Datetime test coverage (#7544)

* Added a test case for strftime("%z").

The added test checks a case with UTC offest expressed in an integer
number of seconds.

* Added a test comparing naive and aware datetimes.

Check that a greater than  comparison of a naive  datetime instance with
an aware one raises a TypeError.

* Test datetime in fold or in gap comparison both ways.

Lib/test/datetimetester.py

@@ -2345,9 +2345,10 @@ class TestDateTime(TestDate):
         t = self.theclass(2004, 12, 31, 6, 22, 33, 47)
         self.assertEqual(t.strftime("%m %d %y %f %S %M %H %j"),
                                     "12 31 04 000047 33 22 06 366")
-        tz = timezone(-timedelta(hours=2, seconds=33, microseconds=123))
-        t = t.replace(tzinfo=tz)
-        self.assertEqual(t.strftime("%z"), "-020033.000123")
+        for (s, us), z in [((33, 123), "33.000123"), ((33, 0), "33"),]:
+            tz = timezone(-timedelta(hours=2, seconds=s, microseconds=us))
+            t = t.replace(tzinfo=tz)
+            self.assertEqual(t.strftime("%z"), "-0200" + z)
 
     def test_extract(self):
         dt = self.theclass(2002, 3, 4, 18, 45, 3, 1234)
@@ -3647,6 +3648,9 @@ class TestDateTimeTZ(TestDateTime, TZInfoBase, unittest.TestCase):
         t2 = self.theclass.min
         self.assertNotEqual(t1, t2)
         self.assertEqual(t2, t2)
+        # and > comparison should fail
+        with self.assertRaises(TypeError):
+            t1 > t2
 
         # It's also naive if it has tzinfo but tzinfo.utcoffset() is None.
         class Naive(tzinfo):
@@ -5073,11 +5077,13 @@ class TestLocalTimeDisambiguation(unittest.TestCase):
         t_fold = datetime(2002, 10, 27, 1, 45, tzinfo=Eastern2)
         t_fold_utc = t_fold.astimezone(timezone.utc)
         self.assertNotEqual(t_fold, t_fold_utc)
+        self.assertNotEqual(t_fold_utc, t_fold)
 
     def test_mixed_compare_gap(self):
         t_gap = datetime(2002, 4, 7, 2, 45, tzinfo=Eastern2)
         t_gap_utc = t_gap.astimezone(timezone.utc)
         self.assertNotEqual(t_gap, t_gap_utc)
+        self.assertNotEqual(t_gap_utc, t_gap)
 
     def test_hash_aware(self):
         t = datetime(2000, 1, 1, tzinfo=Eastern2)