FIX: streaming related specs (#1448)

## 🔍 Overview
This update fixes an issue where message bus streaming related specs
were not working correctly. To do so we pass the `last_id` when
subscribing to `MessageBus` which allows us to unskip those broken
tests.

---------

Co-authored-by: Joffrey JAFFEUX <j.jaffeux@gmail.com>

assets/javascripts/discourse/components/modal/diff-modal.gjs

@@ -85,14 +85,18 @@ export default class ModalDiffModal extends Component {
 
   @bind
   subscribe() {
-    this.messageBus.subscribe(CHANNEL, this.updateResult);
+    this.messageBus.subscribe(
+      CHANNEL,
+      this.updateResult,
+      this.currentUser
+        ?.discourse_ai_helper_stream_composer_suggestion_last_message_bus_id
+    );
   }
 
   @bind
   cleanup() {
     // stop all callbacks so it does not end up streaming pointlessly
-    this.smoothStreamer.resetStreaming();
+    this.#resetState();
-    this.diffStreamer.reset();
     this.messageBus.unsubscribe(CHANNEL, this.updateResult);
   }
 

lib/ai_helper/entry_point.rb

@@ -79,6 +79,12 @@ module DiscourseAi
           :discourse_ai_helper_stream_suggestion_last_message_bus_id,
           include_condition: -> { SiteSetting.ai_helper_enabled && scope.authenticated? },
         ) { MessageBus.last_id("/discourse-ai/ai-helper/stream_suggestion/#{object.id}") }
+
+        plugin.add_to_serializer(
+          :current_user,
+          :discourse_ai_helper_stream_composer_suggestion_last_message_bus_id,
+          include_condition: -> { SiteSetting.ai_helper_enabled && scope.authenticated? },
+        ) { MessageBus.last_id("/discourse-ai/ai-helper/stream_composer_suggestion") }
       end
     end
   end

spec/system/ai_helper/ai_composer_helper_spec.rb

@@ -9,6 +9,7 @@ RSpec.describe "AI Composer helper", type: :system, js: true do
     Group.find_by(id: Group::AUTO_GROUPS[:admins]).add(user)
     assign_fake_provider_to(:ai_helper_model)
     SiteSetting.ai_helper_enabled = true
+    Jobs.run_immediately!
     sign_in(user)
   end
 
@@ -80,7 +81,6 @@ RSpec.describe "AI Composer helper", type: :system, js: true do
       end
 
       it "replaces the composed message with AI generated content" do
-        skip("Message bus updates not appearing in tests")
         trigger_composer_helper(input)
         ai_helper_menu.fill_custom_prompt(custom_prompt_input)
 
@@ -109,7 +109,6 @@ RSpec.describe "AI Composer helper", type: :system, js: true do
       let(:spanish_input) { "La lluvia en España se queda principalmente en el avión." }
 
       it "replaces the composed message with AI generated content" do
-        skip("Message bus updates not appearing in tests")
         trigger_composer_helper(spanish_input)
 
         DiscourseAi::Completions::Llm.with_prepared_responses([input]) do
@@ -121,7 +120,6 @@ RSpec.describe "AI Composer helper", type: :system, js: true do
       end
 
       it "reverts results when Ctrl/Cmd + Z is pressed on the keyboard" do
-        skip("Message bus updates not appearing in tests")
         trigger_composer_helper(spanish_input)
 
         DiscourseAi::Completions::Llm.with_prepared_responses([input]) do
@@ -134,7 +132,6 @@ RSpec.describe "AI Composer helper", type: :system, js: true do
       end
 
       it "shows the changes in a modal" do
-        skip("Message bus updates not appearing in tests")
         trigger_composer_helper(spanish_input)
 
         DiscourseAi::Completions::Llm.with_prepared_responses([input]) do
@@ -168,7 +165,6 @@ RSpec.describe "AI Composer helper", type: :system, js: true do
       let(:proofread_text) { "The rain in Spain, stays mainly in the Plane." }
 
       it "replaces the composed message with AI generated content" do
-        skip("Message bus updates not appearing in tests")
         trigger_composer_helper(input)
 
         DiscourseAi::Completions::Llm.with_prepared_responses([proofread_text]) do

spec/system/ai_helper/ai_proofreading_spec.rb

@@ -23,7 +23,6 @@ RSpec.describe "AI Composer Proofreading Features", type: :system, js: true do
 
   context "when triggering via keyboard shortcut" do
     it "proofreads selected text" do
-      skip("Animation causing diff not to appear correctly in specs")
       visit "/new-topic"
       composer.fill_content("hello worldd !")
 
@@ -38,7 +37,6 @@ RSpec.describe "AI Composer Proofreading Features", type: :system, js: true do
     end
 
     it "proofreads all text when nothing is selected" do
-      skip("Animation causing diff not to appear correctly in specs")
       visit "/new-topic"
       composer.fill_content("hello worrld")
 
@@ -65,7 +63,6 @@ RSpec.describe "AI Composer Proofreading Features", type: :system, js: true do
       before { SiteSetting.rich_editor = true }
 
       it "proofreads selected text and replaces it" do
-        skip("Animation causing diff not to appear correctly in specs")
         visit "/new-topic"
         expect(composer).to be_opened
         composer.toggle_rich_editor