ruff: Fix RUF015 Prefer `next(...)` over single element slice.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

analytics/management/commands/populate_analytics_db.py

@@ -155,7 +155,7 @@ class Command(BaseCommand):
             table: Type[BaseCount],
         ) -> None:
             end_times = time_range(
-                last_end_time, last_end_time, stat.frequency, len(list(fixture_data.values())[0])
+                last_end_time, last_end_time, stat.frequency, len(next(iter(fixture_data.values())))
             )
             if table == InstallationCount:
                 id_args: Dict[str, Any] = {}

corporate/views/portico.py

@@ -126,6 +126,11 @@ def communities_view(request: HttpRequest) -> HttpResponse:
     for realm in want_to_be_advertised_realms:
         open_to_public = not realm.invite_required and not realm.emails_restricted_to_domains
         if realm.allow_web_public_streams_access() or open_to_public:
+            [org_type] = (
+                org_type
+                for org_type in Realm.ORG_TYPES
+                if Realm.ORG_TYPES[org_type]["id"] == realm.org_type
+            )
             eligible_realms.append(
                 {
                     "id": realm.id,
@@ -133,11 +138,7 @@ def communities_view(request: HttpRequest) -> HttpResponse:
                     "realm_url": realm.uri,
                     "logo_url": get_realm_icon_url(realm),
                     "description": get_realm_text_description(realm),
-                    "org_type_key": [
+                    "org_type_key": org_type,
-                        org_type
-                        for org_type in Realm.ORG_TYPES
-                        if Realm.ORG_TYPES[org_type]["id"] == realm.org_type
-                    ][0],
                 }
             )
             unique_org_type_ids.add(realm.org_type)

tools/tests/test_zulint_custom_rules.py

@@ -55,10 +55,10 @@ class TestRuleList(TestCase):
                     )
 
             for line in rule.get("bad_lines", []):
+                for filename in rule.get("include_only", {"foo.bar"}):
                     with patch(
                         "builtins.open", return_value=StringIO(line + "\n\n"), autospec=True
                     ), patch("builtins.print"):
-                    filename = list(rule.get("include_only", {"foo.bar"}))[0]
                         self.assertTrue(
                             RuleList([], [rule]).custom_check_file(filename, "baz", ""),
                             f"The pattern '{pattern}' didn't match the line '{line}' while it should.",

zerver/lib/event_schema.py

@@ -453,11 +453,9 @@ def check_presence(
     assert isinstance(event["presence"], dict)
 
     # Our tests only have one presence value.
-    assert len(event["presence"]) == 1
+    [(event_presence_key, event_presence_value)] = event["presence"].items()
-
+    assert event_presence_key == presence_key
-    assert list(event["presence"].keys())[0] == presence_key
+    assert event_presence_value["status"] == status
-
-    assert list(event["presence"].values())[0]["status"] == status
 
 
 # Type for the legacy user field; the `user_id` field is intended to

zerver/lib/markdown/__init__.py

@@ -1152,8 +1152,9 @@ class InlineInterestingLinkProcessor(markdown.treeprocessors.Treeprocessor):
             ):
                 return insertion_index
 
-            uncle_link = list(uncle.iter(tag="a"))[0].attrib["href"]
+            uncle_link = uncle.find("a")
-            if uncle_link not in parent_links:
+            assert uncle_link is not None
+            if uncle_link.attrib["href"] not in parent_links:
                 return insertion_index
 
     def run(self, root: Element) -> None:

zerver/lib/test_classes.py

@@ -1542,7 +1542,8 @@ Output:
         return values
 
     def find_by_id(self, data: List[Dict[str, Any]], db_id: int) -> Dict[str, Any]:
-        return [r for r in data if r["id"] == db_id][0]
+        [r] = (r for r in data if r["id"] == db_id)
+        return r
 
     def init_default_ldap_database(self) -> None:
         """

zerver/openapi/python_examples.py

@@ -623,10 +623,10 @@ def get_user_groups(client: Client) -> int:
     # {code_example|end}
 
     validate_against_openapi_schema(result, "/user_groups", "get", "200")
-    hamlet_user_group = [u for u in result["user_groups"] if u["name"] == "hamletcharacters"][0]
+    [hamlet_user_group] = (u for u in result["user_groups"] if u["name"] == "hamletcharacters")
     assert hamlet_user_group["description"] == "Characters of Hamlet"
 
-    marketing_user_group = [u for u in result["user_groups"] if u["name"] == "marketing"][0]
+    [marketing_user_group] = (u for u in result["user_groups"] if u["name"] == "marketing")
     return marketing_user_group["id"]
 
 

zerver/tests/test_auth_backends.py

@@ -3698,7 +3698,7 @@ class GenericOpenIdConnectTest(SocialAuthBase):
         account_data_dict = self.get_account_data_dict(email=email, name=name)
 
         oidc_setting_dict = copy.deepcopy(settings.SOCIAL_AUTH_OIDC_ENABLED_IDPS)
-        idp_settings_dict = list(oidc_setting_dict.values())[0]
+        [idp_settings_dict] = oidc_setting_dict.values()
         idp_settings_dict["auto_signup"] = True
         with mock.patch.object(GenericOpenIdConnectBackend, "settings_dict", new=idp_settings_dict):
             result = self.social_auth_test(
@@ -3748,7 +3748,7 @@ class GenericOpenIdConnectTest(SocialAuthBase):
         account_data_dict = self.get_account_data_dict(email=self.email, name=self.name)
 
         mock_oidc_setting_dict = copy.deepcopy(settings.SOCIAL_AUTH_OIDC_ENABLED_IDPS)
-        idp_config_dict = list(mock_oidc_setting_dict.values())[0]
+        [idp_config_dict] = mock_oidc_setting_dict.values()
         del idp_config_dict["client_id"]
         with self.settings(SOCIAL_AUTH_OIDC_ENABLED_IDPS=mock_oidc_setting_dict):
             result = self.social_auth_test(
@@ -3763,7 +3763,7 @@ class GenericOpenIdConnectTest(SocialAuthBase):
         account_data_dict = self.get_account_data_dict(email=self.email, name=self.name)
 
         mock_oidc_setting_dict = copy.deepcopy(settings.SOCIAL_AUTH_OIDC_ENABLED_IDPS)
-        idp_config_dict = list(mock_oidc_setting_dict.values())[0]
+        [idp_config_dict] = mock_oidc_setting_dict.values()
         mock_oidc_setting_dict["secondprovider"] = idp_config_dict
         with self.settings(SOCIAL_AUTH_OIDC_ENABLED_IDPS=mock_oidc_setting_dict):
             result = self.social_auth_test(

zerver/tests/test_event_system.py

@@ -585,9 +585,9 @@ class GetEventsTest(ZulipTestCase):
             self.assert_json_success(result)
             self.assert_length(events, 1)
 
-            pronouns_field = [
+            [pronouns_field] = (
                 field for field in events[0]["fields"] if field["id"] == profile_field.id
-            ][0]
+            )
             if pronouns_field_type_supported:
                 expected_type = CustomProfileField.PRONOUNS
             else:
@@ -794,9 +794,7 @@ class FetchInitialStateDataTest(ZulipTestCase):
         )
         self.assertIn("custom_profile_fields", result)
         custom_profile_fields = result["custom_profile_fields"]
-        pronouns_field = [field for field in custom_profile_fields if field["name"] == "Pronouns"][
+        [pronouns_field] = (field for field in custom_profile_fields if field["name"] == "Pronouns")
-            0
-        ]
         self.assertEqual(pronouns_field["type"], CustomProfileField.SHORT_TEXT)
 
         result = fetch_initial_state_data(
@@ -805,9 +803,7 @@ class FetchInitialStateDataTest(ZulipTestCase):
         )
         self.assertIn("custom_profile_fields", result)
         custom_profile_fields = result["custom_profile_fields"]
-        pronouns_field = [field for field in custom_profile_fields if field["name"] == "Pronouns"][
+        [pronouns_field] = (field for field in custom_profile_fields if field["name"] == "Pronouns")
-            0
-        ]
         self.assertEqual(pronouns_field["type"], CustomProfileField.PRONOUNS)
 
 

zerver/tests/test_events.py

@@ -1080,9 +1080,9 @@ class NormalActionsTest(BaseAction):
             pronouns_field_type_supported=True,
         )
         check_custom_profile_fields("events[0]", events[0])
-        pronouns_field = [
+        [pronouns_field] = (
             field_obj for field_obj in events[0]["fields"] if field_obj["id"] == field.id
-        ][0]
+        )
         self.assertEqual(pronouns_field["type"], CustomProfileField.PRONOUNS)
 
         hint = "What pronouns should people use to refer you?"
@@ -1091,9 +1091,9 @@ class NormalActionsTest(BaseAction):
             pronouns_field_type_supported=False,
         )
         check_custom_profile_fields("events[0]", events[0])
-        pronouns_field = [
+        [pronouns_field] = (
             field_obj for field_obj in events[0]["fields"] if field_obj["id"] == field.id
-        ][0]
+        )
         self.assertEqual(pronouns_field["type"], CustomProfileField.SHORT_TEXT)
 
     def test_custom_profile_field_data_events(self) -> None:

zerver/tests/test_gitter_importer.py

@@ -95,16 +95,16 @@ class GitterImporter(ZulipTestCase):
         self.assertIn(messages["zerver_message"][0]["content"], "test message")
 
         # test usermessages and soft-deactivation of users
-        user_should_be_long_term_idle = [
+        [user_should_be_long_term_idle] = (
             user
             for user in realm["zerver_userprofile"]
             if user["delivery_email"] == "username1@users.noreply.github.com"
-        ][0]
+        )
-        user_should_not_be_long_term_idle = [
+        [user_should_not_be_long_term_idle] = (
             user
             for user in realm["zerver_userprofile"]
             if user["delivery_email"] == "username2@users.noreply.github.com"
-        ][0]
+        )
         self.assertEqual(user_should_be_long_term_idle["long_term_idle"], True)
 
         # Only the user who's not soft-deactivated gets UserMessages.

zerver/tests/test_message_fetch.py

@@ -2812,7 +2812,7 @@ class GetOldMessagesTest(ZulipTestCase):
             '<p>昨日、<span class="highlight">日本</span>のお菓子を送りました。</p>',
         )
 
-        english_message = [m for m in messages if m[TOPIC_NAME] == "english"][0]
+        [english_message] = (m for m in messages if m[TOPIC_NAME] == "english")
         self.assertEqual(english_message[MATCH_TOPIC], "english")
         self.assertEqual(
             english_message["match_content"],

zerver/tests/test_message_send.py

@@ -586,9 +586,7 @@ class MessagePOSTTest(ZulipTestCase):
         message_id = orjson.loads(result.content)["id"]
 
         recent_conversations = get_recent_private_conversations(user_profile)
-        self.assert_length(recent_conversations, 1)
+        [(recipient_id, recent_conversation)] = recent_conversations.items()
-        recent_conversation = list(recent_conversations.values())[0]
-        recipient_id = list(recent_conversations.keys())[0]
         self.assertEqual(set(recent_conversation["user_ids"]), {othello.id})
         self.assertEqual(recent_conversation["max_message_id"], message_id)
 
@@ -612,8 +610,7 @@ class MessagePOSTTest(ZulipTestCase):
 
         # Now verify we have the appropriate self-pm data structure
         del recent_conversations[recipient_id]
-        recent_conversation = list(recent_conversations.values())[0]
+        [(recipient_id, recent_conversation)] = recent_conversations.items()
-        recipient_id = list(recent_conversations.keys())[0]
         self.assertEqual(set(recent_conversation["user_ids"]), set())
         self.assertEqual(recent_conversation["max_message_id"], self_message_id)
 
@@ -1997,8 +1994,7 @@ class StreamMessagesTest(ZulipTestCase):
         self.assert_length(msg_data["huddle_dict"].keys(), 2)
 
         recent_conversations = get_recent_private_conversations(users[1])
-        self.assert_length(recent_conversations, 1)
+        [recent_conversation] = recent_conversations.values()
-        recent_conversation = list(recent_conversations.values())[0]
         self.assertEqual(
             set(recent_conversation["user_ids"]), {user.id for user in users if user != users[1]}
         )

zerver/tests/test_users.py

@@ -2158,7 +2158,7 @@ class BulkUsersTest(ZulipTestCase):
             data = dict(client_gravatar=orjson.dumps(client_gravatar).decode())
             result = self.client_get("/json/users", data)
             rows = self.assert_json_success(result)["members"]
-            hamlet_data = [row for row in rows if row["user_id"] == hamlet.id][0]
+            [hamlet_data] = (row for row in rows if row["user_id"] == hamlet.id)
             return hamlet_data["avatar_url"]
 
         self.assertEqual(

zerver/views/realm_emoji.py

@@ -40,7 +40,7 @@ def upload_emoji(
         raise JsonableError(_("You must upload exactly one file."))
     if emoji_name in valid_built_in_emoji and not user_profile.is_realm_admin:
         raise JsonableError(_("Only administrators can override default emoji."))
-    emoji_file = list(request.FILES.values())[0]
+    [emoji_file] = request.FILES.values()
     assert isinstance(emoji_file, UploadedFile)
     assert emoji_file.size is not None
     if (settings.MAX_EMOJI_FILE_SIZE_MIB * 1024 * 1024) < emoji_file.size:

zerver/views/realm_icon.py

@@ -19,7 +19,7 @@ def upload_icon(request: HttpRequest, user_profile: UserProfile) -> HttpResponse
     if len(request.FILES) != 1:
         raise JsonableError(_("You must upload exactly one icon."))
 
-    icon_file = list(request.FILES.values())[0]
+    [icon_file] = request.FILES.values()
     assert isinstance(icon_file, UploadedFile)
     assert icon_file.size is not None
     if (settings.MAX_ICON_FILE_SIZE_MIB * 1024 * 1024) < icon_file.size:

zerver/views/realm_logo.py

@@ -25,7 +25,7 @@ def upload_logo(
 
     if len(request.FILES) != 1:
         raise JsonableError(_("You must upload exactly one logo."))
-    logo_file = list(request.FILES.values())[0]
+    [logo_file] = request.FILES.values()
     assert isinstance(logo_file, UploadedFile)
     assert logo_file.size is not None
     if (settings.MAX_LOGO_FILE_SIZE_MIB * 1024 * 1024) < logo_file.size:

zerver/views/upload.py

@@ -269,7 +269,7 @@ def upload_file_backend(request: HttpRequest, user_profile: UserProfile) -> Http
     if len(request.FILES) != 1:
         raise JsonableError(_("You may only upload one file at a time"))
 
-    user_file = list(request.FILES.values())[0]
+    [user_file] = request.FILES.values()
     assert isinstance(user_file, UploadedFile)
     file_size = user_file.size
     assert file_size is not None

zerver/views/user_settings.py

@@ -363,7 +363,7 @@ def set_avatar_backend(request: HttpRequest, user_profile: UserProfile) -> HttpR
     if avatar_changes_disabled(user_profile.realm) and not user_profile.is_realm_admin:
         raise JsonableError(str(AVATAR_CHANGES_DISABLED_ERROR))
 
-    user_file = list(request.FILES.values())[0]
+    [user_file] = request.FILES.values()
     assert isinstance(user_file, UploadedFile)
     assert user_file.size is not None
     if (settings.MAX_AVATAR_FILE_SIZE_MIB * 1024 * 1024) < user_file.size:

zerver/views/users.py

@@ -414,7 +414,7 @@ def patch_bot_backend(
     if len(request.FILES) == 0:
         pass
     elif len(request.FILES) == 1:
-        user_file = list(request.FILES.values())[0]
+        [user_file] = request.FILES.values()
         assert isinstance(user_file, UploadedFile)
         assert user_file.size is not None
         upload_avatar_image(user_file, user_profile, bot)
@@ -556,7 +556,7 @@ def add_bot_backend(
         acting_user=user_profile,
     )
     if len(request.FILES) == 1:
-        user_file = list(request.FILES.values())[0]
+        [user_file] = request.FILES.values()
         assert isinstance(user_file, UploadedFile)
         assert user_file.size is not None
         upload_avatar_image(user_file, user_profile, bot_profile)

zproject/backends.py

@@ -2844,9 +2844,8 @@ class GenericOpenIdConnectBackend(SocialAuthMixin, OpenIdConnectAuth):
 
     # Hack: We don't yet support multiple IdPs, but we want this
     # module to import if nothing has been configured yet.
-    settings_dict: OIDCIdPConfigDict = list(
+    settings_dict: OIDCIdPConfigDict
-        settings.SOCIAL_AUTH_OIDC_ENABLED_IDPS.values() or [OIDCIdPConfigDict()]
+    [settings_dict] = settings.SOCIAL_AUTH_OIDC_ENABLED_IDPS.values() or [OIDCIdPConfigDict()]
-    )[0]
 
     display_icon: Optional[str] = settings_dict.get("display_icon", None)
     display_name: str = settings_dict.get("display_name", "OIDC")
@@ -2871,7 +2870,7 @@ class GenericOpenIdConnectBackend(SocialAuthMixin, OpenIdConnectAuth):
             return False
 
         mandatory_config_keys = ["oidc_url", "client_id", "secret"]
-        idp_config_dict = list(settings.SOCIAL_AUTH_OIDC_ENABLED_IDPS.values())[0]
+        [idp_config_dict] = settings.SOCIAL_AUTH_OIDC_ENABLED_IDPS.values()
         if not all(idp_config_dict.get(key) for key in mandatory_config_keys):
             return False