async-await-interleaved.js 2.45 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
// Copyright 2018 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

28 29
// Flags: --ignore-unhandled-promises

30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
// Check for correct interleaving of Promises and async/await
(function () {
  const iterations = 10;
  let promiseCounter = iterations;
  let awaitCounter = 0;

  async function check(v) {
    awaitCounter = v;
    // The following checks ensure that "await" takes 3 ticks on the
    // microtask queue. Note: this will change in the future
    if (awaitCounter === 0) {
      assertEquals(iterations, promiseCounter);
    } else if (awaitCounter <= Math.floor(iterations / 3)) {
      assertEquals(iterations - awaitCounter * 3, promiseCounter);
    } else {
      assertEquals(0, promiseCounter);
    }
  }

  async function f() {
    for (let i = 0; i < iterations; i++) {
      await check(i);
    }
    return 0;
  }

  function countdown(v) {
    promiseCounter = v;
    if (v > 0) Promise.resolve(v - 1).then(countdown);
  }

  countdown(iterations);
  f();
})();