DEV: Fix core backend CI tests timing out (#34281)

The test cases added in 470b2891c5 caused
core backend tests to start timing out on CI because MessageBus messages
were being processed in a background thread outside of the current
database transation.

We are currently working around the problem by updating the test cases
to just assert that the right MessageBus message is being published.

lib/site_setting_extension.rb

@@ -448,11 +448,13 @@ module SiteSettingExtension
     end
   end
 
+  SITE_SETTINGS_CHANNEL = "/site_settings"
+
   def ensure_listen_for_changes
     return if @listen_for_changes == false
 
     unless @subscribed
-      MessageBus.subscribe("/site_settings") do |message|
+      MessageBus.subscribe(SITE_SETTINGS_CHANNEL) do |message|
         process_message(message) if message.data["process"] != process_id
       end
 

lib/site_settings/local_process_provider.rb

@@ -21,8 +21,6 @@ class SiteSettings::LocalProcessProvider
     end
   end
 
-  attr_accessor :model
-
   def settings
     @settings[current_site] ||= {}
   end
@@ -49,10 +47,6 @@ class SiteSettings::LocalProcessProvider
     end
     setting.value = value.to_s
 
-    # So we can simulate the MessageBus notifications
-    # done by the DbProvider
-    @model.notify_changed! if @model
-
     setting
   end
 

spec/lib/site_setting_extension_spec.rb

@@ -41,12 +41,6 @@ RSpec.describe SiteSettingExtension do
     new_settings(provider_local)
   end
 
-  after do
-    settings.provider.model = nil
-    settings.listen_for_changes = false
-    settings2.listen_for_changes = false
-  end
-
   it "does not leak state cause changes are not linked" do
     t1 =
       Thread.new do
@@ -72,7 +66,12 @@ RSpec.describe SiteSettingExtension do
     t2.join
   end
 
-  describe "refresh!" do
+  describe ".refresh!" do
+    it "ensures that the right MessageBus subscription has been set up" do
+      settings.expects(:ensure_listen_for_changes).once
+      settings.refresh!
+    end
+
     it "will reset to default if provider vanishes" do
       settings.setting(:hello, 1)
       settings.hello = 100
@@ -110,30 +109,6 @@ RSpec.describe SiteSettingExtension do
       expect(settings2.hello).to eq(99)
     end
 
-    it "publishes changes across processes" do
-      MessageBus.on
-
-      # Only need to do this once, since both settings will use the same provider. Doing it twice leads to confusion with MessageBus
-      settings.provider.model = settings
-
-      settings.listen_for_changes = true
-      settings2.listen_for_changes = true
-
-      settings.refresh!
-      settings2.refresh!
-
-      settings.setting(:hello, 1)
-      settings2.setting(:hello, 1)
-
-      settings.hello = 100
-
-      expect(settings2.hello).to eq(100)
-
-      settings.hello = 99
-
-      try_until_success(frequency: 0.5) { expect(settings2.hello).to eq(99) }
-    end
-
     it "does not override types in the type supervisor" do
       settings.setting(:foo, "bar")
       settings.provider.save(:foo, "bar", SiteSetting.types[:enum])
@@ -1078,36 +1053,29 @@ RSpec.describe SiteSettingExtension do
       expect(SiteSetting.search_experience(theme_id: theme_2.id)).to eq("search_field")
     end
 
-    it "publishes changes across processes" do
-      MessageBus.on
-
+    it "publishes the right MessageBus message when a theme site setting is updated" do
       settings_tss_instance_1 = new_settings(provider_local)
-      settings_tss_instance_2 = new_settings(provider_local)
-
-      settings_tss_instance_1.listen_for_changes = true
-      settings_tss_instance_2.listen_for_changes = true
-
       settings_tss_instance_1.load_settings(File.join(Rails.root, "config", "site_settings.yml"))
-      settings_tss_instance_2.load_settings(File.join(Rails.root, "config", "site_settings.yml"))
-
       settings_tss_instance_1.refresh!
-      settings_tss_instance_2.refresh!
 
       expect(settings_tss_instance_1.enable_welcome_banner(theme_id: theme_1.id)).to eq(false)
-      expect(settings_tss_instance_2.enable_welcome_banner(theme_id: theme_1.id)).to eq(false)
 
       tss_1.update!(value: true)
-      settings_tss_instance_1.change_themeable_site_setting(
-        theme_1.id,
-        :enable_welcome_banner,
-        true,
-      )
 
-      # Get through the MessageBus queue
-      try_until_success(frequency: 0.5) do
-        expect(settings_tss_instance_1.enable_welcome_banner(theme_id: theme_1.id)).to eq(true)
-        expect(settings_tss_instance_2.enable_welcome_banner(theme_id: theme_1.id)).to eq(true)
-      end
+      messages =
+        MessageBus.track_publish(described_class::SITE_SETTINGS_CHANNEL) do
+          settings_tss_instance_1.change_themeable_site_setting(
+            theme_1.id,
+            :enable_welcome_banner,
+            true,
+          )
+        end
+
+      expect(messages.length).to eq(1)
+
+      message = messages.first
+
+      expect(message.data[:process]).to eq(settings_tss_instance_1.process_id)
     end
 
     describe ".theme_site_settings_json_uncached" do

spec/lib/site_settings/db_provider_spec.rb

@@ -20,7 +20,10 @@ RSpec.describe SiteSettings::DbProvider do
     expect(provider.all.length).to eq(0)
     expect(provider.find("test")).to eq(nil)
 
+    SiteSetting.expects(:notify_changed!).at_least_once
+
     provider.save("test", "one", 1)
+
     found = provider.find("test")
 
     expect_same_setting(found, setting.new("test", "one", 1))