[3.11] Add more syslog tests (GH-97953). (GH-98096)

(cherry picked from commit cae7d1d7a7)

Lib/test/test_syslog.py

@@ -1,5 +1,9 @@
-from test.support import import_helper
+from test.support import import_helper, threading_helper
 syslog = import_helper.import_module("syslog") #skip if not supported
+from test import support
+import sys
+import threading
+import time
 import unittest
 
 # XXX(nnorwitz): This test sucks.  I don't know of a platform independent way
@@ -8,6 +12,9 @@ import unittest
 
 class Test(unittest.TestCase):
 
+    def tearDown(self):
+        syslog.closelog()
+
     def test_openlog(self):
         syslog.openlog('python')
         # Issue #6697.
@@ -18,22 +25,59 @@ class Test(unittest.TestCase):
         syslog.syslog('test message from python test_syslog')
         syslog.syslog(syslog.LOG_ERR, 'test error from python test_syslog')
 
+    def test_syslog_implicit_open(self):
+        syslog.closelog() # Make sure log is closed
+        syslog.syslog('test message from python test_syslog')
+        syslog.syslog(syslog.LOG_ERR, 'test error from python test_syslog')
+
     def test_closelog(self):
         syslog.openlog('python')
         syslog.closelog()
+        syslog.closelog()  # idempotent operation
 
     def test_setlogmask(self):
-        syslog.setlogmask(syslog.LOG_DEBUG)
+        mask = syslog.LOG_UPTO(syslog.LOG_WARNING)
+        oldmask = syslog.setlogmask(mask)
+        self.assertEqual(syslog.setlogmask(0), mask)
+        self.assertEqual(syslog.setlogmask(oldmask), mask)
 
     def test_log_mask(self):
-        syslog.LOG_MASK(syslog.LOG_INFO)
-
-    def test_log_upto(self):
-        syslog.LOG_UPTO(syslog.LOG_INFO)
+        mask = syslog.LOG_UPTO(syslog.LOG_WARNING)
+        self.assertTrue(mask & syslog.LOG_MASK(syslog.LOG_WARNING))
+        self.assertTrue(mask & syslog.LOG_MASK(syslog.LOG_ERR))
+        self.assertFalse(mask & syslog.LOG_MASK(syslog.LOG_INFO))
 
     def test_openlog_noargs(self):
         syslog.openlog()
         syslog.syslog('test message from python test_syslog')
 
+    @threading_helper.requires_working_threading()
+    def test_syslog_threaded(self):
+        start = threading.Event()
+        stop = False
+        def opener():
+            start.wait(10)
+            i = 1
+            while not stop:
+                syslog.openlog(f'python-test-{i}')  # new string object
+                i += 1
+        def logger():
+            start.wait(10)
+            while not stop:
+                syslog.syslog('test message from python test_syslog')
+
+        orig_si = sys.getswitchinterval()
+        support.setswitchinterval(1e-9)
+        try:
+            threads = [threading.Thread(target=opener)]
+            threads += [threading.Thread(target=logger) for k in range(10)]
+            with threading_helper.start_threads(threads):
+                start.set()
+                time.sleep(0.1)
+                stop = True
+        finally:
+            sys.setswitchinterval(orig_si)
+
+
 if __name__ == "__main__":
     unittest.main()