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/*
* 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 Execution of a statement s of the form yield e; proceeds as
* follows:
* First, the expression e is evaluated to an object o. If the enclosing
* function m is marked async* and the stream u associated with m has been
* paused, then execution of m is suspended until u is resumed or canceled.
* Next, o is added to the iterable or stream associated with the immediately
* enclosing function.
* If the enclosing function m is marked async* and the stream u associated
* with m has been canceled, then let c be the finally clause (17.11) of the
* innermost enclosing try-finally statement, if any. If c is defined, let h be
* the handler induced by c. If h is defined, control is transferred to h. If
* h is undefined, the immediately enclosing function terminates.
* The stream associated with an asynchronous generator could be canceled by
* any code with a reference to that stream at any point where the generator
* was passivated. Such a cancellation constitutes an irretrievable error for
* the generator. At this point, the only plausible action for the generator
* is to clean up after itself via its finally clauses.
* Otherwise, if the enclosing function m is marked async* (9) then the
* enclosing function may suspend.
*
* @description Check that the immediately enclosing function terminates, if
* the stream u associated with m has been canceled and there is no 'finally'
* handler defined.
*
* @author a.semenov@unipro.ru
*/
import 'dart:async';
import '../../../../Utils/expect.dart';
bool generatorAlive = false;
Stream<int> generator() async* {
int i = 0;
while (true) {
generatorAlive = true;
yield i++;
}
}
test() async {
generatorAlive = false;
Stream<int> s = generator();
late StreamSubscription<int> ss;
ss = s.listen(
(int x) async {
if (x == 5) { // let generator to work some time
Expect.equals(true, generatorAlive);
await ss.cancel();
generatorAlive = false;
// verify that generator is not active
for (int i = 0; i < 10; i++) {
Expect.equals(false, generatorAlive);
await new Future.delayed(new Duration(milliseconds: 10));
}
asyncEnd();
}
}
);
}
main() {
asyncStart();
test();
}