What is the correct way to make a mockup to test a request?

Question

Django

Let's say I have some API (greatly simplified):
api.py :

from some.app import some_external_check

class SomeViewSet(GenericViewSet):
    ...
    @action(detail=False, methods=['POST'], permission_classes=(permissions.IsAuthenticated, ))
    def somefunc(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        result = some_external_check(serializer.validated_data)   # <-- вот тут надо пропатчить результат вызова на определенное значение
        ...
        # какие-то вычисления дальше
        return Response(someresult)

And I make a test for it:
tests.py :

from unittest.mock import Mock, patch
from rest_framework import status
from rest_framework.test import APITestCase, APIClient

class SomeAPITest(APITestCase):
    ...
    def test_somefunc(self):
        my_client = APIClient()
        my_client.credentials(HTTP_AUTHORIZATION=f'Token {SOMETOKEN}') 
        ...
        response = my_client.post(reverse('some-url-for-somefunc-api'), data=data, format='json')
        self.assertEqual(response.status_code, status.HTTP_200_OK)
        # тут тестирую результат вызова
        ...

So, how to write a test using Mock or any other library without embedding in the code itself, so that the call to the some_external_check function is patched with the return of some specific value for the purpose of further testing?
And how is it generally done correctly?

Answer 1

In general - since there are no answers - I will describe one of the options used, maybe it will help someone:
On the test run, in addition to working containers, a wiremock container was also raised , which simulated the operation of an external REST service, and the main project was connected to it based on the settings derived from environment variables.