Property-based testing library (à lá QuickCheck/ScalaCheck).


Claire is a random testing library for both property-based testing (QuickCheck-like) and random program generation (ScalaCheck command's like), which allows you to express your code's behaviours and invariants in a clear way.

var claire = require('claire')
var _      =
var forAll = claire.forAll
var commutative_p = forAll( _.Int, _.Int ).satisfy( function(ab) {
                      return a + b == b + a
// + OK passed 100 tests. 
var identity_p = forAll(_.Int).satisfy(function(a) {
                   return a == a + 1
identity_p.asTest({ verbose: true, times: 100 })()
// <property failed>: ! Falsified after 1 tests, 1 failed. 
// : Failure #1 -------------------- 
// : The following arguments were provided: 
//   0 - 93 (<int>) 
// (Stack trace) 

The easiest way is to grab it from NPM (use Browserify if you're on a browser):

$ npm install claire

If you really want to continue suffering with old and terrible module systems (or use no module system at all), you can run make bundle yourself:

$ git clone git://
$ cd claire
$ npm install
$ make bundle
# Then use `dist/claire.umd.js` wherever you want.

A reference of the API can be built using Calliope:

$ npm install -g calliope
$ calliope build

A fully narrated documentation explaining the concepts behind the library is planned for a future release. Current WIP can be found at

Claire should work neatly in all ES5 platforms. ES3 platforms (IE8-, etc) can use es5-shim to provide the fallbacks necessary.

Things are frozen to ensure immutability, but legacy engines can do without, so Object.freeze = function(a) { return a } is okay.

For node:

$ npm test

For the browser:

$ npm install -g brofist-browser
$ make test
$ brofist-browser serve test/specs
# Then point your browsers to the URL on yer console

MIT/X11. ie.: do whatever you want.