oops here's the test

test/javascripts/widgets/topic-participant-test.js.es6

@@ -0,0 +1,43 @@
+import { moduleForWidget, widgetTest } from 'helpers/widget-test';
+
+moduleForWidget('topic-participant');
+
+widgetTest('one post', {
+  template: '{{mount-widget widget="topic-participant" args=args}}',
+
+  setup() {
+    this.set('args', {
+      username: 'test',
+      avatar_template: 'stubbed',
+      post_count: 1
+    });
+  },
+
+  test(assert) {
+    assert.ok(exists('a.poster.trigger-user-card'));
+    assert.ok(!exists('span.post-count'), "don't show count for only 1 post");
+    assert.ok(!exists('.avatar-flair'), "no avatar flair");
+  }
+});
+
+widgetTest('many posts, a primary group with flair', {
+  template: '{{mount-widget widget="topic-participant" args=args}}',
+
+  setup() {
+    this.set('args', {
+      username: 'test',
+      avatar_template: 'stubbed',
+      post_count: 5,
+      primary_group_name: 'devs',
+      primary_group_flair_url: "http://devs.example.com/img/devs.png",
+      primary_group_flair_bg_color: "222"
+    });
+  },
+
+  test(assert) {
+    assert.ok(exists('a.poster.trigger-user-card'));
+    assert.ok(exists('span.post-count'), "show count for many posts");
+    assert.ok(exists('.group-devs a.poster'), "add class for the group outside the link");
+    assert.ok(exists('.avatar-flair.avatar-flair-devs'), "show flair with group class");
+  }
+});