Improve readability and add test

app/models/project_services/chat_notification_service.rb

@@ -17,7 +17,7 @@ class ChatNotificationService < Service
     if properties.nil?
       self.properties = {}
       self.notify_only_broken_pipelines = true
-      self.notify_only_default_branch = false
+      self.notify_only_default_branch = true
     end
   end
 
@@ -137,20 +137,17 @@ class ChatNotificationService < Service
   end
 
   def should_pipeline_be_notified?(data)
-    notify_for_branch(data) && notify_for_pipeline(data)
+    notify_for_ref?(data) && notify_for_pipeline?(data)
   end
 
-  def notify_for_branch(data)
-    ref_type = data[:object_attributes][:tag] ? 'tag' : 'branch'
+  def notify_for_ref?(data)
+    return true if data[:object_attributes][:tag]
+    return true unless notify_only_default_branch
 
-    if ref_type == 'branch' && notify_only_default_branch
-      data[:object_attributes][:ref] == project.default_branch
-    else
-      true
-    end
+    data[:object_attributes][:ref] == project.default_branch
   end
 
-  def notify_for_pipeline(data)
+  def notify_for_pipeline?(data)
     case data[:object_attributes][:status]
     when 'success'
       !notify_only_broken_pipelines?

spec/features/admin/admin_settings_spec.rb

@@ -34,6 +34,7 @@ feature 'Admin updates settings', feature: true do
     fill_in 'Username', with: 'test_user'
     fill_in 'service_push_channel', with: '#test_channel'
     page.check('Notify only broken pipelines')
+    page.check('Notify only default branch')
 
     check_all_events
     click_on 'Save'

spec/support/slack_mattermost_notifications_shared_examples.rb

@@ -324,5 +324,24 @@ RSpec.shared_examples 'slack or mattermost notifications' do
         it_behaves_like 'call Slack/Mattermost API'
       end
     end
+
+    context 'only notify for the default branch' do
+      context 'when enabled' do
+        let(:pipeline) do
+          create(:ci_pipeline, project: project, status: 'failed', ref: 'not-the-default-branch')
+        end
+
+        before do
+          chat_service.notify_only_default_branch = true
+        end
+
+        it 'does not call the Slack/Mattermost API for pipeline events' do
+          data = Gitlab::DataBuilder::Pipeline.build(pipeline)
+          result = chat_service.execute(data)
+
+          expect(result).to be_falsy
+        end
+      end
+    end
   end
 end