Add tests for ChatNotificationService#execute

spec/models/project_services/chat_notification_service_spec.rb

@@ -26,4 +26,54 @@ describe ChatNotificationService do
       end
     end
   end
+
+  describe '#execute' do
+    let(:chat_service) { described_class.new }
+    let(:user) { create(:user) }
+    let(:project) { create(:project, :repository) }
+    let(:webhook_url) { 'https://example.gitlab.com/' }
+
+    before do
+      allow(chat_service).to receive_messages(
+        project: project,
+        project_id: project.id,
+        service_hook: true,
+        webhook: webhook_url
+      )
+
+      WebMock.stub_request(:post, webhook_url)
+
+      subject.active = true
+    end
+
+    context 'with a repository' do
+      it 'returns true' do
+        subject.project = project
+        data = Gitlab::DataBuilder::Push.build_sample(project, user)
+
+        expect(Slack::Notifier).to receive(:new)
+         .with(webhook_url, {})
+         .and_return(
+           double(:slack_service).as_null_object
+         )
+
+        expect(chat_service.execute(data)).to be true
+      end
+    end
+
+    context 'with an empty repository' do
+      it 'returns true' do
+        subject.project = create(:project, :empty_repo)
+        data = Gitlab::DataBuilder::Push.build_sample(subject.project, user)
+
+        expect(Slack::Notifier).to receive(:new)
+         .with(webhook_url, {})
+         .and_return(
+           double(:slack_service).as_null_object
+         )
+
+        expect(chat_service.execute(data)).to be true
+      end
+    end
+  end
 end