LibTest/async/Future/doWhile_A01_t01.dart

// Copyright (c) 2016, 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.

/// @assertion  Future doWhile(FutureOr<bool> f())
///    Performs an async operation repeatedly until it returns false.
///    The function f is called repeatedly while it returns either the bool
/// value true or a Future which completes with the value true.
///    If a call to f returns false or a Future that completes to false,
/// iteration ends and the future returned by doWhile is completed.
///
/// @description Checks that doWhile runs f repeatedly, if f returns true, and
/// returns a Future that completes once f returns false.
/// @author ngl@unipro.ru

import "dart:async";
import "../../../Utils/expect.dart";

const int N = 3;

main() {
  int num = 0;

  FutureOr<bool> f() {
    num++;
    return num < N;
  }

  asyncStart();
  Future.doWhile(f).then(
    (_) {
      Expect.equals(N, num);
      asyncEnd();
    }
  );
}