Assert that the scale up/down indicator is not shown when the count is null

ui/app/models/scale-event.js

@@ -11,6 +11,11 @@ export default class ScaleEvent extends Fragment {
   @attr('boolean') error;
   @attr('string') evalId;
 
+  @computed('count', function() {
+    return this.count != null;
+  })
+  hasCount;
+
   @computed('count', 'previousCount', function() {
     return this.count > this.previousCount;
   })

ui/app/templates/components/scale-events-accordion.hbs

@@ -10,7 +10,7 @@
         </span>
       </div>
       <div class="column is-2">
-        {{#if (gte a.item.count 0)}}
+        {{#if a.item.hasCount}}
           <span data-test-count-icon>
             {{#if a.item.increased}}
               {{x-icon "arrow-up" class="is-danger"}}

ui/tests/integration/components/scale-events-accordion-test.js

@@ -93,7 +93,8 @@ module('Integration | Component | scale-events-accordion', function(hooks) {
 
     await render(commonTemplate);
 
-    assert.equal(find('[data-test-count]').textContent, '');
+    assert.notOk(find('[data-test-count]'));
+    assert.notOk(find('[data-test-count-icon]'));
   });
 
   test('when an event has no meta properties, the accordion entry is not expandable', async function(assert) {