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// |reftest| async
// Copyright 2018 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
author: Maya Lekova <mslekova@chromium.org>
esid: await
description: >
for-await-of iteration and builtin Promises are properly interleaved,
meaning await in for-of loop takes only 1 tick on the microtask queue.
flags: [async]
features: [async-functions, async-iteration, generators]
includes: [compareArray.js]
---*/
const actual = [];
const expected = [
'Promise: 6',
'Promise: 5',
'Await: 3',
'Promise: 4',
'Promise: 3',
'Await: 2',
'Promise: 2',
'Promise: 1',
'Await: 1',
'Promise: 0'
];
const iterations = 3;
async function* naturalNumbers(start) {
let current = start;
while (current > 0) {
yield Promise.resolve(current--);
}
}
async function trigger() {
for await (const num of naturalNumbers(iterations)) {
actual.push('Await: ' + num);
}
}
async function checkAssertions() {
assert.compareArray(actual, expected,
'Async/await and promises should be interleaved');
}
function countdown(counter) {
actual.push('Promise: ' + counter);
if (counter > 0) {
return Promise.resolve(counter - 1).then(countdown);
} else {
checkAssertions().then($DONE, $DONE);
}
}
trigger();
countdown(iterations * 2);
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