// |reftest| async // Copyright (C) 2018 Valerie Young. All rights reserved. // This code is governed by the BSD license found in the LICENSE file. /*--- esid: sec-%asyncfromsynciteratorprototype%.throw description: throw() will unwrap a Promise value return by the sync iterator info: | %AsyncFromSyncIteratorPrototype%.throw ( value ) ... 2. Let promiseCapability be ! NewPromiseCapability(%Promise%). ... 5. Let throw be GetMethod(syncIterator, "throw"). ... 17. Let steps be the algorithm steps defined in Async-from-Sync Iterator Value Unwrap Functions. ... 20. Return promiseCapability.[[Promise]]. Async-from-Sync Iterator Value Unwrap Functions An async-from-sync iterator value unwrap function is an anonymous built-in function that is used by methods of %AsyncFromSyncIteratorPrototype% when processing the value field of an IteratorResult object, in order to wait for its value if it is a promise and re-package the result in a new "unwrapped" IteratorResult object. Each async iterator value unwrap function has a [[Done]] internal slot. flags: [async] features: [async-iteration] ---*/ var thrownError = new Error("Don't catch me.") var obj = { [Symbol.iterator]() { return { next() { return { value: 1, done: false }; }, throw() { return { value: Promise.resolve(42), done: true }; } }; } }; async function* asyncg() { return yield* obj; } let iter = asyncg(); iter.next().then(function (result) { iter.throw(thrownError).then( function (result) { assert.sameValue(result.value, 42, "Result.value should be unwrapped, got: " + result.value); iter.next().then(({ done, value }) => { assert.sameValue(done, true, 'the iterator is completed'); assert.sameValue(value, undefined, 'value is undefined'); }).then($DONE, $DONE); } ).catch($DONE); }).catch($DONE);