diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
@@ -303,6 +303,8 @@ def test_tzname(self):
        self.assertEqual('UTC+09:30', timezone(9.5 * HOUR).tzname(None))
        self.assertEqual('UTC-00:01', timezone(timedelta(minutes=-1)).tzname(None))
        self.assertEqual('XYZ', timezone(-5 * HOUR, 'XYZ').tzname(None))

        # Sub-minute offsets:
        self.assertEqual('UTC+01:06:40', timezone(timedelta(0, 4000)).tzname(None))
@@ -1308,6 +1310,12 @@ def test_strftime(self):
            except ValueError:
                pass

        #check that this standard extension works
        t.strftime("%f")

@@ -1747,6 +1755,9 @@ def test_isoformat(self):
        self.assertEqual(t.isoformat('T'), "0001-02-03T04:05:01.000123")
        self.assertEqual(t.isoformat(' '), "0001-02-03 04:05:01.000123")
        self.assertEqual(t.isoformat('\x00'), "0001-02-03\x0004:05:01.000123")
        self.assertEqual(t.isoformat(timespec='hours'), "0001-02-03T04")
        self.assertEqual(t.isoformat(timespec='minutes'), "0001-02-03T04:05")
        self.assertEqual(t.isoformat(timespec='seconds'), "0001-02-03T04:05:01")
@@ -1755,6 +1766,8 @@ def test_isoformat(self):
        self.assertEqual(t.isoformat(timespec='auto'), "0001-02-03T04:05:01.000123")
        self.assertEqual(t.isoformat(sep=' ', timespec='minutes'), "0001-02-03 04:05")
        self.assertRaises(ValueError, t.isoformat, timespec='foo')
        # str is ISO format with the separator forced to a blank.
        self.assertEqual(str(t), "0001-02-03 04:05:01.000123")

@@ -2286,6 +2299,19 @@ def test_strptime(self):
        self.assertIs(type(expected), self.theclass)
        self.assertIs(type(got), self.theclass)

        strptime = self.theclass.strptime
        self.assertEqual(strptime("+0002", "%z").utcoffset(), 2 * MINUTE)
        self.assertEqual(strptime("-0002", "%z").utcoffset(), -2 * MINUTE)
@@ -2353,6 +2379,12 @@ def test_more_strftime(self):
            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)
        self.assertEqual(dt.date(), date(2002, 3, 4))
@@ -2878,6 +2910,8 @@ def test_isoformat(self):
        self.assertEqual(t.isoformat(timespec='microseconds'), "12:34:56.123456")
        self.assertEqual(t.isoformat(timespec='auto'), "12:34:56.123456")
        self.assertRaises(ValueError, t.isoformat, timespec='monkey')

        t = self.theclass(hour=12, minute=34, second=56, microsecond=999500)
        self.assertEqual(t.isoformat(timespec='milliseconds'), "12:34:56.999")
@@ -2928,6 +2962,12 @@ def test_strftime(self):
        # A naive object replaces %z and %Z with empty strings.
        self.assertEqual(t.strftime("'%z' '%Z'"), "'' ''")

    def test_format(self):
        t = self.theclass(1, 2, 3, 4)
        self.assertEqual(t.__format__(''), str(t))