PERF: calculate topic_counts for tags in an async job so tag queries that include counts are much faster

test/javascripts/acceptance/tags-test.js.es6

@@ -8,4 +8,57 @@ QUnit.test("list the tags", assert => {
     assert.ok($('body.tags-page').length, "has the body class");
     assert.ok(exists('.tag-eviltrout'), "shows the evil trout tag");
   });
-});
+});
+
+acceptance("Tags listed by group", {
+  loggedIn: true,
+  settings: {
+    tags_listed_by_group: true
+  }
+});
+
+
+QUnit.test("list the tags in groups", assert => {
+  server.get('/tags', () => { // eslint-disable-line no-undef
+    return [
+      200,
+      { "Content-Type": "application/json" },
+      {
+        "tags":[{id: 'planned', text: 'planned', count: 7}],
+        "extras": { "tag_groups": [
+          {id: 2, name: "Ford Cars", tags: [
+            {id: 'escort', text: 'escort', count: 1},
+            {id: 'focus', text: 'focus', count: 3}
+          ]},
+          {id: 1, name: "Honda Cars", tags: [
+            {id: 'civic', text: 'civic', count: 4},
+            {id: 'accord', text: 'accord', count: 2}
+          ]},
+          {id: 1, name: "Makes", tags: [
+            {id: 'ford', text: 'ford', count: 5},
+            {id: 'honda', text: 'honda', count: 6}
+          ]}
+        ]}
+      }
+    ];
+  });
+
+  visit('/tags');
+  andThen(() => {
+    assert.equal($('.tag-list').length, 4, "shows separate lists for the 3 groups and the ungrouped tags");
+    assert.ok(
+      _.isEqual(
+        _.map($('.tag-list h3'), i => { return $(i).text(); } ),
+        ['Ford Cars', 'Honda Cars', 'Makes', 'Other Tags']
+      ),
+      'shown in given order and with tags that are not in a group'
+    );
+    assert.ok(
+      _.isEqual(
+        _.map($('.tag-list:first .discourse-tag'), i => { return $(i).text(); }),
+        ['focus', 'escort']
+      ),
+      'shows the tags in default sort (by count)'
+    );
+  });
+});