Added spec for testing the issuable count

spec/javascripts/fixtures/issuables.html.haml

-.panel.panel-default
-  .panel-heading
-    Unstarted Issues (open and unassigned)
-    .pull-right
-    1

spec/javascripts/milestones_spec.js.es6

-/*= require jquery */
-(() => {
-  describe('MilestonePanel', () => {
-    const issuesCount = '.pull-right';
-    const fixtureTemplate = 'issuables.html';
-
-    function setIssuesCount(newCount) {
-      $(issuesCount).text(newCount);
-    }
-
-    fixture.preload(fixtureTemplate);
-    beforeEach(() => {
-      fixture.load(fixtureTemplate);
-    });
-
-    it('should add delimiter to the issues count', () => {
-      setIssuesCount(1000);
-      expect($(issuesCount).text()).toEqual('1,000');
-    });
-  });
-})();

spec/views/shared/milestones/_issuables.html.haml.rb

+require 'spec_helper'
+
+describe 'shared/milestones/_issuables.html.haml' do
+  let(:issuables_size) { 100 }
+
+  before do
+    allow(view).to receive_messages(title: nil, id: nil, show_project_name: nil,
+                                    show_full_project_name: nil, dom_class: '',
+                                    issuables: double(size: issuables_size).as_null_object)
+
+    stub_template 'shared/milestones/_issuable.html.haml' => ''
+  end
+
+  it 'should show the issuables count if show_counter is true' do
+    render 'shared/milestones/issuables', show_counter: true
+    expect(rendered).to have_content('100')
+  end
+
+  it 'should not show the issuables count if show_counter is false' do
+    render 'shared/milestones/issuables', show_counter: false
+    expect(rendered).not_to have_content('100')
+  end
+
+  describe 'a high issuables count' do
+    let(:issuables_size) { 1000 }
+
+    it 'should show a delimited number if show_counter is true' do
+      render 'shared/milestones/issuables', show_counter: true
+      expect(rendered).to have_content('1,000')
+    end
+  end
+end