Fix up docstring for tests (#5090)

tests/util/test_async.py

@@ -86,6 +86,7 @@ class RunCoroutineThreadsafeTests(test_utils.TestCase):
     """Test case for asyncio.run_coroutine_threadsafe."""
 
     def setUp(self):
+        """Test setup method."""
         self.loop = asyncio.new_event_loop()
         self.set_event_loop(self.loop)  # Will cleanup properly
 
@@ -126,16 +127,14 @@ class RunCoroutineThreadsafeTests(test_utils.TestCase):
         self.assertEqual(result, 3)
 
     def test_run_coroutine_threadsafe_with_exception(self):
-        """Test coroutine submission from a thread to an event loop
-        when an exception is raised."""
+        """Test coroutine submission from thread to event loop on exception."""
         future = self.loop.run_in_executor(None, self.target, True)
         with self.assertRaises(RuntimeError) as exc_context:
             self.loop.run_until_complete(future)
         self.assertIn("Fail!", exc_context.exception.args)
 
     def test_run_coroutine_threadsafe_with_timeout(self):
-        """Test coroutine submission from a thread to an event loop
-        when a timeout is raised."""
+        """Test coroutine submission from thread to event loop on timeout."""
         callback = lambda: self.target(timeout=0)  # noqa
         future = self.loop.run_in_executor(None, callback)
         with self.assertRaises(asyncio.TimeoutError):
@@ -146,8 +145,7 @@ class RunCoroutineThreadsafeTests(test_utils.TestCase):
             self.assertTrue(task.done())
 
     def test_run_coroutine_threadsafe_task_cancelled(self):
-        """Test coroutine submission from a tread to an event loop
-        when the task is cancelled."""
+        """Test coroutine submission from tread to event loop on cancel."""
         callback = lambda: self.target(cancel=True)  # noqa
         future = self.loop.run_in_executor(None, callback)
         with self.assertRaises(asyncio.CancelledError):