gh-95051: ensure that timeouts scheduled with `asyncio.Timeout` that have already expired are deliverered promptly (GH-95109) (GH-95216)

Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
(cherry picked from commit 0c6f898005099be189ee65bcfda659f5fc13b802)

Co-authored-by: Thomas Grainger <tagrain@gmail.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/Lib/test/test_asyncio/test_timeouts.py b/Lib/test/test_asyncio/test_timeouts.py
index ef1ab0a..3a54297 100644
--- a/Lib/test/test_asyncio/test_timeouts.py
+++ b/Lib/test/test_asyncio/test_timeouts.py
@@ -106,6 +106,30 @@ class TimeoutTests(unittest.IsolatedAsyncioTestCase):
         self.assertLess(t1-t0, 2)
         self.assertTrue(t0 <= cm.when() <= t1)
 
+    async def test_timeout_zero_sleep_zero(self):
+        loop = asyncio.get_running_loop()
+        t0 = loop.time()
+        with self.assertRaises(TimeoutError):
+            async with asyncio.timeout(0) as cm:
+                await asyncio.sleep(0)
+        t1 = loop.time()
+        self.assertTrue(cm.expired())
+        # 2 sec for slow CI boxes
+        self.assertLess(t1-t0, 2)
+        self.assertTrue(t0 <= cm.when() <= t1)
+
+    async def test_timeout_in_the_past_sleep_zero(self):
+        loop = asyncio.get_running_loop()
+        t0 = loop.time()
+        with self.assertRaises(TimeoutError):
+            async with asyncio.timeout(-11) as cm:
+                await asyncio.sleep(0)
+        t1 = loop.time()
+        self.assertTrue(cm.expired())
+        # 2 sec for slow CI boxes
+        self.assertLess(t1-t0, 2)
+        self.assertTrue(t0 >= cm.when() <= t1)
+
     async def test_foreign_exception_passed(self):
         with self.assertRaises(KeyError):
             async with asyncio.timeout(0.01) as cm: