Ensure service is fastboot compatible. Specifically with using `scrol… (

#98)

* Ensure service is fastboot compatible. Specifically with using `scrollElement`

* fix: prevent call to document with isFastboot

addon/services/router-scroll.js

@@ -1,11 +1,15 @@
 /* eslint-disable */
-import Ember from 'ember';
 import Service from '@ember/service';
 import { getWithDefault, computed, set, get } from '@ember/object';
-
-const { getOwner, typeOf } = Ember;
+import { typeOf } from '@ember/utils';
+import { getOwner } from '@ember/application';
 
 export default Service.extend({
+  isFastBoot: computed(function() {
+    const fastboot = getOwner(this).lookup('service:fastboot');
+    return fastboot ? fastboot.get('isFastBoot') : false;
+  }),
+
   scrollElement: 'window',
 
   init(...args) {
@@ -26,6 +30,10 @@ export default Service.extend({
       x = window.scrollX;
       y = window.scrollY;
     } else if ('#' === scrollElement.charAt(0)) {
+      if (get(this, 'isFastBoot')) {
+        return;
+      }
+
       let element = document.getElementById(scrollElement.substring(1));
 
       if (element) {

tests/unit/services/router-scroll-test.js

@@ -3,13 +3,26 @@ import { moduleFor, test } from 'ember-qunit';
 
 moduleFor('service:router-scroll');
 
-// Replace this with your real tests.
 test('it inits `scrollMap` and `key`', function init(assert) {
   const service = this.subject();
   assert.deepEqual(get(service, 'scrollMap'), {});
   assert.deepEqual(get(service, 'key'), null);
 });
 
+test('it inits `scrollMap` and `key` with scrollElement other than window', function init(assert) {
+  const service = this.subject({ scrollElement: '#other-elem' });
+  assert.deepEqual(get(service, 'scrollMap'), {});
+  assert.deepEqual(get(service, 'key'), null);
+});
+
+test('updating will not set `scrollMap` to the current scroll position if `key` is not yet set',
+function scrollMapCurrentPos(assert) {
+  const service = this.subject();
+
+  service.update();
+  assert.deepEqual(get(service, 'scrollMap'), { });
+});
+
 test('updating will set `scrollMap` to the current scroll position', function scrollMap(assert) {
   const service = this.subject();
 
@@ -19,14 +32,46 @@ test('updating will set `scrollMap` to the current scroll position', function sc
   assert.deepEqual(get(service, 'scrollMap'), { 123: expected });
 });
 
-test('updating will not set `scrollMap` to the current scroll position if `key` is not yet set',
+test('updating will not set `scrollMap` if scrollElement is defined',
 function scrollMapCurrentPos(assert) {
-  const service = this.subject();
+  const service = this.subject({ scrollElement: '#other-elem' });
 
   service.update();
+  const expected = { x: 0, y: 0 };
+  assert.deepEqual(get(service, 'position'), expected);
   assert.deepEqual(get(service, 'scrollMap'), { });
 });
 
+test('updating will not set `scrollMap` if scrollElement is defined and in fastboot',
+function scrollMapCurrentPos(assert) {
+  const otherElem = document.createElement('div');
+  otherElem.setAttribute('id', 'other-elem');
+  const testing = document.querySelector('#ember-testing');
+  testing.appendChild(otherElem);
+  const service = this.subject({ scrollElement: '#other-elem', isFastBoot: true });
+  window.history.replaceState({ uuid: '123' }, null);
+
+  let expected = { x: 0, y: 0 };
+  assert.deepEqual(get(service, 'position'), expected, 'position is defaulted');
+  service.update();
+  assert.deepEqual(get(service, 'scrollMap'), { }, 'does not set scrollMap b/c in fastboot');
+});
+
+test('updating will set `scrollMap` if scrollElement is defined',
+function scrollMapCurrentPos(assert) {
+  const otherElem = document.createElement('div');
+  otherElem.setAttribute('id', 'other-elem');
+  const testing = document.querySelector('#ember-testing');
+  testing.appendChild(otherElem);
+  const service = this.subject({ scrollElement: '#other-elem' });
+  window.history.replaceState({ uuid: '123' }, null);
+
+  let expected = { x: 0, y: 0 };
+  assert.deepEqual(get(service, 'position'), expected, 'position is defaulted');
+  service.update();
+  assert.deepEqual(get(service, 'scrollMap'), { '123': expected }, 'sets scrollMap');
+});
+
 test('computing the position for an existing state uuid return the coords',
 function existingUUID(assert) {
   const service = this.subject();