FE fetch counts async on search page load

Creates `refresh_counts` module to dynamically fetch
and load data based on attributes of HAML elements.

app/assets/javascripts/pages/search/show/refresh_counts.js

+import axios from '~/lib/utils/axios_utils';
+
+function showCount(el, count) {
+  el.textContent = count;
+  el.classList.remove('hidden');
+}
+
+function refreshCount(el) {
+  const { url } = el.dataset;
+
+  return axios
+    .get(url)
+    .then(({ data }) => showCount(el, data.count))
+    .catch(e => {
+      // eslint-disable-next-line no-console
+      console.error(`Failed to fetch search count from '${url}'.`, e);
+    });
+}
+
+export default function refreshCounts() {
+  const elements = Array.from(document.querySelectorAll('.js-search-count'));
+
+  return Promise.all(elements.map(refreshCount));
+}

app/assets/javascripts/pages/search/show/search.js

@@ -3,6 +3,7 @@ import Flash from '~/flash';
 import Api from '~/api';
 import { __ } from '~/locale';
 import Project from '~/pages/projects/project';
+import refreshCounts from './refresh_counts';
 
 export default class Search {
   constructor() {
@@ -14,6 +15,7 @@ export default class Search {
 
     this.groupId = $groupDropdown.data('groupId');
     this.eventListeners();
+    refreshCounts();
 
     $groupDropdown.glDropdown({
       selectable: true,

app/helpers/search_helper.rb

@@ -155,16 +155,15 @@ module SearchHelper
       li_class = 'active'
       count = @search_results.formatted_count(scope)
     else
-      count = 0
-      badge_class = 'js-search-count'
-      badge_data = { scope: scope, url: search_count_path(search_params) }
+      badge_class = 'js-search-count hidden'
+      badge_data = { url: search_count_path(search_params) }
     end
 
     content_tag :li, class: li_class, data: data do
       link_to search_path(search_params) do
         concat label
         concat ' '
-        concat content_tag(:span, count, class: 'badge badge-pill', data: { scope: scope })
+        concat content_tag(:span, count, class: ['badge badge-pill', badge_class], data: badge_data)
       end
     end
   end

spec/frontend/pages/search/show/__snapshots__/refresh_counts_spec.js.snap

+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`pages/search/show/refresh_counts fetches and displays search counts 1`] = `
+"<div class=\\"badge\\">22</div>
+<div class=\\"badge js-search-count\\" data-url=\\"http://test.host/search/count?search=lorem+ipsum&amp;project_id=3&amp;scope=issues\\">4</div>
+<div class=\\"badge js-search-count\\" data-url=\\"http://test.host/search/count?search=lorem+ipsum&amp;project_id=3&amp;scope=merge_requests\\">5</div>"
+`;

spec/frontend/pages/search/show/refresh_counts_spec.js

+import MockAdapter from 'axios-mock-adapter';
+import { TEST_HOST } from 'helpers/test_constants';
+import axios from '~/lib/utils/axios_utils';
+import refreshCounts from '~/pages/search/show/refresh_counts';
+
+const URL = `${TEST_HOST}/search/count?search=lorem+ipsum&project_id=3`;
+const urlWithScope = scope => `${URL}&scope=${scope}`;
+const counts = [{ scope: 'issues', count: 4 }, { scope: 'merge_requests', count: 5 }];
+const fixture = `<div class="badge">22</div>
+<div class="badge js-search-count hidden" data-url="${urlWithScope('issues')}"></div>
+<div class="badge js-search-count hidden" data-url="${urlWithScope('merge_requests')}"></div>`;
+
+describe('pages/search/show/refresh_counts', () => {
+  let mock;
+
+  beforeEach(() => {
+    mock = new MockAdapter(axios);
+    setFixtures(fixture);
+  });
+
+  afterEach(() => {
+    mock.restore();
+  });
+
+  it('fetches and displays search counts', () => {
+    counts.forEach(({ scope, count }) => {
+      mock.onGet(urlWithScope(scope)).reply(200, { count });
+    });
+
+    // assert before act behavior
+    return refreshCounts().then(() => {
+      expect(document.body.innerHTML).toMatchSnapshot();
+    });
+  });
+});