check that weak linking works for the time module

Lib/test/test_time.py

@@ -1041,6 +1041,36 @@ def test_object_to_timespec(self):
             with self.assertRaises(ValueError):
                 pytime_object_to_timespec(float('nan'), time_rnd)
 
+@unittest.skipUnless(sys.platform == "darwin", "test weak linking on macOS")
+class TestTimeWeaklinking(unittest.TestCase):
+    # These test cases verify that weak linking support on macOS works
+    # as expected. These cases only test new behaviour introduced by weak linking,
+    # regular behaviour is tested by the normal test cases.
+    def setUp(self):
+        import sysconfig
+        import platform
+
+        config_vars = sysconfig.get_config_vars()
+        self.available = { nm for nm in config_vars if nm.startswith("HAVE_") and config_vars[nm] }
+        self.mac_ver = tuple(int(part) for part in platform.mac_ver()[0].split("."))
+
+    def _verify_available(self, name):
+        if name not in self.available:
+            raise unittest.SkipTest(f"{name} not weak-linked")
+
+    def test_clock_functions(self):
+        self._verify_available("HAVE_CLOCK_GETTIME")
+        clock_names = [
+            "CLOCK_MONOTONIC", "clock_gettime", "clock_gettime_ns", "clock_settime", 
+            "clock_settime_ns", "clock_getres"]
+        if self.mac_ver >= (10, 16):
+           for name in clock_names:
+               self.assertTrue(hasattr(time, name), "time.{name} is not available")
+
+        else:
+           for name in clock_names:
+               self.assertFalse(hasattr(time, name), "time.{name} is available")
+
 
 if __name__ == "__main__":
     unittest.main()