gh-105331: Change asyncio.sleep to raise `ValueError for nan (#105641)

Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>
Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>

Doc/library/asyncio-task.rst

@@ -426,6 +426,9 @@ Sleeping
    .. versionchanged:: 3.10
       Removed the *loop* parameter.
 
+   .. versionchanged:: 3.13
+      Raises :exc:`ValueError` if *delay* is :data:`~math.nan`.
+
 
 Running Tasks Concurrently
 ==========================

Lib/asyncio/tasks.py

@@ -15,6 +15,7 @@ import contextvars
 import functools
 import inspect
 import itertools
+import math
 import types
 import warnings
 import weakref
@@ -646,6 +647,9 @@ async def sleep(delay, result=None):
         await __sleep0()
         return result
 
+    if math.isnan(delay):
+        raise ValueError("Invalid delay: NaN (not a number)")
+
     loop = events.get_running_loop()
     future = loop.create_future()
     h = loop.call_later(delay,

Lib/test/test_asyncio/test_tasks.py

@@ -1609,6 +1609,21 @@ class BaseTaskTests:
         self.assertEqual(t.result(), 'yeah')
         self.assertAlmostEqual(0.1, loop.time())
 
+    def test_sleep_when_delay_is_nan(self):
+
+        def gen():
+            yield
+
+        loop = self.new_test_loop(gen)
+
+        async def sleeper():
+            await asyncio.sleep(float("nan"))
+
+        t = self.new_task(loop, sleeper())
+
+        with self.assertRaises(ValueError):
+            loop.run_until_complete(t)
+
     def test_sleep_cancel(self):
 
         def gen():

Misc/NEWS.d/next/Core and Builtins/2023-06-11-09-14-30.gh-issue-105331.nlZvoW.rst

@@ -0,0 +1,2 @@
+Raise :exc:`ValueError` if the ``delay`` argument to :func:`asyncio.sleep` is a NaN (matching :func:`time.sleep`).
+