[Python] Getting Attribute error in django BaseCommand- Check

I am working on a tutorial project. The same code works for the instructor but doesn't work for me.

I have a file for custom commands:

from psycopg2 import OperationalError as Psycopg2OpError
from django.db.utils import OperationalError
from django.core.management.base import BaseCommand, CommandError

class Command(BaseCommand):

def handle(self, *args, **options):
self.stdout.write('waiting for database...')

db_up = False
while db_up is False:
try:
self.check(databases=['default'])
db_up = True
except(Psycopg2OpError, OperationalError):
self.stdout.write("Database unavailable, waiting 1 second...")
time.sleep(1)

self.stdout.write(self.style.SUCCESS('Database available!'))


And I am writing test case for the same in a file called test_command.py which is below:

from unittest.mock import patch

from psycopg2 import OperationalError as Psycopg2OpError

from django.core.management import call_command
from django.db.utils import OperationalError
from django.test import SimpleTestCase

@patch('core.management.commands.wait_for_db.Command.Check')
class CommandTests(SimpleTestCase):

def test_wait_for_db_ready(self, patched_check):
"""test waiting for db if db ready"""
patched_check.return_value = True

call_command('wait_for_db')

patched_check.assert_called_once_with(databases=['default'])

@patch('time.sleep')
def test_wait_for_db_delay(self, patched_sleep, patched_check):
"""test waiting for db when getting operational error"""
patched_check.side_effect = [Psycopg2OpError] * 2 + \
[OperationalError] * 3 + [True]

call_command('wait_for_db')
self.assertEqual(patched_check.call_count, 6)
patched_check.assert_called_with(databases=['default'])


When I run the tests, I get an error message- AttributeError: <class 'core.management.commands.wait_for_db.Command'> does not have the attribute 'Check'

I am unable to resolve the error.

The structure of the files are added below:

![Project Structure Here] (https://ibb.co/R44Swzs0)

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