Add mixin unit test for return-to (#891)

- Add mixin unit test for return-to

tests/unit/mixins/return-to-test.js

@@ -0,0 +1,33 @@
+import ReturnTo from 'hospitalrun/mixins/return-to';
+import { moduleFor, test } from 'ember-qunit';
+import Ember from 'ember';
+import DS from 'ember-data';
+
+moduleFor('mixin:return-to', 'Unit | Mixin | return-to', {
+  subject(attrs) {
+    return Ember.run(() => {
+      let Test = DS.Model.extend(ReturnTo);
+      this.register('model:test', Test);
+      return this.store().createRecord('test', attrs);
+    });
+  },
+  store() {
+    return this.container.lookup('service:store');
+  }
+});
+
+test('cancelAction', function(assert) {
+  let returnTo = this.subject({
+    model: {
+      returnTo: 'test'
+    }
+  });
+
+  assert.strictEqual(returnTo.get('cancelAction'), 'returnTo');
+});
+
+test('cancelAction allItems', function(assert) {
+  let returnTo = this.subject();
+
+  assert.strictEqual(returnTo.get('cancelAction'), 'allItems');
+});