Introduced Tester.assertInstanceOf method, refs #602

- add utils.betterInstanceOf
- add 12 tests
- add documentation

@@ -450,9 +450,9 @@ Asserts that the provided input is of the given type::
 ``assertInstanceOf()``
 -------------------------------------------------------------------------------
 
-**Signature:** ``assertInstanceOf(mixed input, String className[, String message])``
+**Signature:** ``assertInstanceOf(mixed input, function constructor[, String message])``
 
-Asserts that the provided input is of the given className::
+Asserts that the provided input is of the given constructor::
     
     function Cow() {
         this.moo = function moo() {
@@ -461,8 +461,8 @@ Asserts that the provided input is of the given className::
     } 
     casper.test.begin('assertInstanceOf() tests', 2, function suite(test) {
         var daisy = new Cow();
-        test.assertInstanceOf(daisy, "Cow", "Ok, daisy is a cow.");
-        test.assertInstanceOf(["moo", "boo"], "Array", "We can test for arrays too!");
+        test.assertInstanceOf(daisy, Cow, "Ok, daisy is a cow.");
+        test.assertInstanceOf(["moo", "boo"], Array, "We can test for arrays too!");
         test.done();
     });
 

@@ -840,24 +840,24 @@ Tester.prototype.assertType = function assertType(subject, type, message) {
 };
 
 /**
- * Asserts that the provided subject is of the given class name.
+ * Asserts that the provided subject is of the given class.
  *
- * @param  mixed   subject          The value to test
- * @param  string  className        The className
- * @param  String  message          Test description
- * @return Object                   An assertion result object
+ * @param  mixed   subject       The value to test
+ * @param  function constructor  The javascript type name
+ * @param  String  message       Test description
+ * @return Object                An assertion result object
  */
-Tester.prototype.assertInstanceOf = function assertInstanceOf(subject, className, message) {
+Tester.prototype.assertInstanceOf = function assertInstanceOf(subject, constructor, message) {
     "use strict";
-    if (utils.betterTypeOf(subject.constructor) !== "function") {
+    if (utils.betterTypeOf(constructor) !== "function") {
         throw new CasperError('Subject is null or undefined.');
     }
-    return this.assert(utils.equals(subject.constructor.name, className), message, {
+    return this.assert(utils.betterInstanceOf(subject, constructor), message, {
         type: "assertInstanceOf",
-        standard: f('Subject is an instance of: "%s"', subject.constructor.name),
+        standard: f('Subject type is: "%s"', constructor),
         values: {
             subject: subject,
-            className: className,
+            className: constructor.name,
         }
     });
 };

@@ -71,6 +71,33 @@ function betterTypeOf(input) {
 exports.betterTypeOf = betterTypeOf;
 
 /**
+ * Provides a better instanceof operator equivalent, able to retrieve the uninstantiated string
+ * or inheritance cases.
+ *
+ * @param  mixed  input
+ * @param  function constructor
+ * @return String
+ * @see    https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Details_of_the_Object_Model
+ */
+function betterInstanceOf(input, constructor) {
+    "use strict";
+    while (input !== null) {
+      if (input === constructor.prototype) {
+        return true;
+      }
+      if (typeof input === 'xml') {
+        return constructor.prototype === document.prototype;
+      }
+      if (typeof input === 'undefined') {
+        return false;
+      }
+      input = input.__proto__;
+   }
+   return false;
+}
+exports.betterInstanceOf = betterInstanceOf;
+
+/**
  * Cleans a passed URL.
  *
  * @param  String  url An HTTP URL

@@ -2,7 +2,7 @@
 /*jshint strict:false, maxstatements:99*/
 var fs = require('fs');
 
-casper.test.begin('Common assertions tests', 50, function(test) {
+casper.test.begin('Common assertions tests', 46, function(test) {
     casper.start('tests/site/index.html', function() {
         test.assertTextExists('form', 'Tester.assertTextExists() checks that page body contains text');
         test.assertTextExist('form', 'Tester.assertTextExist() checks that page body contains text [alias]');
@@ -60,13 +60,7 @@ casper.test.begin('Common assertions tests', 50, function(test) {
         test.assertTitleMatch(/test index/, 'Tester.assertTitleMatch() works as expected');
         test.assertTitleMatches(/test index/, 'Tester.assertTitleMatches() works as expected [alias]');
         test.assertType("plop", "string", "Tester.assertType() works as expected");
-        // we need a class and an instance of this class
-        function Cow(){} var daisy = new Cow();
-        test.assertInstanceOf(12, "Number", "Tester.assertInstanceOf() works as expected");
-        test.assertInstanceOf("Boo", "String", "Tester.assertInstanceOf() works as expected");
-        test.assertInstanceOf(["moo", "bar"], "Array", "Tester.assertInstanceOf() works as expected")
-        test.assertInstanceOf(true, "Boolean", "Test.assertInstanceOf() works as expected");
-        test.assertInstanceOf(daisy, "Cow", "Tester.assertInstanceOf() works as expected");
+        test.assertInstanceOf("plop", String, "Tester.assertInstanceOf() works as expected");
         test.assertUrlMatch(/index\.html$/, "Tester.assertUrlMatch() works as expected");
         test.assertUrlMatches(/index\.html$/, "Tester.assertUrlMatches() works as expected [alias]");
         test.assertVisible('img', 'Tester.assertVisible() works as expected');

@@ -24,6 +24,32 @@ casper.test.begin('utils.betterTypeOf() tests', 10,  function(test) {
     test.done();
 });
 
+casper.test.begin('utils.betterInstanceOf() tests', 12,  function(test) {
+    // need two objects to test inheritance
+    function Cow(){} var daisy = new Cow();
+    function SuperCow(){} SuperCow.prototype = new Cow(); var superDaisy = new SuperCow();
+    var date = new Date(); var regex = new RegExp();
+    var testCases = [
+        {subject: 1, fn: Number, expected: true},
+        {subject: '1', fn: String, expected: true},
+        {subject: {}, fn: Object, expected: true},
+        {subject: [], fn: Array, expected: true},
+        {subject: undefined, fn: Array, expected: false},
+        {subject: null, fn: Array, expected: false},
+        {subject: function(){}, fn: Function, expected: true},
+        {subject: date, fn: Date, expected: true},
+        {subject: regex, fn: RegExp, expected: true},
+        {subject: daisy, fn: Cow, expected: true},
+        {subject: superDaisy, fn: SuperCow, expected: true},
+        {subject: superDaisy, fn: Cow, expected: true}
+    ];
+    testCases.forEach(function(testCase) {
+        test.assertEquals(utils.betterInstanceOf(testCase.subject, testCase.fn), testCase.expected,
+            utils.format('betterInstanceOf() detects expected constructor "%s"', testCase.fn.name));
+    });
+    test.done();
+});
+
 casper.test.begin('utils.cleanUrl() tests', 11, function(test) {
     var testCases = {
         'http://google.com/': 'http://google.com/',