Update method, add tests and correct documentation

Will now works as I expected before :)

@@ -450,7 +450,7 @@ Asserts that the provided input is of the given type::
 ``assertInstanceOf()``
 -------------------------------------------------------------------------------
 
-**Signature:** ``assertInstanceOf(mixed input, function constructor[, String message])``
+**Signature:** ``assertInstanceOf(mixed input, String className[, String message])``
 
 Asserts that the provided input is of the given className::
     
@@ -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, "Okay, daisy is a cow.");
-        test.assertInstanceOf(daisy, Casper, "Moo is not Boo");
+        test.assertInstanceOf(daisy, "Cow", "Ok, daisy is a cow.");
+        test.assertInstanceOf(["moo", "boo"], "Array", "We can test for arrays too!");
         test.done();
     });
 

@@ -843,22 +843,21 @@ Tester.prototype.assertType = function assertType(subject, type, message) {
  * Asserts that the provided subject is of the given class name.
  *
  * @param  mixed   subject          The value to test
- * @param  function  constructor    The object constructor
+ * @param  string  className        The className
  * @param  String  message          Test description
  * @return Object                   An assertion result object
  */
-Tester.prototype.assertInstanceOf = function assertInstanceOf(subject, constructor, message) {
+Tester.prototype.assertInstanceOf = function assertInstanceOf(subject, className, message) {
     "use strict";
     if (utils.betterTypeOf(constructor) !== "function") {
-        throw new CasperError('Invalid constructor.');
+        throw new CasperError('Subject is null or undefined.');
     }
-    return this.assert(subject instanceof constructor, message, {
+    return this.assert(utils.equals(subject.constructor.name, className), message, {
         type: "assertInstanceOf",
         standard: f('Subject is an instance of: "%s"', constructor.name),
         values: {
             subject: subject,
             constructor: constructor.name,
-            actual: actual
         }
     });
 };

@@ -2,7 +2,7 @@
 /*jshint strict:false, maxstatements:99*/
 var fs = require('fs');
 
-casper.test.begin('Common assertions tests', 46, function(test) {
+casper.test.begin('Common assertions tests', 50, 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]');
@@ -60,9 +60,15 @@ casper.test.begin('Common assertions tests', 46, 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 constructor and an object
-        function Cow(){} var daisy = new Cow();
-        test.assertInstanceOf(daisy, Cow, "Tester.assertInstanceOf() works as expected");
+        // We need two objects to test inheritance case
+        function Cow(){}; function SuperCow(){}; SuperCow.prototype = new Cow;
+        var daisy = new Cow(); var superCowie = new SuperCow();
+        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(superCowie, "SuperCow", "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');