'unique_for_date/year/month checks shouldn\'t trigger when the
associated DateField is None.'

def test_unique_for_date_with_nullable_date(self):

    FlexibleDatePost.objects.create(title='Django    1.0    is    released', slug='Django    1.0', subtitle='Finally', posted=datetime.date(2008, 9, 3))
    p = FlexibleDatePost(title='Django    1.0    is    released')
    p.full_clean()
    p = FlexibleDatePost(slug='Django    1.0')
    p.full_clean()
    p = FlexibleDatePost(subtitle='Finally')
    p.full_clean()
