runUnsynchronized<T> method

Future<T> runUnsynchronized <T>(Future<T> action(), { Duration timeout })

action will be executed with the frame sync mechanism disabled.

By default, Flutter Driver waits until there is no pending frame scheduled in the app under test before executing an action. This mechanism is called "frame sync". It greatly reduces flakiness because Flutter Driver will not execute an action while the app under test is undergoing a transition.

Having said that, sometimes it is necessary to disable the frame sync mechanism (e.g. if there is an ongoing animation in the app, it will never reach a state where there are no pending frames scheduled and the action will time out). For these cases, the sync mechanism can be disabled by wrapping the actions to be performed by this runUnsynchronized method.

With frame sync disabled, its the responsibility of the test author to ensure that no action is performed while the app is undergoing a transition to avoid flakiness.

Implementation 

Future<T> runUnsynchronized<T>(Future<T> action(), { Duration timeout }) async {
  timeout ??= _shortTimeout(timeoutMultiplier);
  await _sendCommand(SetFrameSync(false, timeout: timeout));
  T result;
  try {
    result = await action();
  } finally {
    await _sendCommand(SetFrameSync(true, timeout: timeout));
  }
  return result;
}