bpo-28668: test.support.requires_multiprocessing_queue is removed (GH-4560)

Skip tests with test.support.import_module('multiprocessing.synchronize')
instead when the semaphore implementation is broken or missing.

Author: xdegaye

Lib/test/support/__init__.py

@@ -87,8 +87,7 @@
     "bigmemtest", "bigaddrspacetest", "cpython_only", "get_attribute",
     "requires_IEEE_754", "skip_unless_xattr", "requires_zlib",
     "anticipate_failure", "load_package_tests", "detect_api_mismatch",
-    "check__all__", "requires_multiprocessing_queue",
-    "skip_unless_bind_unix_socket",
+    "check__all__", "skip_unless_bind_unix_socket",
     # sys
     "is_jython", "is_android", "check_impl_detail", "unix_shell",
     "setswitchinterval",
@@ -1791,22 +1790,6 @@ def impl_detail(msg=None, **guards):
         msg = msg.format(' or '.join(guardnames))
     return unittest.skip(msg)
 
-_have_mp_queue = None
-def requires_multiprocessing_queue(test):
-    """Skip decorator for tests that use multiprocessing.Queue."""
-    global _have_mp_queue
-    if _have_mp_queue is None:
-        import multiprocessing
-        # Without a functioning shared semaphore implementation attempts to
-        # instantiate a Queue will result in an ImportError (issue #3770).
-        try:
-            multiprocessing.Queue()
-            _have_mp_queue = True
-        except ImportError:
-            _have_mp_queue = False
-    msg = "requires a functioning shared semaphore implementation"
-    return test if _have_mp_queue else unittest.skip(msg)(test)
-
 def _parse_guards(guards):
     # Returns a tuple ({platform_name: run_me}, default_value)
     if not guards:

Lib/test/test_logging.py

@@ -3211,9 +3211,11 @@ def test_handle_called_with_queue_queue(self, mock_handle):
             self.assertEqual(mock_handle.call_count, 5 * self.repeat,
                              'correct number of handled log messages')
 
-        @support.requires_multiprocessing_queue
         @patch.object(logging.handlers.QueueListener, 'handle')
         def test_handle_called_with_mp_queue(self, mock_handle):
+            # Issue 28668: The multiprocessing (mp) module is not functional
+            # when the mp.synchronize module cannot be imported.
+            support.import_module('multiprocessing.synchronize')
             for i in range(self.repeat):
                 log_queue = multiprocessing.Queue()
                 self.setup_and_log(log_queue, '%s_%s' % (self.id(), i))
@@ -3230,14 +3232,16 @@ def get_all_from_queue(log_queue):
             except queue.Empty:
                 return []
 
-        @support.requires_multiprocessing_queue
         def test_no_messages_in_queue_after_stop(self):
             """
             Five messages are logged then the QueueListener is stopped. This
             test then gets everything off the queue. Failure of this test
             indicates that messages were not registered on the queue until
             _after_ the QueueListener stopped.
             """
+            # Issue 28668: The multiprocessing (mp) module is not functional
+            # when the mp.synchronize module cannot be imported.
+            support.import_module('multiprocessing.synchronize')
             for i in range(self.repeat):
                 queue = multiprocessing.Queue()
                 self.setup_and_log(queue, '%s_%s' %(self.id(), i))

Misc/NEWS.d/next/Tests/2017-11-25-14-53-29.bpo-28668.Y1G6pA.rst

@@ -0,0 +1,3 @@
+test.support.requires_multiprocessing_queue is removed. Skip tests with
+test.support.import_module('multiprocessing.synchronize') instead when the
+semaphore implementation is broken or missing.