added hint printing when a possible `casperjs` command call is detected

@@ -15,6 +15,7 @@ XXXX-XX-XX, v1.0.0
 - merged PR [#319](https://github.com/n1k0/casperjs/pull/319), fixed [#209](https://github.com/n1k0/casperjs/issues/209) - test duration has been added to XUnit XML result file.
 - `Casper.userAgent()` does not require the instance to be started anymore
 - dubious tests now have dedicated color & styling
+- added hint printing when a possible `casperjs` command call is detected
 
 2012-12-14, v1.0.0-RC6
 ----------------------

@@ -164,10 +164,21 @@ function patchRequire(require, requireDirs) {
 
 function bootstrap(global) {
     "use strict";
-
     var phantomArgs = require('system').args;
 
     /**
+     * Hooks in default phantomjs error handler to print a hint when a possible
+     * casperjs command misuse is detected.
+     *
+     */
+    phantom.onError = function onPhantomError(msg, trace) {
+        phantom.defaultErrorHandler.apply(phantom, arguments);
+        if (msg.indexOf("ReferenceError: Can't find variable: casper") === 0) {
+            console.error('Hint: you may want to use the `casperjs test` command.');
+        }
+    };
+
+    /**
      * Loads and initialize the CasperJS environment.
      */
     phantom.loadCasper = function loadCasper() {