This is my gist to show how they work

filename.js

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

/*---
info: >
    The elements of the array are rearranged so as to reverse their order.
    The object is returned as the result of the call
esid: sec-array.prototype.reverse
es5id: 15.4.4.8_A1_T1
description: Checking case when reverse is given no arguments or one argument
---*/

//CHECK#1
var x = [];
var reverse = x.reverse();
if (reverse !== x) {
  $ERROR('#1: x = []; x.reverse() === x. Actual: ' + (reverse));
}

//CHECK#2
x = [];
x[0] = 1;
var reverse = x.reverse();
if (reverse !== x) {
  $ERROR('#2: x = []; x[0] = 1; x.reverse() === x. Actual: ' + (reverse));
}

//CHECK#3
x = new Array(1,2);
var reverse = x.reverse();
if (reverse !== x) {
  $ERROR('#3: x = new Array(1,2); x.reverse() === x. Actual: ' + (reverse));
}

//CHECK#4
if (x[0] !== 2) {
  $ERROR('#4: x = new Array(1,2); x.reverse(); x[0] === 2. Actual: ' + (x[0]));
}

//CHECK#5
if (x[1] !== 1) {
  $ERROR('#5: x = new Array(1,2); x.reverse(); x[1] === 1. Actual: ' + (x[1]));
}

//CHECK#6
if (x.length !== 2) {
  $ERROR('#6: x = new Array(1,2); x.reverse(); x.length === 2. Actual: ' + (x.length));
}