superclient

using it is pretty easy:

configure routing

    var superclient = require('superclient');
    
    // create a constructor by configuring the routing
    var Client = superclient(function() {
        // adds a basic route '/test'
        this.route('test');
        
        // adds a resource route '/images' and '/images/:id'
        this.resource('images');
        
        // add another resource route '/users' and '/users/:id'
        this.resource('users', function() {
            // this adds a sub-route `/users/:id/profile`
            this.route('profile');
        });
    });

Client is a constructor that takes an optional prefix and a function which is called for every request. This is how you can delegate to supertest or superagent.

    // prefix all URLs with 'api'
    var api = new Client('api', function performRequest(verb, url) {
        return superagent[verb](url); // superagent(express)[verb](url)
    });

Now this api object is a fluent interface to the routing that was configured previously:

    // remember we specified the prefix 'api'
    api.foo // undefined
    api.test // a 'handler' which has HTTP verbs on it
    api.test.get() // superagent.get(/api/test)
    
    // the call goes through to super[agent|test] like normal
    api.users.post().send({ name: 'new user' }); // superagent.post(/api/users)
    
    api.users(123).put() // superagent.put(/users/123)
    api.users(123).profile.get() // superagent.get(/users/123/profile)

The configuration step can be done separately and even exported as it's own package - since the request handling is provided late, you can use it as a real API client as well as for testing said API itself. Also since the prefix is determined outside of the routing structure this can come in handy (service location, etc.)

things to add:

it would be interesting to support arbitrarily nested routing, including subresources i.e. /foo/:foo_id/someRoute/bar/:bar_id

it might also be ineresting to take a URL as a 'step' to build from, so if you get a Created response with a Location header, something like:

    api.users.post({ /* ... */ }).then(function() {
        var location = '/users/9000'; // assume that's the header
        var user = api.users(/* undefined id */).url(location) // 'set' the url up to this point
        user.profile.get() // GET /users/9000/profile
    })