JavaScript BDD Framework. DOM independent, async support, 50+ matchers, non-polluting, tiny, highly readable, core jQuery support
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JSpec is a minimalistic JavaScript behavior driven development framework, providing simple installation, extremely low learning curve, absolutely no pollution to core prototypes, async request support, and incredibly sexy syntax, tons of matchers and much more.


  • Highly readable
  • Framework / DOM independent
  • Modular via JSpec Module's and hooks
  • Mock Ajax Requests
  • Rhino support
  • Node.js support
  • Async support
  • Growl (unobtrustive notifications) support
  • Fixture support
  • Ruby JavaScript testing server
  • Nested describes
  • Does not pollute core object prototypes
  • Cascading before/after/before_each/after_each hooks
  • Extremely simple and intuitive matcher declaration
  • Over 45 core matchers
  • Allows parens to be optional when using matchers to increase readability
  • Several helpful reporters (DOM, Terminal, ...)
  • Assertion graphs displaying how many, and which assertions pass or failed
  • Default / customizable evaluation contexts
  • DOM sandbox support
  • Great looking default DOM theme
  • jspec command-line utility for auto-running specs, and initializing project templates
  • Proxy or 'Spy' assertions
  • Method Stubbing
  • Shared behaviors
  • Extend the jspec executable with project / user specific sub-commands.
  • Profiling
  • Interactive Shell
  • Ruby on Rails Integration
  • Install support projects with a single command (jQuery, Rhino, Prototype, Dojo, etc)
  • Tiny (2000-ish LOC)

Companies Using JSpec

To add or request removal from this list please email


Simply download JSpec and include JSpec.css and JSpec.js in your markup. Head over to the downloads section on Github, clone this public repo, or add JSpec as a git submodule with in your project. Alternatively JSpec is also available as a Ruby Gem (though this is not required), which also provides the jspec executable. First install Gemcutter then execute: $ sudo gem install jspec

At which point you may:

$ jspec init myproject

By default, the command above will use absolute path for all JSpec library files. This behavior can be a problem when you're working across different computers or operating systems. You can freeze the library or symlink it.

$ jspec init myproject --freeze
$ jspec init myproject --symlink

JSpec scripts should NOT be referenced via the <script> tag, they should be loaded using the exec method (unless you are using the grammar-less alternative). Below is an example:

  function runSuites() {
    .run({ failuresOnly : true })
<body onLoad="runSuites()">

You may optionally want to use sources in the /pkg directory for your project, since it includes compressed alternatives generated each release.


describe 'ShoppingCart'
    cart = new ShoppingCart
  describe 'addProducts'
    it 'should add several products'
      cart.should.have 2, 'products'

  describe 'checkout'
    it 'should throw an error when checking out with no products'
      -{ cart.clear().checkout() }.should.throw_error EmptyCart

Grammar-less Example

JSpec's grammar is optional, you may also use the equivalent grammar-less alternative below using pure JavaScript (when using the JSpec grammar you may also use grammar-less assertions):

JSpec.describe('ShoppingCart', function(){
    cart = new ShoppingCart

  describe('addProducts', function(){
    it ('should add several products', function(){
      expect(cart).to(have, 2, 'products')

  describe('checkout', function(){
    it ('should throw an error when checking out with no products', function(){
      expect(function(){ cart.clear().checkout() }).to(throw_error, EmptyCart)


The following options may be passed to

  • fixturePath
    • {string} path to fixture directory (DOM, Terminal, Server)
  • failuresOnly
    • {bool} displays only failing specs, making them quick to discover and fix (DOM, Terminal, Server)
  • reportToId
    • {string} an element id to report to when using the DOM reporter (DOM)
  • verbose
    • {bool} verbose server output, defaults to false (Server)



  • equal, be
    • ===
  • be_a, be_an
    • have constructor of x
  • be_an_instance_of
    • instanceof x
  • be_at_least
    • >=
  • be_at_most
    • <=
  • be_null
    • == null
  • be_empty
    • length < 0 or {}
  • be_true
    • == true
  • be_false
    • == false
  • be_type
    • be type of x
  • be_greater_than
    • >
  • be_less_than
    • <
  • be_undefined
    • check if variable passed is undefined
  • throw_error
    • should throw an error, optionally supply the error string or regexp for message comparison
  • have
    • object should have n of property (person.should.have(2, 'pets'))
  • have_at_least
    • object should have at least n of property
  • have_at_most
    • object should have a maximum n of property
  • have_within
    • object should have within n..n of property (person.should.have_within(1..3, 'pets')
  • have_length
    • length of n
  • have_prop
    • object should have property x, optionally supplying an expected value
  • have_property
    • strict version of have_prop
  • be_within
    • checks if n is within the range passed
  • include
    • include substring, array element, or hash key
  • match
    • string should match regexp x
  • respond_to
    • property x should be a function
  • eql
    • matches simple literals (strings, numbers) with == However composites like arrays or 'hashes' are recursively matched, meaning that [1, 2, [3]].should_eql([1, 2, [3]]) will be true.


  • have_tag, have_one
    • have exactly one tag
  • have_tags, have_many
    • have more than one tag
  • have_child
    • have exactly one child
  • have_children
    • have more than one child
  • have_text
    • have plain text
  • have_attr
    • have an attribute, with optional value
  • have_type
  • have_id
  • have_title
  • have_alt
  • have_href
  • have_rel
  • have_rev
  • have_name
  • have_target
  • have_value
  • have_class
  • have_classes
  • be_visible
  • be_hidden
  • be_enabled
  • be_disabled
  • be_selected
  • be_checked

Growl Support

JSpec uses the JavaScript Growl library to provide growl support when using the Rhino JavaScript engine. To enable simply load() jspec.growl.js within spec/rhino.js

Async Support With Mock Timers

The javascript mock timers library is available at although it is already bundled with JSpec at lib/jspec.timers.js

Timers return ids and may be passed to clearInterval(), however they do not execute in threads, they must be manually scheduled and controlled via the tick() function.

}, 400)

tick(200) // Nothing happens
tick(400) // Wahoo!

setInterval() works as expected, although it persists, where as setTimeout() is destroyed after a single call. As conveyed by the last tick() call below, a large increment in milliseconds may cause the callbacks to be called several times to 'catch up'.

progress = ''
var id = setInterval(function(){
  progress += '.'
}, 100)

tick(50),  print(progress) // ''
tick(50),  print(progress) // '.'
tick(100), print(progress) // '..'
tick(100), print(progress) // '...'
tick(300), print(progress) // '......'


tick(800) // Nothing happens

You may also reset at any time using resetTimers()

Proxy Assertions

Proxy or 'Spy' assertions allow you to assert that a method is called n number of times, with x arguments, returning x value. For example:

person = { getPets : function(species){ return ['izzy'] }}
person.should.receive('getPets', 'twice').with_args(an_instance_of(String))and_return(['izzy'])
person.getPets('dog') // This will pass
person.getPets()      // This will fail because we asked an instance of String

This is a useful mechanism for testing the behavior of your object, as well as how other methods may interact with it. Below is another example:

array = ['foo', 'bar']
'array: ' + array // This line causes the spec to pass due to calling toString()

For more examples view spec/spec.matchers.js

Method Stubbing

JSpec currently provides very simple stubbing support shown below:

person = { toString : function(){ return '<Person>' } }
stub(person, 'toString').and_return('Ive been stubbed!')

After each spec all stubs are restored to their original methods so there is no reason to explicitly call destub(). To persist stubs, use a before_each hook:

  stub(someObject, 'method').and_return({ some : thing })

To destub a method simply call destub() at any time:

destub(person, 'toString')

If you would like to whipe an object clear of stubs simply pass it to destub() without an additional method argument:


Alternatively both these utility functions may be called as methods on any object when using the JSpec grammar:

// Converted to stub(someObject, 'method').and_return('whatever')


  • core

    • an_instance_of
      • used in conjunction with the 'receive' matcher
  • jspec.xhr.js

    • mockRequest, mock_request
      • mock a request
    • unmockRequest, unmock_request
      • unmock requests
    • lastRequest, last_request
      • access previous request data
  • jspec.jquery.js

    • sandbox
      • used to generate new DOM sandbox, using jQuery object
    • element
      • same as invoking jQuery, just reads better and no need to worry about $ collisions
    • elements
      • alias of element

Shared Behaviors

JSpec's support for shared behaviors allows multiple suites or describe blocks to share common functionality. For example an Admin, would inherit all specs of User:

describe 'User'
    User = function(name) { = name }
    user = new User('joe')
  it 'should have a name'
    user.should.have_property 'name'
  describe 'Administrator'

      Admin = function(name) { = name }
      Admin.prototype.may = function(perm){ return true }
      user = new Admin('tj')

    it 'should have access to all permissions'
      user.may('edit pages').should.be_true

NOTE: both User and Administrator's before hooks implement the 'user' variable

Mock Ajax Requests

JSpec supports generic Ajax mocking which is usable with any JavaScript framework via jspec.xhr.js. The API is comprised of two functions, mock_request() and unmock_request(). unmock_request() is automatically called after each specification to restore the default functionality of XMLHttpRequest, so it is uncommon to call unmock_request() directly. Below is a jQuery example:

it 'should mock requests'
  mock_request().and_return('{ foo : "bar" }', 'application/json')
  $.getJSON('foo', function(response, statusText){ 'bar'

The mock_request().and_return signature is as follows:

mock_request().and_return(<data>, [content-type], [response-status-code], [headers-hash])

At the moment mock_request() itself does not accept any arguments, however in the future this will be used to target specific uris for mocking.

NOTE: works with Rhino as well


Currently the following hooks are supported, and may be utilized any number of times as they are simply pushed to a stack. So for instance you may have two before_each blocks within the same scope, they will both run, but this can help keep your specs readable.

  • before
    • run once before the suite is executed
  • after
    • run once after the suite is executed
  • before_each
    • run before each specification
  • after_each
    • run after each specification

Custom Contexts

Custom contexts can be applied to supply helper methods or properties to all subsequent bodies (other hooks, or specs).

Keep in mind that when replacing the default context you will loose functionality provided by it, unless you manually merge it with your custom context.

To reset the context simply assign null to obtain the original context.

  JSpec.context = { foo : 'bar' }

  JSpec.context = null

it 'will work ;)'
  foo.should_equal 'bar'

Async Support

Currently only jspec.jquery.js supports async requests. JSpec uses jQuery.ajaxSetup and sets all requests to sync, which preserves execution order, and reports correctly.

it 'should load mah cookies (textfile)'
  $.post('async', function(text){
    text.should_eql 'cookies!'

Grammer Pre-processor

The pre-processing capability of JSpec is extremely powerful. Your JavaScript code is not necessarily what it seems. For example when you seemingly invoke a object's prototype like below:

'foobar'.should.include 'bar'

First parens are added:


Secondly the matcher invocation is converted to a non-polluting match() call:

expect('foobar').to(include, 'bar')

This also means instead of:

var object = { foo : 'bar' }
object.should.include 'foo'

We can do:

{ foo : 'bar' }.should.include 'foo'

Closure Literal

These are equivalent:

-{ throw 'test' }.should.throw_error
function() { throw 'test' }.should.throw_error

Inclusive Range Literal

The following expands to the array of [1,2,3,4,5]

n.should.be_within 1..5


Any text placed after END is considered irrelevant and is striped out before evaluation. This is sometimes useful for document or code reference while writing specs.

For example when writting regression specs it is sometimes useful to paste the issue ticket's comment(s) below this area for reference.


To change a reporter simply alter the options hash like below, assigning a new constructor, or pass it within the hash to run():

JSpec.options.reporter = JSpec.reporters.Terminal


.run({ reporter: JSpec.reporters.Terminal })


The fixture() utility function may be used in order to load arbitrary file contents for use with your specifications. JSpec will resolve fixture('data') in the following manor:

  • /data
  • /data.html

In order for the fixture() utility to function you must pass the fixturePath option to which provides JSpec with the fixture directory.

Testing DOM Elements

When using jQuery testing DOM elements is very easy. Many may think they require specific sandbox divs in their html, however you do not. Using the fixture support mentioned above you may simply load some HTML, and use the elements() utility which is an alias of jQuery:

describe 'JSpec DOM testing'
  describe 'is so easy'
      list = elements(fixture('users-list'))
      // or list = jQuery(fixture('users-list'))
      // or list = $(fixture('users-list'))
    it 'should have users'
      list.should.have_tag 'ul'

You may also use simple strings, since jQuery's constructor will convert them to DOM elements:

describe 'Something'
    html = elements('<p>Foo</p>')
    // or html = $('<p>Foo</p>') ...
  it 'should do something'
    html.should.have_text 'Foo'

Custom Matchers

First lets create a simple equality matcher. In the case below JSpec is smart enough to realize this is simply a binary operator, and simply transforms this into actual === expected

  equal : '==='

To alias a method to keep your specs readable you may alias them like below:

  be : 'alias equal'

'foo'.should.equal 'foo' true

Matchers with string bodies implicitly return the expression value. The expanded version of the equal matcher would then be:

  equal : 'actual === expected'

Large matchers or those which require several parameters may wish to utilize the hash method:

  equal : { match : function(actual, expected){
    return actual === expected

To keep JSpec tiny, JSpec will default to generating failure messages for you, how ever this can be explicitly defined:

  equal : { 
    match : function(actual, expected){
      return actual === expected
    message : function(actual, expected, negate) {
      return 'a message here'

When defining matchers that are extremely similar in functionality, however require different names, you may use a prefixed list of words like below which defines be_disabled, be_selected, be_checked, and have_type, have_id, etc. Each function must return the matcher body which will be used.

  'be disabled selected checked' : function(attr) {
    return 'jQuery(actual).attr("' + attr + '")'

  'have type id title alt href src sel rev name target' : function(attr) {
    return function(actual, value) {
      return value ? jQuery(actual).attr(attr) ## value:

Extending Or Hooking Into JSpec

JSpec provides a hook architecture for extending or analyzing various points in its execution, through the use of modules. For a module example view lib/jspec.jquery.js.

The following methods or properties are utilized by JSpec:

  • name : module name string
  • init : called to initialize a module
  • reporters : hash of reporters merged with JSpec.reporters
  • utilities : hash of utility functions merged with JSpec.defaultContext
  • matchers : hash of matchers merged with JSpec's core matchers via JSpec.addMatchers()
  • DSLs : hash of DSL methods; for example DSLs.snake contains before_each, after_each, etc. Where as DSLs.camel may contain beforeEach, afterEach, etc.

Below is a list of hooks, descriptions, and valid return values which may simply be implemented as module methods. beforeSuite, afterSuite, beforeSpec, and afterSpec have lower precedence than before_each, after_each etc within the specs themselves, allowing them to override or undo anything that has been done by a Module.

  • running(options) : started running JSpec with the options passed : returning 'stop' will halt running
  • loading(file) : loading a file : returning 'stop' will prevent loading
  • executing(file) : executing a file : returning 'stop' will prevent execution
  • posting(data, url) : posting data to a url : returning 'stop' will prevent request
  • preprocessing(input) : before input string is preprocessed : return input string for next hook to preprocess
  • stubbing(object, method, result) : called when stubbing an object's method, and return value (result). : (no return value)
  • requiring(dependency, message) : requiring a dependency : (no return value)
  • beforeAssertion(assertion) : before an assertion has been made : (no return value)
  • afterAssertion(assertion) : after an assertion has been made : (no return value)
  • addingMatcher(name, body) : unprocessed matcher name and body : (no return value)
  • addingSuite(suite) : adding Suite instance to JSpec : (no return value)
  • beforeSuite(suite) : before running of suite (describe block) : (no return value)
  • afterSuite(suite) : after running of suite (describe block) : (no return value)
  • beforeSpec(spec) : before running of spec (it block) : (no return value)
  • afterSpec(spec) : after running of spec (it block) : (no return value)
  • reporting(options) : called before reporting : (no return value)
  • evaluatingBody(dsl, matchers, context, contents) : evaluating body contents, with the given context, matchers and dsl. : (no return value)

For example you may wish to proxy files which are being executed, simply implement the executing method like below. This example will stop execution of any file matching /matchers/.

MyModule = {
  executing : function(file) {
    if (file.match(/matchers/))
      return 'stop'

Immutable values may also be passed to hooks using hookImmutable() internally. This allows for simple numbers, strings, etc to be utilized or altered within a hook implementation. Below is an example module which adds functionality to the JSpec grammar by converting SomeObject.stub('method') to stub(SomeObject, 'method'):

  preprocessing : function(input) {
    return input.replace(/(\w+)\.(stub|destub)\((.*?)\)$/gm, '$2($1, $3)')

JSpec Command-line Utility

When installed as a Ruby Gem, the jspec executable will become available, allowing you to initialize project templates quickly, as well as auto-testing specifications when a file is altered.

Initialize JSpec-driven project template in directory myproject: $ jspec init myproject

Once within 'myproject' start testing by executing: $ jspec

For additional usage execute: $ jspec help

Or for specific usage: $ jspec help run

Extending JSpec's Executable

Both project specific, and user specific sub-commands may be used to extend those already provided by jspec. For example create the following in spec/commands/example_command.rb which are loaded when jspec is executed.

command :example do |c|
  c.syntax = 'jspec example [options]'
  c.description = 'Just an example command'
  c.option '-f', '--foo string', 'Does some foo with <string>'
  c.option '-b', '--bar [string]', 'Does some bar with [string]'
  c.example 'Do some foo', 'jspec example --foo bar'
  c.example 'Do some bar', 'jspec example --bar'
  c.when_called do |args, options|
    p args
    p options.__hash__
    # options.__hash__[:foo]
    # options.__hash__[:bar]

And execute with:

$ jspec example

They may also be placed at ~/jspec/commands for global usage.

For more information on the command creation visit

Installing Support Projects

Lets say you need jQuery for your project, and wish to test against it. You could download jQuery manually, use an absolute uri to Google's CDN, or use the following command, which will install jQuery to spec/support/jquery.js. $ jspec install jquery

Alternatively we may specify the destination path: $ jspec install jquery spec/jquery.js

Or provide a specific version string: $ jspec install jquery --release 1.3.1

The install command will also install Rhino for you (MacOS only) so you can run specs, and js via the command-line. $ jspec install rhino

To view the current projects supported view: $ jspec help install


JSpec provides transparent support for Rhino, while using the Terminal reporter. Simply create a JavaScript file with contents similar to below, and then execute the command following it:


.run({ reporter: JSpec.reporters.Terminal, failuresOnly: true })

Initialize project with: $ jspec init myproject

Run with: $ jspec run --rhino

Or bind (automated testing): $ jspec --rhino


The Ruby JavaScript testing server included with JSpec simply runs the spec suites within each browser you specify, while reporting result back to the terminal. It is essentially the same as using the DOM reporter and auto-testing each browser, however results are centralized to the terminal, removing the need to manually view each browser's output.

When utilizing the server if a file named spec/jspec.rb (or jspec/jspec.rb for rails) is present, then it will be loaded before the server is started. This allows you to add Sinatra routes, support additional Browsers, etc.

Run with all supported browsers: $ jspec run --server

Run with specific browsers: $ jspec run --browsers Safari,Firefox,Chrome,Explorer

Run with alternative browser names: $ jspec run --browsers safari,ff,chrome,ie

Browsers supported in core:

  • Browser::Default (system default)
  • Browser::Safari
  • Browser::WebKit
  • Browser::Chrome
  • Browser::Firefox
  • Browser::Opera
  • Browser::IE

Supplied routes:

  • /slow/NUMBER
  • /status/NUMBER

For example $.get('/slow/4', function(){}) will take 4 seconds to reply, where as $.get('/status/404', function(){}) will respond with an 404 status code. Add additional Sinatra routes to the jspec.rb file to add your own functionality.

Interactive Shell

JSpec provides an interactive shell through Rhino, utilize with:

$ jspec shell

Or to specify additional files to load:

$ jspec shell lib/*.js

Or view additional shell help

$ jspec help shell

When running the shell JSpec provides several commands:

  • quit, exit
    • Terminate the shell session
  • p()
    • Inspect the object passed

Or add your own. In the examples below, foo will become a getter, so it can be invoked simply as $ foo where as bar is a regular function which must be called as $ bar("something"). = ['Does some foo', function(){ return 'something' }] = ['Does some bar', function(o){ return 'something' }]

Ruby on Rails

No additional gems are required for JSpec to work with rails, although jspec-rails has been created by 'bhauman'. JSpec supports Rails out of the box, simply execute:

$ jspec init --rails

Then while still in the root directory of your Rails project, run the following command which will bind to, and refresh your browsers automatically when any changes are made to ./public/javascripts/*.js or ./jspec/*.js

$ jspec

Or just like regular JSpec applications, run once:

$ jspec run

Or run via the terminal using Rhino:

$ jspec run --rhino

Supported Browsers

Browsers below are supported and can be found in server/browsers.rb, however your spec/server.rb file may support additional browsers.

  • Safari
  • WebKit
  • Chrome
  • Firefox
  • Opera
  • Internet Explorer

Known Issues

  • The preprocessor is not (yet) capable of multiline conversions. For example the following is invalid

    object.stub('getContentsOfURL').and_return(function(url){ return 'html' })

    In cases such as this, you may always revert to utilizing JSpec in a grammar-less form as follows:

    stub(object, 'getContentsOfURL').and_return(function(url){ return 'html' })

Additional JSpec Modules

More Information


Many ideas and bug reports were contributed by the following developers, thankyou for making JSpec more enjoyable, and bug free. If I have missed you on this list please let me know (aka the fellow who donated


(The MIT License)

Copyright (c) 2008 - 2010 TJ Holowaychuk

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.