DEV: Introduce bulk channel tracking publisher (#20838)

This commit introduces a Chat::Publisher and MessageBus endpoint
that allows for updating a user's channel tracking state in bulk for
multiple channels, rather than having to do it for one channel
at a time.

This also required an improvement to ChannelUnreadsQuery -- now
multiple channel IDs can be passed to this to get the unread counts
and mention counts for those channels for a user, also increasing
efficiency rather than having to do a query for every individual
channel.

Followup to #20802

plugins/chat/spec/queries/chat/channel_unreads_query_spec.rb

@@ -13,39 +13,91 @@ describe Chat::ChannelUnreadsQuery do
   end
 
   context "with unread message" do
-    it "returns a correct unread count" do
-      Fabricate(:chat_message, chat_channel: channel_1)
+    before { Fabricate(:chat_message, chat_channel: channel_1) }
 
-      expect(described_class.call(channel_id: channel_1.id, user_id: current_user.id)).to eq(
-        { mention_count: 0, unread_count: 1 },
-      )
+    it "returns a correct unread count" do
+      expect(
+        described_class.call(channel_ids: [channel_1.id], user_id: current_user.id).first.to_h,
+      ).to eq({ mention_count: 0, unread_count: 1, channel_id: channel_1.id })
+    end
+
+    context "for multiple channels" do
+      fab!(:channel_2) { Fabricate(:category_channel) }
+
+      it "returns accurate counts" do
+        channel_2.add(current_user)
+        Fabricate(:chat_message, chat_channel: channel_2)
+        Fabricate(:chat_message, chat_channel: channel_2)
+
+        expect(
+          described_class.call(
+            channel_ids: [channel_1.id, channel_2.id],
+            user_id: current_user.id,
+          ).map(&:to_h),
+        ).to match_array(
+          [
+            { mention_count: 0, unread_count: 1, channel_id: channel_1.id },
+            { mention_count: 0, unread_count: 2, channel_id: channel_2.id },
+          ],
+        )
+      end
     end
   end
 
   context "with unread mentions" do
     before { Jobs.run_immediately! }
 
-    it "returns a correct unread mention" do
-      message = Fabricate(:chat_message)
+    def create_mention(message, channel)
       notification =
         Notification.create!(
           notification_type: Notification.types[:chat_mention],
           user_id: current_user.id,
-          data: { chat_message_id: message.id, chat_channel_id: channel_1.id }.to_json,
+          data: { chat_message_id: message.id, chat_channel_id: channel.id }.to_json,
         )
       Chat::Mention.create!(notification: notification, user: current_user, chat_message: message)
+    end
 
-      expect(described_class.call(channel_id: channel_1.id, user_id: current_user.id)).to eq(
-        { mention_count: 1, unread_count: 0 },
-      )
+    it "returns a correct unread mention" do
+      message = Fabricate(:chat_message, chat_channel: channel_1)
+      create_mention(message, channel_1)
+
+      expect(
+        described_class.call(channel_ids: [channel_1.id], user_id: current_user.id).first.to_h,
+      ).to eq({ mention_count: 1, unread_count: 1, channel_id: channel_1.id })
+    end
+
+    context "for multiple channels" do
+      fab!(:channel_2) { Fabricate(:category_channel) }
+
+      it "returns accurate counts" do
+        message = Fabricate(:chat_message, chat_channel: channel_1)
+        create_mention(message, channel_1)
+
+        channel_2.add(current_user)
+        Fabricate(:chat_message, chat_channel: channel_2)
+        message_2 = Fabricate(:chat_message, chat_channel: channel_2)
+        create_mention(message_2, channel_2)
+
+        expect(
+          described_class.call(
+            channel_ids: [channel_1.id, channel_2.id],
+            user_id: current_user.id,
+          ).map(&:to_h),
+        ).to match_array(
+          [
+            { mention_count: 1, unread_count: 1, channel_id: channel_1.id },
+            { mention_count: 1, unread_count: 2, channel_id: channel_2.id },
+          ],
+        )
+      end
     end
   end
 
   context "with nothing unread" do
     it "returns a correct state" do
-      expect(described_class.call(channel_id: channel_1.id, user_id: current_user.id)).to eq(
-        { mention_count: 0, unread_count: 0 },
-      )
+      expect(
+        described_class.call(channel_ids: [channel_1.id], user_id: current_user.id).first.to_h,
+      ).to eq({ mention_count: 0, unread_count: 0, channel_id: channel_1.id })
     end
   end
 end

plugins/chat/spec/services/chat/mark_all_user_channels_read_spec.rb

@@ -129,11 +129,30 @@ RSpec.describe Chat::MarkAllUserChannelsRead do
         }.by(-2)
       end
 
-      it "publishes tracking state for all affected channels" do
-        messages = MessageBus.track_publish { result }
-        expect(
-          messages.select { |m| m.channel == "/chat/user-tracking-state/#{current_user.id}" }.count,
-        ).to eq(3)
+      it "publishes tracking state in bulk for affected channels" do
+        message =
+          messages.find { |m| m.channel == "/chat/bulk-user-tracking-state/#{current_user.id}" }
+
+        expect(message.data).to eq(
+          channel_1.id.to_s => {
+            "last_read_message_id" => message_2.id,
+            "membership_id" => membership_1.id,
+            "mention_count" => 0,
+            "unread_count" => 0,
+          },
+          channel_2.id.to_s => {
+            "last_read_message_id" => message_4.id,
+            "membership_id" => membership_2.id,
+            "mention_count" => 0,
+            "unread_count" => 0,
+          },
+          channel_3.id.to_s => {
+            "last_read_message_id" => message_6.id,
+            "membership_id" => membership_3.id,
+            "mention_count" => 0,
+            "unread_count" => 0,
+          },
+        )
       end
     end
   end