Sinon.js + Backbone : jQuery deferred are never trigerred

spec.js

TestModel = Backbone.Model.extend({
  url: '/test'
});

describe ('Model', function () {
  it('should be able to change password (fake server)', function() {
    var model, promise, request, server;
    
    server = sinon.fakeServer.create();
    
    model = new TestModel();
    promise = model.save({test: true});
    
    server.respondWith("PUT", "/test",
    [
      200, 
      {"Content-Type": "application/json"}, 
      JSON.stringify({success:true})
    ]);
    
    promise.done(function(data) {
      // Point never reached!
      console.log('Done!');
    });
    server.respond();
    
    request = server.requests[0];
    expect(request.method).toEqual('PUT');
    expect(request.url).toEqual('/test');
    expect(JSON.parse(request.requestBody)).toEqual({test:true});
    
    server.restore();
  });
});