Specify client attribute of TestCase classes as APIClient

[sidmitra]

• Fixes the following issue when you use self.client in any DRF test class
  Incompatible types in assignment (expression has type "HttpResponse", variable has type "Response")

Description

I've recently upgraded to the latest master of both repos and ran into the above error. The issue seems to be that DRF APITestCase classes seem to be revealing type as HttpResponse instead of drf Response.
The correctclient_class type hints exist here. But this alone doesn't seem enough to correctly type check all uses of the client. If one uses self.client inside a test method the client class still gets Client class instead of APIClient, because of the django-stubs here.

This new error could be because of the recent changes to django-stubs that have surfaced additional type hints?

Sample Test case

from rest_framework.test import APITestCase
from rest_framework.response import Response

class MyTest(APITestCase):
    ...
    
    def test_method(self):
       # error:
       # Incompatible types in assignment (expression has type "HttpResponse", variable has type "Response")
       response: Response = self.client.post("/dummy")

[sobolevn]

Thanks! Can you please also add a test case?

[sidmitra]

@sobolevn Yes will do.

[Goldziher]

This is failing in the pipeline

[Goldziher]

Looking at this - this seems incorrect and not supported by the actual DRF code.

[sidmitra]

@Goldziher You're probably right.

• DRF doesn't seem to define a client attribute here.
• django-stubs is the one adding type hints for this client attribute here, which are perhaps getting inherited by drf-stubs.
  So i was kind of over-riding it to be more precise; But since it breaks tests, will figure out a better way.

Let me figure it out in the next day or so.

[Goldziher]

This PR can be closed @sobolevn

[Goldziher]

Should be closed

[SETTER2000]

response: Any = CurrentClass.client.get('/')
self.assertEqual(len(response.data), 3)