gh-84649: Fix unstable test_rollover_at_midnight (GH-154463)

Create the log file in a fresh directory under a name which has never
been used.  On Windows, NTFS file tunneling restored the original
creation time of a file recreated with the same name, which made the
rollover time earlier than the current time and caused an unwanted
rollover.

Also check that the rollover does not happen before the specified time.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index a7ea128d64055a1d94194f5582b978ca95a92dec..06b3aa66fc47a3151eedeef0b83cf589a9fb3316 100644 (file)
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -6704,7 +6704,14 @@ class TimedRotatingFileHandlerTest(BaseFileTest):
         self.assertTrue(found, msg=msg)
 
     def test_rollover_at_midnight(self, weekly=False):
+        # Create the log file in a fresh directory under a never used name:
+        # on Windows, NTFS file tunneling restores the original creation time
+        # of a file recreated with the same name.
         os_helper.unlink(self.fn)
+        dirname = tempfile.mkdtemp()
+        self.addCleanup(os_helper.rmtree, dirname)
+        self.fn = os.path.join(dirname, 'test_rollover.log')
+
         # Emit the first records a little after the beginning of a whole
         # second, so that their file times fall inside that second and not the
         # previous one, which would cause an unwanted rollover.
@@ -6730,7 +6737,24 @@ class TimedRotatingFileHandlerTest(BaseFileTest):
         # changed, so the rollover cannot be forced by back-dating the file.
         # Wait until the clock reaches a rollover time set one second ahead.
         rollover = int(time.time()) + 1
+        if rollover - time.time() < 0.1:
+            # Leave time to emit a record before the rollover time.
+            rollover += 1
         atTime = datetime.datetime.fromtimestamp(rollover).time()
+        rolloverDate = (datetime.datetime.fromtimestamp(rollover)
+                        - datetime.timedelta(days=7 if weekly else 1))
+        otherfn = f'{self.fn}.{rolloverDate:%Y-%m-%d}'
+
+        # A record emitted before the rollover time is not rolled over.
+        fh = logging.handlers.TimedRotatingFileHandler(
+            self.fn, encoding="utf-8", when=when, atTime=atTime)
+        fh.setFormatter(fmt)
+        r2 = logging.makeLogRecord({'msg': 'testing1 3'})
+        fh.emit(r2)
+        fh.close()
+        self.assertFalse(os.path.exists(otherfn),
+                         msg=f'{otherfn} was rolled over too early')
+
         while time.time() < rollover:
             time.sleep(rollover - time.time())
         for i in range(2):
@@ -6740,9 +6764,6 @@ class TimedRotatingFileHandlerTest(BaseFileTest):
             r2 = logging.makeLogRecord({'msg': f'testing2 {i}'})
             fh.emit(r2)
             fh.close()
-        rolloverDate = (datetime.datetime.fromtimestamp(rollover)
-                        - datetime.timedelta(days=7 if weekly else 1))
-        otherfn = f'{self.fn}.{rolloverDate:%Y-%m-%d}'
         self.assertLogFile(otherfn)
         with open(self.fn, encoding="utf-8") as f:
             for i, line in enumerate(f):