michael@0: // Copyright 2012 Mozilla Corporation. All rights reserved.
michael@0: // This code is governed by the BSD license found in the LICENSE file.
michael@0: 
michael@0: /**
michael@0:  * @description Tests that obj meets the requirements for built-in objects
michael@0:  *     defined by the introduction of chapter 15 of the ECMAScript Language Specification.
michael@0:  * @param {Object} obj the object to be tested.
michael@0:  * @param {boolean} isFunction whether the specification describes obj as a function.
michael@0:  * @param {boolean} isConstructor whether the specification describes obj as a constructor.
michael@0:  * @param {String[]} properties an array with the names of the built-in properties of obj,
michael@0:  *     excluding length, prototype, or properties with non-default attributes.
michael@0:  * @param {number} length for functions only: the length specified for the function
michael@0:  *     or derived from the argument list.
michael@0:  * @author Norbert Lindenberg
michael@0:  */
michael@0: 
michael@0: function testBuiltInObject(obj, isFunction, isConstructor, properties, length) {
michael@0: 
michael@0:     if (obj === undefined) {
michael@0:         $ERROR("Object being tested is undefined.");
michael@0:     }
michael@0: 
michael@0:     var objString = Object.prototype.toString.call(obj);
michael@0:     if (isFunction) {
michael@0:         if (objString !== "[object Function]") {
michael@0:             $ERROR("The [[Class]] internal property of a built-in function must be " +
michael@0:                     "\"Function\", but toString() returns " + objString);
michael@0:         }
michael@0:     } else {
michael@0:         if (objString !== "[object Object]") {
michael@0:             $ERROR("The [[Class]] internal property of a built-in non-function object must be " +
michael@0:                     "\"Object\", but toString() returns " + objString);
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     if (!Object.isExtensible(obj)) {
michael@0:         $ERROR("Built-in objects must be extensible.");
michael@0:     }
michael@0: 
michael@0:     if (isFunction && Object.getPrototypeOf(obj) !== Function.prototype) {
michael@0:         $ERROR("Built-in functions must have Function.prototype as their prototype.");
michael@0:     }
michael@0: 
michael@0:     if (isConstructor && Object.getPrototypeOf(obj.prototype) !== Object.prototype) {
michael@0:         $ERROR("Built-in prototype objects must have Object.prototype as their prototype.");
michael@0:     }
michael@0: 
michael@0:     // verification of the absence of the [[Construct]] internal property has
michael@0:     // been moved to the end of the test
michael@0:     
michael@0:     // verification of the absence of the prototype property has
michael@0:     // been moved to the end of the test
michael@0: 
michael@0:     if (isFunction) {
michael@0:         
michael@0:         if (typeof obj.length !== "number" || obj.length !== Math.floor(obj.length)) {
michael@0:             $ERROR("Built-in functions must have a length property with an integer value.");
michael@0:         }
michael@0:     
michael@0:         if (obj.length !== length) {
michael@0:             $ERROR("Function's length property doesn't have specified value; expected " +
michael@0:                 length + ", got " + obj.length + ".");
michael@0:         }
michael@0: 
michael@0:         var desc = Object.getOwnPropertyDescriptor(obj, "length");
michael@0:         if (desc.writable) {
michael@0:             $ERROR("The length property of a built-in function must not be writable.");
michael@0:         }
michael@0:         if (desc.enumerable) {
michael@0:             $ERROR("The length property of a built-in function must not be enumerable.");
michael@0:         }
michael@0:         if (desc.configurable) {
michael@0:             $ERROR("The length property of a built-in function must not be configurable.");
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     properties.forEach(function(prop) {
michael@0:         var desc = Object.getOwnPropertyDescriptor(obj, prop);
michael@0:         if (desc === undefined) {
michael@0:             $ERROR("Missing property " + prop + ".");
michael@0:         }
michael@0:         // accessor properties don't have writable attribute
michael@0:         if (desc.hasOwnProperty("writable") && !desc.writable) {
michael@0:             $ERROR("The " + prop + " property of this built-in function must be writable.");
michael@0:         }
michael@0:         if (desc.enumerable) {
michael@0:             $ERROR("The " + prop + " property of this built-in function must not be enumerable.");
michael@0:         }
michael@0:         if (!desc.configurable) {
michael@0:             $ERROR("The " + prop + " property of this built-in function must be configurable.");
michael@0:         }
michael@0:     });
michael@0: 
michael@0:     // The remaining sections have been moved to the end of the test because
michael@0:     // unbound non-constructor functions written in JavaScript cannot possibly
michael@0:     // pass them, and we still want to test JavaScript implementations as much
michael@0:     // as possible.
michael@0:     
michael@0:     var exception;
michael@0:     if (isFunction && !isConstructor) {
michael@0:         // this is not a complete test for the presence of [[Construct]]:
michael@0:         // if it's absent, the exception must be thrown, but it may also
michael@0:         // be thrown if it's present and just has preconditions related to
michael@0:         // arguments or the this value that this statement doesn't meet.
michael@0:         try {
michael@0:             /*jshint newcap:false*/
michael@0:             var instance = new obj();
michael@0:         } catch (e) {
michael@0:             exception = e;
michael@0:         }
michael@0:         if (exception === undefined || exception.name !== "TypeError") {
michael@0:             $ERROR("Built-in functions that aren't constructors must throw TypeError when " +
michael@0:                 "used in a \"new\" statement.");
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     if (isFunction && !isConstructor && obj.hasOwnProperty("prototype")) {
michael@0:         $ERROR("Built-in functions that aren't constructors must not have a prototype property.");
michael@0:     }
michael@0: 
michael@0:     // passed the complete test!
michael@0:     return true;
michael@0: }
michael@0: