JSTests/test262/test/built-ins/Promise/race/invoke-then.js

// Copyright (C) 2015 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
description: >
    Invocation of the instance's `then` method
es6id: 25.4.4.3
info: |
    11. Let result be PerformPromiseRace(iteratorRecord, C, promiseCapability).

    [...]

    25.4.4.3.1 Runtime Semantics: PerformPromiseRace

    1. Repeat
        [...]
        j. Let result be Invoke(nextPromise, "then",
           «promiseCapability.[[Resolve]], promiseCapability.[[Reject]]»).
        k. ReturnIfAbrupt(result).
---*/

var p1 = new Promise(function() {});
var p2 = new Promise(function() {});
var p3 = new Promise(function() {});
var callCount = 0;
var currentThis = p1;
var nextThis = p2;
var afterNextThis = p3;

p1.then = p2.then = p3.then = function(a, b) {
  assert.sameValue(typeof a, 'function', 'type of first argument');
  assert.sameValue(
    a.length,
    1,
    'ES6 25.4.1.3.2: The length property of a promise resolve function is 1.'
  );
  assert.sameValue(typeof b, 'function', 'type of second argument');
  assert.sameValue(
    b.length,
    1,
    'ES6 25.4.1.3.1: The length property of a promise reject function is 1.'
  );
  assert.sameValue(arguments.length, 2, '`then` invoked with two arguments');
  assert.sameValue(this, currentThis, '`this` value');

  currentThis = nextThis;
  nextThis = afterNextThis;
  afterNextThis = null;

  callCount += 1;
};

Promise.race([p1, p2, p3]);

assert.sameValue(callCount, 3, '`then` invoked once for every iterated value');