v8/test/mjsunit/es6/debug-promises-async-task-event.js

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Flags: --expose-debug-as debug

Debug = debug.Debug;

var base_id = -1;
var exception = null;
var expected = [
  "enqueue #1",
  "willHandle #1",
  "then #1",
  "enqueue #2",
  "didHandle #1",
  "willHandle #2",
  "then #2",
  "enqueue #3",
  "didHandle #2",
  "willHandle #3",
  "didHandle #3"
];

function assertLog(msg) {
  print(msg);
  assertTrue(expected.length > 0);
  assertEquals(expected.shift(), msg);
  if (!expected.length) {
    Debug.setListener(null);
  }
}

function listener(event, exec_state, event_data, data) {
  if (event != Debug.DebugEvent.AsyncTaskEvent) return;
  try {
    if (base_id < 0)
      base_id = event_data.id();
    var id = event_data.id() - base_id + 1;
    assertEquals("Promise.resolve", event_data.name());
    assertLog(event_data.type() + " #" + id);
  } catch (e) {
    print(e + e.stack)
    exception = e;
  }
}

Debug.setListener(listener);

var resolver;
var p = new Promise(function(resolve, reject) {
  resolver = resolve;
});
p.then(function() {
  assertLog("then #1");
}).then(function() {
  assertLog("then #2");
});
resolver();

assertNull(exception);