[Python-checkins] gh-100522 Add a test for 'futures.as_completed' timing out with a non-zero timeout value (#100523)

[gpshead]

https://github.com/python/cpython/commit/a2262789abccb68a61bb4047743fbcbd9a64b13c
commit: a2262789abccb68a61bb4047743fbcbd9a64b13c
branch: main
author: JosephSBoyle <48555120+JosephSBoyle at users.noreply.github.com>
committer: gpshead <greg at krypto.org>
date: 2023-01-25T23:01:11-08:00
summary:

gh-100522 Add a test for 'futures.as_completed' timing out with a non-zero timeout value (#100523)

files:
M Lib/test/test_concurrent_futures.py

diff --git a/Lib/test/test_concurrent_futures.py b/Lib/test/test_concurrent_futures.py
index fe9fdc4f44d3..b3520ae3994e 100644
--- a/Lib/test/test_concurrent_futures.py
+++ b/Lib/test/test_concurrent_futures.py
@@ -711,7 +711,6 @@ def future_func():
 
 
 class AsCompletedTests:
-    # TODO(brian at sweetapp.com): Should have a test with a non-zero timeout.
     def test_no_timeout(self):
         future1 = self.executor.submit(mul, 2, 21)
         future2 = self.executor.submit(mul, 7, 6)
@@ -728,24 +727,29 @@ def test_no_timeout(self):
                  future1, future2]),
                 completed)
 
-    def test_zero_timeout(self):
-        future1 = self.executor.submit(time.sleep, 2)
-        completed_futures = set()
-        try:
-            for future in futures.as_completed(
-                    [CANCELLED_AND_NOTIFIED_FUTURE,
-                     EXCEPTION_FUTURE,
-                     SUCCESSFUL_FUTURE,
-                     future1],
-                    timeout=0):
-                completed_futures.add(future)
-        except futures.TimeoutError:
-            pass
+    def test_future_times_out(self):
+        """Test ``futures.as_completed`` timing out before
+        completing it's final future."""
+        already_completed = {CANCELLED_AND_NOTIFIED_FUTURE,
+                             EXCEPTION_FUTURE,
+                             SUCCESSFUL_FUTURE}
 
-        self.assertEqual(set([CANCELLED_AND_NOTIFIED_FUTURE,
-                              EXCEPTION_FUTURE,
-                              SUCCESSFUL_FUTURE]),
-                         completed_futures)
+        for timeout in (0, 0.01):
+            with self.subTest(timeout):
+
+                future = self.executor.submit(time.sleep, 0.1)
+                completed_futures = set()
+                try:
+                    for f in futures.as_completed(
+                        already_completed | {future},
+                        timeout
+                    ):
+                        completed_futures.add(f)
+                except futures.TimeoutError:
+                    pass
+
+                # Check that ``future`` wasn't completed.
+                self.assertEqual(completed_futures, already_completed)
 
     def test_duplicate_futures(self):
         # Issue 20367. Duplicate futures should not raise exceptions or give