gh-100522 Test futures.as_completed timing out with a nonzero timeout value

Author: JosephSBoyle

Lib/test/test_concurrent_futures.py

@@ -711,7 +711,6 @@ def future_func():
 
 
 class AsCompletedTests:
-    # TODO([email protected]): 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)
@@ -747,6 +746,28 @@ def test_zero_timeout(self):
                               SUCCESSFUL_FUTURE]),
                          completed_futures)
 
+    def test_nonzero_timeout(self):
+        """Test ``futures.as_completed`` timing out before
+        completing it's final future completes."""
+
+        future1 = self.executor.submit(time.sleep, 1)
+        completed_futures = set()
+        try:
+            for future in futures.as_completed(
+                    [CANCELLED_AND_NOTIFIED_FUTURE,
+                     EXCEPTION_FUTURE,
+                     SUCCESSFUL_FUTURE,
+                     future1],
+                    timeout=0.01):
+                completed_futures.add(future)
+        except futures.TimeoutError:
+            pass
+
+        self.assertEqual(set([CANCELLED_AND_NOTIFIED_FUTURE,
+                              EXCEPTION_FUTURE,
+                              SUCCESSFUL_FUTURE]),
+                         completed_futures)
+
     def test_duplicate_futures(self):
         # Issue 20367. Duplicate futures should not raise exceptions or give
         # duplicate responses.