title: Flutter Tests: Waiting for a certain duration
body: <p>I'm trying to wait for some time after I tested tapping my button to then check the result with <code>expect</code>. I'm using <code>Future.delayed</code> for that. But that doesn't work for me. I'm getting a time out error.</p>
  
  <pre><code>  TimeoutException after 0:00:05.000000: Test timed out after 5 seconds.
  </code></pre>
  
  <p>This is the code I use:</p>
  
  <pre><code>... // other tests
  await tester.tap(find.widgetWithText(GestureDetector, "ref size"));
  await new Future.delayed(new Duration(milliseconds: 50));
  expect(testContainerState.childWidth, 50.0);
  </code></pre>
  
  <p>Does any one have an idea why this (imo) strange behavior occurs?</p>