JSTests/test262/test/language/expressions/compound-assignment/S11.13.2_A4.5_T2.3.js

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

/*---
info: The production x -= y is the same as x = x - y
es5id: 11.13.2_A4.5_T2.3
description: >
    Type(x) is different from Type(y) and both types vary between
    Number (primitive or object) and Null
---*/

var x;

//CHECK#1
x = 1;
x -= null;
if (x !== 1) {
  throw new Test262Error('#1: x = 1; x -= null; x === 1. Actual: ' + (x));
}

//CHECK#2
x = null;
x -= 1;
if (x !== -1) {
  throw new Test262Error('#2: x = null; x -= 1; x === -1. Actual: ' + (x));
}

//CHECK#3
x = new Number(1);
x -= null;
if (x !== 1) {
  throw new Test262Error('#3: x = new Number(1); x -= null; x === 1. Actual: ' + (x));
}

//CHECK#4
x = null;
x -= new Number(1);
if (x !== -1) {
  throw new Test262Error('#4: x = null; x -= new Number(1); x === -1. Actual: ' + (x));
}