1 files changed, 39 insertions, 0 deletions
diff --git a/Lib/test/test_concurrent_futures.py b/Lib/test/test_concurrent_futures.py
index c8fa35e..af77f81 100644
--- a/Lib/test/test_concurrent_futures.py
+++ b/Lib/test/test_concurrent_futures.py
@@ -342,6 +342,29 @@ class ExecutorShutdownTest:
         for f in fs:
             f.result()
 
+    def test_cancel_futures(self):
+        executor = self.executor_type(max_workers=3)
+        fs = [executor.submit(time.sleep, .1) for _ in range(50)]
+        executor.shutdown(cancel_futures=True)
+        # We can't guarantee the exact number of cancellations, but we can
+        # guarantee that *some* were cancelled. With setting max_workers to 3,
+        # most of the submitted futures should have been cancelled.
+        cancelled = [fut for fut in fs if fut.cancelled()]
+        self.assertTrue(len(cancelled) >= 35, msg=f"{len(cancelled)=}")
+
+        # Ensure the other futures were able to finish.
+        # Use "not fut.cancelled()" instead of "fut.done()" to include futures
+        # that may have been left in a pending state.
+        others = [fut for fut in fs if not fut.cancelled()]
+        for fut in others:
+            self.assertTrue(fut.done(), msg=f"{fut._state=}")
+            self.assertIsNone(fut.exception())
+
+        # Similar to the number of cancelled futures, we can't guarantee the
+        # exact number that completed. But, we can guarantee that at least
+        # one finished.
+        self.assertTrue(len(others) > 0, msg=f"{len(others)=}")
+
     def test_hang_issue39205(self):
         """shutdown(wait=False) doesn't hang at exit with running futures.
 
@@ -422,6 +445,22 @@ class ThreadPoolShutdownTest(ThreadPoolMixin, ExecutorShutdownTest, BaseTestCase
             self.assertRegex(t.name, r'ThreadPoolExecutor-\d+_[0-4]$')
             t.join()
 
+    def test_cancel_futures_wait_false(self):
+        # Can only be reliably tested for TPE, since PPE often hangs with
+        # `wait=False` (even without *cancel_futures*).
+        rc, out, err = assert_python_ok('-c', """if True:
+            from concurrent.futures import ThreadPoolExecutor
+            from test.test_concurrent_futures import sleep_and_print
+            if __name__ == "__main__":
+                t = ThreadPoolExecutor()
+                t.submit(sleep_and_print, .1, "apple")
+                t.shutdown(wait=False, cancel_futures=True)
+            """.format(executor_type=self.executor_type.__name__))
+        # Errors in atexit hooks don't change the process exit code, check
+        # stderr manually.
+        self.assertFalse(err)
+        self.assertEqual(out.strip(), b"apple")
+
 
 class ProcessPoolShutdownTest(ExecutorShutdownTest):
     def _prime_executor(self):