LibTest/async/Future/Future.sync_A01_t04.dart

// Copyright (c) 2011, 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.sync(dynamic computation())
/// Creates a future containing the result of immediately calling computation.
/// If calling computation throws, the returned future is completed with the
/// error.
/// If calling computation returns a Future, completion of the created future
/// will wait until the returned future completes, and will then complete with
/// the same result.
/// If calling computation returns a non-future value, the returned future is
/// completed with that value.
/// @description Checks that if computation() returns a future, the returned
/// future is completed first and then created future is completed with the same
/// result.
/// @author ilya

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

main() {
  var value = [1, 2, 3];
  var completer = new Completer();
  Future future = new Future.sync(() => completer.future);

  var completer2 = new Completer();
  Future future2 = new Future.sync(() => completer2.future);

  asyncMultiStart(2);

  future
    .then((x) {
      Expect.isTrue(completer.isCompleted);
      Expect.identical(value, x);
      asyncEnd();
    });

  future2.then(
    (_) {
      Expect.fail("Created future should complete with error");
    },
    onError: (x) {
      Expect.isTrue(completer2.isCompleted);
      Expect.identical(value, x);
      asyncEnd();
    }
  );

  completer.complete(value);
  completer2.completeError(value);
}