unit testing - How can I "sleep" a Dart program

Question

I like to simulate an asynchronous web service call in my Dart application for testing. To simulate the randomness of these mock calls responding (possibly out of order) I'd like to program my mocks to wait (sleep) for a certain period of time before returning the 'Future'.

How can I do this?

Answer 1

2019 edition:

In Async Code

await Future.delayed(Duration(seconds: 1));

In Sync Code

import 'dart:io';

sleep(Duration(seconds:1));

Note: This blocks the entire process (isolate), so other async functions will not be processed. It's also not available on the web because Javascript is really async-only.