(Merge 3.4) Closes #21886, #21447: Fix a race condition in asyncio when setting

the result of a Future with call_soon(). Add an helper, a private method, to
set the result only if the future was not cancelled.

2 files changed, 10 insertions, 0 deletions

diff --git a/Lib/test/test_asyncio/test_futures.py b/Lib/test/test_asyncio/test_futures.py
index 96b41d6..a6071ea 100644
--- a/Lib/test/test_asyncio/test_futures.py
+++ b/Lib/test/test_asyncio/test_futures.py
@@ -343,6 +343,12 @@ class FutureTests(test_utils.TestCase):
         message = m_log.error.call_args[0][0]
         self.assertRegex(message, re.compile(regex, re.DOTALL))
 
+    def test_set_result_unless_cancelled(self):
+        fut = asyncio.Future(loop=self.loop)
+        fut.cancel()
+        fut._set_result_unless_cancelled(2)
+        self.assertTrue(fut.cancelled())
+
 
 class FutureDoneCallbackTests(test_utils.TestCase):
 
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index 83b7e61..eaef05b 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -211,6 +211,10 @@ class TaskTests(test_utils.TestCase):
         coro = ('%s() at %s:%s'
                 % (coro_qualname, code.co_filename, code.co_firstlineno))
 
+        # test repr(CoroWrapper)
+        if coroutines._DEBUG:
+            self.assertEqual(repr(gen), '<CoroWrapper %s>' % coro)
+
         # test pending Task
         t = asyncio.Task(gen, loop=self.loop)
         t.add_done_callback(Dummy())