💄 replace DownloadCountPoller with gh-download-count

closes https://github.com/TryGhost/Ghost/issues/8321
- adds `gh-download-count` component that uses ember-concurrency to poll the count endpoint
- removes the no-longer-needed `setup/one` route as ember-concurrency now handles the setInterval bookkeeping for us

ghost/admin/app/components/gh-download-count.js

@@ -0,0 +1,41 @@
+import Ember from 'ember';
+import Component from 'ember-component';
+import injectService from 'ember-service/inject';
+import {task, timeout} from 'ember-concurrency';
+
+const {testing} = Ember;
+const INTERVAL = testing ? 20 : 2000;
+
+export default Component.extend({
+    ajax: injectService(),
+    ghostPaths: injectService(),
+
+    count: '',
+
+    _poll: task(function* () {
+        let url = this.get('ghostPaths.count');
+        let pattern = /(-?\d+)(\d{3})/;
+
+        try {
+            let data = yield this.get('ajax').request(url);
+            let count = data.count.toString();
+
+            while (pattern.test(count)) {
+                count = count.replace(pattern, '$1,$2');
+            }
+
+            this.set('count', count);
+
+            if (!testing) {
+                yield timeout(INTERVAL);
+                this.get('_poll').perform();
+            }
+        } catch (e) {
+            // no-op - we don't want to create noise for a failed download count
+        }
+    }),
+
+    didInsertElement() {
+        this.get('_poll').perform();
+    }
+});

ghost/admin/app/routes/setup/one.js

@@ -1,68 +0,0 @@
-import Ember from 'ember';
-import Route from 'ember-route';
-import injectService from 'ember-service/inject';
-import EmberObject from 'ember-object';
-import run from 'ember-runloop';
-
-import AjaxService from 'ember-ajax/services/ajax';
-
-// ember-cli-shims doesn't export Ember.testing
-const {testing} = Ember;
-
-let DownloadCountPoller = EmberObject.extend({
-    url: null,
-    count: '',
-    runId: null,
-
-    ajax: AjaxService.create(),
-    notifications: injectService(),
-
-    init() {
-        this._super(...arguments);
-        this.downloadCounter();
-        this.poll();
-    },
-
-    poll() {
-        let interval = testing ? 20 : 2000;
-        let runId = run.later(this, function () {
-            this.downloadCounter();
-            if (!testing) {
-                this.poll();
-            }
-        }, interval);
-
-        this.set('runId', runId);
-    },
-
-    downloadCounter() {
-        this.get('ajax').request(this.get('url')).then((data) => {
-            let pattern = /(-?\d+)(\d{3})/;
-            let count = data.count.toString();
-
-            while (pattern.test(count)) {
-                count = count.replace(pattern, '$1,$2');
-            }
-
-            this.set('count', count);
-        }).catch((error) => {
-            this.set('count', '');
-            this.get('notifications').showAPIError(error);
-        });
-    }
-});
-
-export default Route.extend({
-    ghostPaths: injectService(),
-
-    model() {
-        return DownloadCountPoller.create({url: this.get('ghostPaths.count')});
-    },
-
-    resetController(controller, isExiting) {
-        if (isExiting) {
-            run.cancel(controller.get('model.runId'));
-            controller.set('model', null);
-        }
-    }
-});

ghost/admin/app/templates/components/gh-download-count.hbs

@@ -0,0 +1,5 @@
+{{#if hasBlock}}
+    {{yield count}}
+{{else}}
+    {{count}}
+{{/if}}

ghost/admin/app/templates/setup/one.hbs

@@ -1,6 +1,6 @@
 <header>
     <h1>Welcome to <strong>Ghost</strong>!</h1>
-    <p>All over the world, people have started <em>{{model.count}}</em> incredible blogs with Ghost. Today, we’re starting yours.</p>
+    <p>All over the world, people have started <em>{{gh-download-count}}</em> incredible blogs with Ghost. Today, we’re starting yours.</p>
 </header>
 
 <figure class="gh-flow-screenshot">

ghost/admin/tests/acceptance/setup-test.js

@@ -100,9 +100,8 @@ describe('Acceptance: Setup', function () {
                     .to.be.false;
 
                 // it displays download count (count increments for each ajax call
-                // and polling is disabled in testing so our count should be "2" -
-                // 1 for first load and 1 for first poll)
-                expect(find('.gh-flow-content em').text()).to.equal('2');
+                // and polling is disabled in testing so our count should be "1"
+                expect(find('.gh-flow-content em').text().trim()).to.equal('1');
             });
 
             click('.gh-btn-green');

ghost/admin/tests/integration/components/gh-download-count-test.js

@@ -0,0 +1,45 @@
+import {expect} from 'chai';
+import {describe, it} from 'mocha';
+import {setupComponentTest} from 'ember-mocha';
+import hbs from 'htmlbars-inline-precompile';
+import Pretender from 'pretender';
+import wait from 'ember-test-helpers/wait';
+
+describe('Integration: Component: gh-download-count', function() {
+    setupComponentTest('gh-download-count', {
+        integration: true
+    });
+
+    let server;
+
+    beforeEach(function () {
+        server = new Pretender();
+        server.get('https://count.ghost.org/', function () {
+            return [200, {}, JSON.stringify({count: 42})];
+        });
+    });
+
+    afterEach(function () {
+        server.shutdown();
+    });
+
+    it('hits count endpoint and renders', function () {
+        this.render(hbs`{{gh-download-count}}`);
+
+        return wait().then(() => {
+            expect(this.$().text().trim()).to.equal('42');
+        });
+    });
+
+    it('renders with a block', function () {
+        this.render(hbs`
+            {{#gh-download-count as |count|}}
+                {{count}} downloads
+            {{/gh-download-count}}
+        `);
+
+        return wait().then(() => {
+            expect(this.$().text().trim()).to.equal('42 downloads');
+        });
+    });
+});