title: Angular 5 change detection on mutable objects
body: <p>I know this is a frequent question, but this is more related to Angular 5.
  From what I remember this used to work in Angular 2, unless I specify</p>
  
  <pre><code>changeDetection: ChangeDetectionStrategy.OnPush
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code>  addFruit(food) {
      // this is not working
      this.fruits.push(food);
  
      // this works
      // this.fruits = [...this.fruits, food];
    }
  </code></pre>
  
  <p>Did something changed in Angular 5+ that the first method is no longer working?</p>
  
  <p>Working example: <a href="https://stackblitz.com/edit/angular-ch-detec?file=app%2Fapp.component.ts" rel="nofollow noreferrer">https://stackblitz.com/edit/angular-ch-detec?file=app%2Fapp.component.ts</a></p>