DEV: Add support for limit in notifications index w/o recent param (#24423)

Currently to use a limit in the notifications index, you have to also pass recent: true as a param.

This PR:

Adds optional limit param to be used in the notifications query, regardless of the presence of recent
Raises the max limit of the response with recent present from 50 -> 60. It is super weird we have a hard-limit of 50 before with recent param, and 60 without the param.

app/controllers/notifications_controller.rb

@@ -5,7 +5,7 @@ class NotificationsController < ApplicationController
   before_action :ensure_admin, only: %i[create update destroy]
   before_action :set_notification, only: %i[update destroy]
 
-  INDEX_LIMIT = 50
+  INDEX_LIMIT = 60
 
   def index
     user =
@@ -72,6 +72,7 @@ class NotificationsController < ApplicationController
 
       render_json_dump(json)
     else
+      limit = fetch_limit_from_params(default: INDEX_LIMIT, max: INDEX_LIMIT)
       offset = params[:offset].to_i
 
       notifications =
@@ -82,7 +83,7 @@ class NotificationsController < ApplicationController
       notifications = notifications.where(read: false) if params[:filter] == "unread"
 
       total_rows = notifications.dup.count
-      notifications = notifications.offset(offset).limit(60)
+      notifications = notifications.offset(offset).limit(limit)
       notifications =
         Notification.filter_inaccessible_topic_notifications(current_user.guardian, notifications)
       render_json_dump(
@@ -90,7 +91,12 @@ class NotificationsController < ApplicationController
         total_rows_notifications: total_rows,
         seen_notification_id: user.seen_notification_id,
         load_more_notifications:
-          notifications_path(username: user.username, offset: offset + 60, filter: params[:filter]),
+          notifications_path(
+            username: user.username,
+            offset: offset + limit,
+            limit: limit,
+            filter: params[:filter],
+          ),
       )
     end
   end

spec/requests/notifications_controller_spec.rb

@@ -90,12 +90,34 @@ RSpec.describe NotificationsController do
         describe "when limit params is invalid" do
           include_examples "invalid limit params",
                            "/notifications.json",
-                           described_class::INDEX_LIMIT,
+                           described_class::INDEX_LIMIT + 1,
                            params: {
                              recent: true,
                            }
         end
 
+        it "respects limit param and properly bumps offset for load_more_notifications URL" do
+          7.times { notification = Fabricate(:notification, user: user) }
+
+          get "/notifications.json", params: { username: user.username, limit: 2 }
+          expect(response.parsed_body["notifications"].count).to eq(2)
+          expect(response.parsed_body["load_more_notifications"]).to eq(
+            "/notifications?limit=2&offset=2&username=#{user.username}",
+          )
+
+          # Same as response above but we need .json added before query params.
+          get "/notifications.json?limit=2&offset=2&username=#{user.username}"
+          expect(response.parsed_body["load_more_notifications"]).to eq(
+            "/notifications?limit=2&offset=4&username=#{user.username}",
+          )
+
+          # We are seeing that the offset is increasing properly and limit is staying the same
+          get "/notifications.json?limit=2&offset=4&username=#{user.username}"
+          expect(response.parsed_body["load_more_notifications"]).to eq(
+            "/notifications?limit=2&offset=6&username=#{user.username}",
+          )
+        end
+
         it "get notifications with all filters" do
           notification = Fabricate(:notification, user: user)
           notification2 = Fabricate(:notification, user: user)