比较python中的两个日期并忽略微秒

Question

我将date_added日期时间值插入到不支持datetime（6）的mysql 5.5中，这在运行以下单元测试时导致AssertionError

foo.date_added = timezone.now()

self.assertEquals(only_foo_in_database.date_added, foo.date_added)

这导致

AssertionError: datetime.datetime(2013, 9, 2, 6, 48, 56, tzinfo=<UTC>) != datetime.datetime(2013, 9, 2, 6, 48, 56, 677255, tzinfo=<UTC>)

如何比较忽略微秒的两个日期时间值？

Answer 1

使用datetime.datetime.replace将microsecond设置为0 ：

>>> d = datetime.datetime.now()
>>> d
datetime.datetime(2013, 9, 2, 16, 25, 59, 444433)
>>> d.replace(microsecond=0)
datetime.datetime(2013, 9, 2, 16, 25, 59)

---

self.assertEquals(only_foo_in_database.date_added.replace(microsecond=0),
                  foo.date_added.replace(microsecond=0))

备选

使用datetime.timedelta ：

d1 = datetime.datetime(2013,9,2,6,48,56)
d2 = datetime.datetime(2013,9,2,6,48,56,677255)
self.assertTrue(abs(d1 - d2) < datetime.timedelta(seconds=1))

Answer 2

您可以在unittest中使用assertAlmostEqual

from django.utils import timezone as tz
self.assertAlmostEqual(
    only_foo_in_database.date_added, foo.date_added,
    delta=tz.timedelta(seconds=1))