test_datetime.py 文件源码

def test_tz_aware_arithmetic(self):
        import random

        now = self.theclass.now()
        tz55 = FixedOffset(-330, "west 5:30")
        timeaware = now.time().replace(tzinfo=tz55)
        nowaware = self.theclass.combine(now.date(), timeaware)
        self.assertIs(nowaware.tzinfo, tz55)
        self.assertEqual(nowaware.timetz(), timeaware)

        # Can't mix aware and non-aware.
        self.assertRaises(TypeError, lambda: now - nowaware)
        self.assertRaises(TypeError, lambda: nowaware - now)

        # And adding datetime's doesn't make sense, aware or not.
        self.assertRaises(TypeError, lambda: now + nowaware)
        self.assertRaises(TypeError, lambda: nowaware + now)
        self.assertRaises(TypeError, lambda: nowaware + nowaware)

        # Subtracting should yield 0.
        self.assertEqual(now - now, timedelta(0))
        self.assertEqual(nowaware - nowaware, timedelta(0))

        # Adding a delta should preserve tzinfo.
        delta = timedelta(weeks=1, minutes=12, microseconds=5678)
        nowawareplus = nowaware + delta
        self.assertIs(nowaware.tzinfo, tz55)
        nowawareplus2 = delta + nowaware
        self.assertIs(nowawareplus2.tzinfo, tz55)
        self.assertEqual(nowawareplus, nowawareplus2)

        # that - delta should be what we started with, and that - what we
        # started with should be delta.
        diff = nowawareplus - delta
        self.assertIs(diff.tzinfo, tz55)
        self.assertEqual(nowaware, diff)
        self.assertRaises(TypeError, lambda: delta - nowawareplus)
        self.assertEqual(nowawareplus - nowaware, delta)

        # Make up a random timezone.
        tzr = FixedOffset(random.randrange(-1439, 1440), "randomtimezone")
        # Attach it to nowawareplus.
        nowawareplus = nowawareplus.replace(tzinfo=tzr)
        self.assertIs(nowawareplus.tzinfo, tzr)
        # Make sure the difference takes the timezone adjustments into account.
        got = nowaware - nowawareplus
        # Expected:  (nowaware base - nowaware offset) -
        #            (nowawareplus base - nowawareplus offset) =
        #            (nowaware base - nowawareplus base) +
        #            (nowawareplus offset - nowaware offset) =
        #            -delta + nowawareplus offset - nowaware offset
        expected = nowawareplus.utcoffset() - nowaware.utcoffset() - delta
        self.assertEqual(got, expected)

        # Try max possible difference.
        min = self.theclass(1, 1, 1, tzinfo=FixedOffset(1439, "min"))
        max = self.theclass(MAXYEAR, 12, 31, 23, 59, 59, 999999,
                            tzinfo=FixedOffset(-1439, "max"))
        maxdiff = max - min
        self.assertEqual(maxdiff, self.theclass.max - self.theclass.min +
                                  timedelta(minutes=2*1439))