typing: Use assertions for responses when appropriate.

This is part of #18777.

zerver/lib/test_classes.py

@@ -34,6 +34,7 @@ from django.db.migrations.executor import MigrationExecutor
 from django.db.migrations.state import StateApps
 from django.db.utils import IntegrityError
 from django.http import HttpRequest, HttpResponse
+from django.http.response import StreamingHttpResponse
 from django.test import TestCase
 from django.test.client import BOUNDARY, MULTIPART_CONTENT, encode_multipart
 from django.test.testcases import SerializeMixin
@@ -852,6 +853,7 @@ Output:
 
     def assert_url_serves_contents_of_file(self, url: str, result: bytes) -> None:
         response = self.client_get(url)
+        assert isinstance(response, StreamingHttpResponse)
         data = b"".join(response.streaming_content)
         self.assertEqual(result, data)
 

zerver/middleware.py

@@ -2,7 +2,18 @@ import cProfile
 import logging
 import time
 import traceback
-from typing import Any, AnyStr, Callable, Dict, Iterable, List, MutableMapping, Optional, Tuple
+from typing import (
+    Any,
+    AnyStr,
+    Callable,
+    Dict,
+    Iterable,
+    Iterator,
+    List,
+    MutableMapping,
+    Optional,
+    Tuple,
+)
 
 from django.conf import settings
 from django.conf.urls.i18n import is_language_prefix_patterns_used
@@ -394,7 +405,8 @@ class LogRequests(MiddlewareMixin):
                 requestor_for_logs = "unauth@{}".format(get_subdomain(request) or "root")
 
         if response.streaming:
-            content_iter = response.streaming_content
+            assert isinstance(response, StreamingHttpResponse)
+            content_iter: Optional[Iterator[bytes]] = response.streaming_content
             content = None
         else:
             content = response.content
@@ -499,6 +511,7 @@ class LocaleMiddleware(DjangoLocaleMiddleware):
         i18n_patterns_used, _ = is_language_prefix_patterns_used(urlconf)
         if not (i18n_patterns_used and language_from_path):
             patch_vary_headers(response, ("Accept-Language",))
+        assert language is not None
         response.setdefault("Content-Language", language)
 
         # An additional responsibility of our override of this middleware is to save the user's language

zerver/tests/test_upload.py

@@ -12,6 +12,7 @@ from unittest.mock import patch
 import botocore.exceptions
 import orjson
 from django.conf import settings
+from django.http.response import StreamingHttpResponse
 from django.utils.timezone import now as timezone_now
 from django_sendfile.utils import _get_sendfile
 from PIL import Image
@@ -100,6 +101,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         self.logout()
         response = self.api_get(self.example_user("hamlet"), uri)
         self.assertEqual(response.status_code, 200)
+        assert isinstance(response, StreamingHttpResponse)
         data = b"".join(response.streaming_content)
         self.assertEqual(b"zulip!", data)
 
@@ -133,6 +135,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
 
         response = self.client_get(uri, {"api_key": get_api_key(user_profile)})
         self.assertEqual(response.status_code, 200)
+        assert isinstance(response, StreamingHttpResponse)
         data = b"".join(response.streaming_content)
         self.assertEqual(b"zulip!", data)
 
@@ -596,6 +599,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         self.login_user(user_1)
         response = self.client_get(uri, subdomain=test_subdomain)
         self.assertEqual(response.status_code, 200)
+        assert isinstance(response, StreamingHttpResponse)
         data = b"".join(response.streaming_content)
         self.assertEqual(b"zulip!", data)
         self.logout()
@@ -635,6 +639,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         with queries_captured() as queries:
             response = self.client_get(uri)
             self.assertEqual(response.status_code, 200)
+            assert isinstance(response, StreamingHttpResponse)
             data = b"".join(response.streaming_content)
             self.assertEqual(b"zulip!", data)
         self.logout()
@@ -645,6 +650,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         with queries_captured() as queries:
             response = self.client_get(uri)
             self.assertEqual(response.status_code, 200)
+            assert isinstance(response, StreamingHttpResponse)
             data = b"".join(response.streaming_content)
             self.assertEqual(b"zulip!", data)
         self.logout()
@@ -700,6 +706,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         with queries_captured() as queries:
             response = self.client_get(uri)
             self.assertEqual(response.status_code, 200)
+            assert isinstance(response, StreamingHttpResponse)
             data = b"".join(response.streaming_content)
             self.assertEqual(b"zulip!", data)
         self.logout()
@@ -710,6 +717,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         with queries_captured() as queries:
             response = self.client_get(uri)
             self.assertEqual(response.status_code, 200)
+            assert isinstance(response, StreamingHttpResponse)
             data = b"".join(response.streaming_content)
             self.assertEqual(b"zulip!", data)
         self.logout()
@@ -720,6 +728,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         with queries_captured() as queries:
             response = self.client_get(uri)
             self.assertEqual(response.status_code, 200)
+            assert isinstance(response, StreamingHttpResponse)
             data = b"".join(response.streaming_content)
             self.assertEqual(b"zulip!", data)
         self.logout()
@@ -783,6 +792,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         with queries_captured() as queries:
             response = self.client_get(uri)
             self.assertEqual(response.status_code, 200)
+            assert isinstance(response, StreamingHttpResponse)
             data = b"".join(response.streaming_content)
             self.assertEqual(b"zulip!", data)
         # If we were accidentally one query per message, this would be 20+
@@ -815,6 +825,7 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         for user in subscribed_users + unsubscribed_users:
             self.login_user(user)
             response = self.client_get(uri)
+            assert isinstance(response, StreamingHttpResponse)
             data = b"".join(response.streaming_content)
             self.assertEqual(b"zulip!", data)
             self.logout()
@@ -1124,6 +1135,7 @@ class AvatarTest(UploadSerializeMixin, ZulipTestCase):
 
             if rfname is not None:
                 response = self.client_get(url)
+                assert isinstance(response, StreamingHttpResponse)
                 data = b"".join(response.streaming_content)
                 self.assertEqual(Image.open(io.BytesIO(data)).size, (100, 100))
 
@@ -1376,6 +1388,7 @@ class RealmIconTest(UploadSerializeMixin, ZulipTestCase):
 
             if rfname is not None:
                 response = self.client_get(url)
+                assert isinstance(response, StreamingHttpResponse)
                 data = b"".join(response.streaming_content)
                 self.assertEqual(Image.open(io.BytesIO(data)).size, (100, 100))
 
@@ -1547,6 +1560,7 @@ class RealmLogoTest(UploadSerializeMixin, ZulipTestCase):
 
             if rfname is not None:
                 response = self.client_get(logo_url)
+                assert isinstance(response, StreamingHttpResponse)
                 data = b"".join(response.streaming_content)
                 # size should be 100 x 100 because thumbnail keeps aspect ratio
                 # while trying to fit in a 800 x 100 box without losing part of the image