LayoutTests/ietestcenter/Javascript/TestCases/15.4.4.15-4-7.js

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ES5Harness.registerTest( {
id: "15.4.4.15-4-7",

path: "TestCases/chapter15/15.4/15.4.4/15.4.4.15/15.4.4.15-4-7.js",

description: "Array.prototype.lastIndexOf returns -1 if 'length' is 0 ( length is object overridden with obj w/o valueOf (toString))",

test: function testcase() {
  foo.prototype = new Array(1, 2, 3);
  function foo() {}
  var f = new foo();
  
  var o = { toString: function () { return '0';}};
  f.length = o;
  
  // objects inherit the default valueOf method of the Object object;
  // that simply returns the itself. Since the default valueOf() method
  // does not return a primitive value, ES next tries to convert the object
  // to a number by calling its toString() method and converting the
  // resulting string to a number.
 var i = Array.prototype.lastIndexOf.call({length: { toString: function () { return '0';}}}, 1);
  
  if (i === -1) {
    return true;
  }
 },

precondition: function prereq() {
  return fnExists(Array.prototype.lastIndexOf);
 }
});