title: How to assert the activity is finished with espresso
body: <p>I want to assert the activity is finished after clicking a button.
  eg: if the user clicked button with id R.id.finish, then the activity is finished.</p>
  <p>I'm trying to look up apis with ActivitySenerio and Espresso, but none of these helps.</p>
  <p>Ref:</p>
  <ul>
  <li><a href="https://developer.android.google.cn/training/testing/espresso" rel="nofollow noreferrer">https://developer.android.google.cn/training/testing/espresso</a></li>
  </ul>