Added first set of tests.

Cakefile

@@ -7,9 +7,9 @@ class BuildUtils
     console.log string.as_console_message()
 
   error_handler: (err, stdout, stderr) ->
-    throw err if err
     console.log stdout if stdout
     console.log stderr if stderr
+    throw err if err
 
   process: (content, callback) ->
     self = @
@@ -35,7 +35,7 @@ class BuildUtils
       content = new Array()
 
       for file, index in files then do (file, index) ->
-        if file.indexOf('.') isnt 0
+        unless file.indexOf('.') is 0
           fs.readFile "./src/#{file}", 'utf8', (err, fileContent) ->
             self.error_handler err
             content[content.length] = fileContent
@@ -59,3 +59,9 @@ task 'minify', 'Minify the generate jquery.rambling.slider files', ->
     (err, stdout, stderr) ->
       utils.error_handler err, stdout, stderr
       utils.log 'Done'
+
+task 'spec', 'Run all specs', ->
+  utils.log 'Running specs...'
+  exec 'jasmine-node --coffee spec/', (err, stdout, stderr) ->
+    utils.error_handler err, stdout, stderr
+    utils.log 'Done' unless err

README.markdown

@@ -42,6 +42,20 @@ If you want to minify the existing js:
 
 <code>cake minify</code>
 
+### Unit testing
+
+If you want to run the unit tests, you'll need to install <code>jasmine-node</code>. It's easily installed with:
+
+<code>npm install -g jasmine-node</code>
+
+To run all the tests, you can run:
+
+<code>jasmine-node --coffee spec/</code>
+
+Or simply:
+
+<code>cake spec</code>
+
 ## License and copyright
 
 Copyright (c) 2011 Edgar Gonzalez

spec/array_extensions.spec.coffee

@@ -0,0 +1,18 @@
+require '../src/array_extensions'
+
+describe 'Array Extensions', ->
+  describe 'when shuffling an array', ->
+    original_array = null
+    first_copy = null
+    second_copy = null
+
+    beforeEach ->
+      original_array = [1..100]
+      first_copy = original_array
+      second_copy = original_array.shuffle()
+
+    it 'should return a copy with shifted the positions', ->
+      expect(second_copy).not.toEqual original_array
+
+    it 'should let the original array untouched', ->
+      expect(first_copy).toEqual original_array

src/array_extensions.coffee

@@ -1,7 +1,9 @@
 Array::shuffle = ->
+  new_array = []
   for i in [@length..1]
+    new_array[i] = @[i]
     j = parseInt(Math.random() * i)
     x = @[--i]
-    @[i] = @[j]
-    @[j] = x
-  @
+    new_array[i] = @[j]
+    new_array[j] = x
+  new_array