FIX: Update client lastReadMessageId on trashed message (#21697)

Followup ae3231e140, when a
message is trashed we already update the lastReadMessageId of
all users in the channel to the latest non-deleted message on
the server side. However we didn't propagate this to the client,
so in some cases when we did the following:

1. Delete the last message in the channel
2. Switch to another channel
3. Switch back to the original

We would get a 404 error from the target message ID being looked
up still being the old lastReadMessageId (now deleted) for the
user's channel membership.

All we need to do is send the last not-deleted message ID for
the channel (or thread) to all the member users.

plugins/chat/spec/services/chat/publisher_spec.rb

@@ -6,6 +6,39 @@ describe Chat::Publisher do
   fab!(:channel) { Fabricate(:category_channel) }
   fab!(:message) { Fabricate(:chat_message, chat_channel: channel) }
 
+  describe ".publish_delete!" do
+    fab!(:message_2) { Fabricate(:chat_message, chat_channel: channel) }
+    before { message.trash! }
+
+    it "publishes the correct data" do
+      data = MessageBus.track_publish { described_class.publish_delete!(channel, message) }[0].data
+
+      expect(data["deleted_at"]).to eq(message.deleted_at.iso8601(3))
+      expect(data["deleted_id"]).to eq(message.id)
+      expect(data["latest_not_deleted_message_id"]).to eq(message_2.id)
+      expect(data["type"]).to eq("delete")
+    end
+
+    context "when the message is in a thread and the channel has threading_enabled" do
+      before do
+        SiteSetting.enable_experimental_chat_threaded_discussions = true
+        thread = Fabricate(:chat_thread, channel: channel)
+        message.update!(thread: thread)
+        channel.update!(threading_enabled: true)
+      end
+
+      it "publishes the correct latest not deleted message id" do
+        data =
+          MessageBus.track_publish { described_class.publish_delete!(channel, message) }[0].data
+
+        expect(data["deleted_at"]).to eq(message.deleted_at.iso8601(3))
+        expect(data["deleted_id"]).to eq(message.id)
+        expect(data["latest_not_deleted_message_id"]).to eq(message.thread.original_message_id)
+        expect(data["type"]).to eq("delete")
+      end
+    end
+  end
+
   describe ".publish_refresh!" do
     it "publishes the message" do
       data = MessageBus.track_publish { described_class.publish_refresh!(channel, message) }[0].data

plugins/chat/spec/services/chat/trash_message_spec.rb

@@ -66,6 +66,7 @@ RSpec.describe Chat::TrashMessage do
               "type" => "delete",
               "deleted_id" => message.id,
               "deleted_at" => message.reload.deleted_at.iso8601(3),
+              "latest_not_deleted_message_id" => nil,
             },
           )
         end

plugins/chat/spec/system/deleted_message_spec.rb

@@ -3,6 +3,7 @@
 RSpec.describe "Deleted message", type: :system, js: true do
   let(:chat_page) { PageObjects::Pages::Chat.new }
   let(:channel_page) { PageObjects::Pages::ChatChannel.new }
+  let(:sidebar_component) { PageObjects::Components::Sidebar.new }
 
   fab!(:current_user) { Fabricate(:admin) }
   fab!(:channel_1) { Fabricate(:category_channel) }
@@ -28,6 +29,22 @@ RSpec.describe "Deleted message", type: :system, js: true do
         count: 1,
       )
     end
+
+    it "does not error when coming back to the channel from another channel" do
+      message = Fabricate(:chat_message, chat_channel: channel_1)
+      channel_2 = Fabricate(:category_channel, name: "other channel")
+      channel_2.add(current_user)
+      channel_1
+        .user_chat_channel_memberships
+        .find_by(user: current_user)
+        .update!(last_read_message_id: message.id)
+      chat_page.visit_channel(channel_1)
+      channel_page.delete_message(message)
+      expect(channel_page).to have_deleted_message(message, count: 1)
+      sidebar_component.click_link(channel_2.name)
+      sidebar_component.click_link(channel_1.name)
+      expect(channel_page).to have_deleted_message(message, count: 1)
+    end
   end
 
   context "when deleting multiple messages" do