disables test settings on chat notification services when repository is empty

app/models/project_services/chat_notification_service.rb

@@ -22,7 +22,7 @@ class ChatNotificationService < Service
   end
   def can_test?
-    valid?
+    super && valid?
   end
   def self.supported_events

changelogs/unreleased/31009-disable-test-settings-on-services-when-repository-is-empty.yml

+---
+title: Disable test settings on chat notification services when repository is empty
+merge_request: 10759
+author:

spec/models/project_services/chat_notification_service_spec.rb

 require 'spec_helper'
 describe ChatNotificationService, models: true do
-  describe "Associations" do
+  describe 'Associations' do
     before do
       allow(subject).to receive(:activated?).and_return(true)
     end
     it { is_expected.to validate_presence_of :webhook }
   end
+
+  describe '#can_test?' do
+    context 'with empty repository' do
+      it 'returns false' do
+        subject.project = create(:empty_project, :empty_repo)
+
+        expect(subject.can_test?).to be false
+      end
+    end
+
+    context 'with repository' do
+      it 'returns true' do
+        subject.project = create(:project)
+
+        expect(subject.can_test?).to be true
+      end
+    end
+  end
 end