[ci skip] Adds tests for placeholder note component

spec/javascripts/notes/components/issue_note_form_spec.js

@@ -27,7 +27,6 @@ describe('issue_note_form component', () => {
 
     });
 
-
     describe('keyboard events', () => {
       describe('up', () => {
         it('should ender edit mode', () => {

spec/javascripts/notes/components/issue_placeholder_note_spec.js

+import Vue from 'vue';
+import issuePlaceholderNote from '~/notes/components/issue_placeholder_note.vue';
+import store from '~/notes/stores';
+import { userDataMock } from '../mock_data';
+
 describe('issue placeholder system note component', () => {
+  let vm;
+
   beforeEach(() => {
+    const Component = Vue.extend(issuePlaceholderNote);
+    store.dispatch('setUserData', userDataMock);
+    vm = new Component({
+      store,
+      propsData: { note: { body: 'Foo' } },
+    }).$mount();
   });
 
   describe('user information', () => {
     it('should render user avatar with link', () => {
-
+      expect(vm.$el.querySelector('.user-avatar-link').getAttribute('href')).toEqual(userDataMock.path);
+      expect(vm.$el.querySelector('.user-avatar-link img').getAttribute('src')).toEqual(userDataMock.avatar_url);
     });
   });
 
   describe('note content', () => {
     it('should render note header information', () => {
-
+      expect(vm.$el.querySelector('.note-header-info a').getAttribute('href')).toEqual(userDataMock.path);
+      expect(vm.$el.querySelector('.note-header-info .note-headline-light').textContent.trim()).toEqual(`@${userDataMock.username}`);
     });
 
     it('should render note body', () => {
-
-    });
-
-    it('should render system note placeholder with markdown', () => {
-
-    });
-
-    it('should render emojis', () => {
-
-    });
-
-    it('should render slash commands', () => {
-
+      expect(vm.$el.querySelector('.note-text p').textContent.trim()).toEqual('Foo');
     });
   });
 });