Updated terraform-mr tests

Added changelog for MR
Added poll test for mr_widget_terraform_plan vue

changelogs/unreleased/emilyring-terraform-mr-fix.yml

+---
+title: Remove Visibility from terraform widget
+merge_request: 30737
+author:
+type: fixed

spec/frontend/vue_mr_widget/components/mr_widget_terraform_plan_spec.js

@@ -3,6 +3,7 @@ import { shallowMount } from '@vue/test-utils';
 import axios from '~/lib/utils/axios_utils';
 import MockAdapter from 'axios-mock-adapter';
 import MrWidgetTerraformPlan from '~/vue_merge_request_widget/components/mr_widget_terraform_plan.vue';
+import Poll from '~/lib/utils/poll';
 
 const plan = {
   create: 10,
@@ -57,11 +58,23 @@ describe('MrWidgetTerraformPlan', () => {
   });
 
   describe('successful poll', () => {
+    let pollRequest;
+    let pollStop;
+
     beforeEach(() => {
+      pollRequest = jest.spyOn(Poll.prototype, 'makeRequest');
+      pollStop = jest.spyOn(Poll.prototype, 'stop');
+
       mockPollingApi(200, { 'tfplan.json': plan }, {});
+
       return mountWrapper();
     });
 
+    afterEach(() => {
+      pollRequest.mockRestore();
+      pollStop.mockRestore();
+    });
+
     it('content change text', () => {
       expect(wrapper.find(GlSprintf).exists()).toBe(true);
     });
@@ -69,6 +82,11 @@ describe('MrWidgetTerraformPlan', () => {
     it('renders button when url is found', () => {
       expect(wrapper.find('a').text()).toContain('View full log');
     });
+
+    it('does not make additional requests after poll is successful', () => {
+      expect(pollRequest).toHaveBeenCalledTimes(1);
+      expect(pollStop).toHaveBeenCalledTimes(1);
+    });
   });
 
   describe('polling fails', () => {