChunkWriteTimeouts did not raise Exceptions
+        self.assertFalse(_test_servers[0].logger.get_lines_for_level('error'))
 
     @unpatch_policies
     def test_ec_client_put_disconnect(self):