src/third_party/mozjs-45/js/src/tests/test262/ch11/11.6/11.6.1/S11.6.1_A3.1_T1.3.js

// Copyright 2009 the Sputnik authors.  All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/**
 * If Type(Primitive(x)) is not String and Type(Primitive(y)) is not String, then operator x + y returns ToNumber(x) + ToNumber(y)
 *
 * @path ch11/11.6/11.6.1/S11.6.1_A3.1_T1.3.js
 * @description Type(Primitive(x)) and Type(Primitive(y)) vary between Null and Undefined
 */

//CHECK#1
if (isNaN(null + undefined) !== true) {
  $ERROR('#1: null + undefined === Not-a-Number. Actual: ' + (null + undefined));
}

//CHECK#2
if (isNaN(undefined + null) !== true) {
  $ERROR('#2: undefined + null === Not-a-Number. Actual: ' + (undefined + null));
}

//CHECK#3
if (isNaN(undefined + undefined) !== true) {
  $ERROR('#3: undefined + undefined === Not-a-Number. Actual: ' + (undefined + undefined));
}

//CHECK#4
if (null + null !== 0) {
  $ERROR('#4: null + null === 0. Actual: ' + (null + null));
}