add basic on and off buttons

app/controllers/application.js

@@ -0,0 +1,5 @@
+import Ember from 'ember';
+
+export default Ember.Controller.extend({
+  isOn: null
+});

app/routes/application.js

@@ -0,0 +1,16 @@
+import Ember from 'ember';
+
+export default Ember.Route.extend({
+  setupController(controller) {
+    controller.set('isOn', false);
+  },
+  actions: {
+    turnOn() {
+      this.controllerFor('application').set('isOn', true);
+      this.set('isOn', true);
+    },
+    turnOff() {
+      this.controllerFor('application').set('isOn', false);
+    }
+  }
+});

app/templates/application.hbs

@@ -1,3 +1,15 @@
-<h2 id="title">Welcome to Ember</h2>
+<div id="display">
+  {{#if isOn}}
+    ON
+  {{else}}
+    OFF
+  {{/if}}
+</div>
 
-{{outlet}}
+<button {{action 'turnOff'}}>
+  OFF
+</button>
+
+<button {{action 'turnOn'}}>
+  ON
+</button>

tests/unit/controllers/application-test.js

@@ -0,0 +1,12 @@
+import { moduleFor, test } from 'ember-qunit';
+
+moduleFor('controller:application', 'Unit | Controller | application', {
+  // Specify the other units that are required for this test.
+  // needs: ['controller:foo']
+});
+
+// Replace this with your real tests.
+test('it exists', function(assert) {
+  let controller = this.subject();
+  assert.ok(controller);
+});