Why is my django unittest failing a constraint? - python-3.x

Question

I have this model:
class TestopiaEvent(Model):
event_id = AutoField(primary_key=True)
name = CharField(max_length=255)
start_date = DateField()
end_date = DateField()
testers_required = IntegerField()
class Meta:
constraints = [
CheckConstraint(
check=Q(start_date__lte=F('end_date'), start_date__gte=datetime.now().date()),
name='correct_datetime'
)
]
And this test:
class TestopiaEventTestCase(TestCase):
def setUp(self):
self.default_values = {
'name': 'Testopia 1',
'start_date': datetime.now().date(),
'end_date': datetime.now().date() + timedelta(days=1),
'testers_required': 1
}
self.testopia_event = TestopiaEvent(**self.default_values)
def test_save_with_valid_model_check_database(self):
self.assertIsNone(self.testopia_event.save())
And it fails with this error:
django.db.utils.IntegrityError: new row for relation "webserver_testopiaevent" violates check constraint "correct_datetime"
DETAIL: Failing row contains (1, Testopia 1, 2020-07-24 00:00:00+00, 2020-07-25 00:00:00+00, 1).
I don't understand why it is failing as it should only fail if today's date is less than the start date and the start date or/and the start date is greater than the end date, which it isn't?
What have I done wrong? Thanks
Edit: Here are the postgresdb constraints:
testopia=# \d+ webserver_testopiaevent
Table
"public.webserver_testopiaevent"
Column | Type | Collation | Nullable | Default | Storage | Stats target | Description
------------------+------------------------+-----------+----------+-----------------------------------------------------------+----------+--------------+-------------
event_id | integer | | not null | nextval('webserver_testopiaevent_event_id_seq'::regclass) | plain | |
name | character varying(255) | | not null | | extended | |
start_date | date | | not null | | plain | |
end_date | date | | not null | | plain | |
testers_required | integer | | not null | | plain | |
Indexes:
"webserver_testopiaevent_pkey" PRIMARY KEY, btree (event_id)
Check constraints:
"correct_datetime" CHECK (start_date >= statement_timestamp() AND start_date <= end_date)
Access method: heap

Answer 1

Now() returns a DateTimeField() so with the timestamp addition it will be more than the current date if my DateField is set to the same date.