Tobi ! Get' there !
No, I am not calling back my smart dog, but trying to integrate Tobi (a functional testing framework) into a beautiful web site.
THat's the fact, Tobi is a javascript API with a Human Language Oriented methods to test some web interface.
If you want to test some Login Form, you will be able to write something like this:
var tobi = require('tobi') , 
    app = require('./my/app') , 
    browser = tobi.createBrowser(app); 
browser.get('/login', function(res, $){ 
    $('form') 
      .fill({ username: 'tj', password: 'tobi' }) 
      .submit(function(res, $){ 
        res.should.have.status(200); 
        res.should.have.header('Content-Length'); 
        res.should.have.header('Content-Type', 'text/html; charset=utf-8'); 
        $('ul.messages').should.have.one('li', 'Successfully authenticated'); 
        browser.get('/login', function(res, $){ 
            res.should.have.status(200); 
            // We are finished testing, close the server app.close(); 
            $('ul.messages').should.have.one('li', 'Already authenticated'); 
        }); 
    }); 
});
With this smart javascript, you will be able to test login form with a 'tobi' password for a 'tj' user. and then detect if the authentication run ok or fail. And the descripted scenario is also testing the "Already authentified" process from this "/login" form.
Ready to test other things ?  go and visit this web site : https://github.com/LearnBoost/tobi
note:
This framework was discoverdI had just discovered this framework exploring the BrowserId.org feature from Mozilla !