tests/language/async_star_pause_test.dart

// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

library async_star_pause_test;

import "package:unittest/unittest.dart";
import "dart:async";

main() {
  test("await for pauses stream during body", () async {
    // Assumes await-for uses streamIterator.
    var log = [];
    var s = () async* {
      for (int i = 0; i < 3; i++) {
        log.add("$i-");
        yield i;
        // Should pause here until next iteration of await-for loop.
        log.add("$i+");
      }
    }();
    await for (var i in s) {
      log.add("$i?");
      await nextMicrotask();
      log.add("$i!");
    }
    expect(log, ["0-", "0?", "0!", "0+",
                 "1-", "1?", "1!", "1+",
                 "2-", "2?", "2!", "2+"]);
  });
}
Future nextMicrotask() => new Future.microtask((){});