Estoy tratando de usar el proveedor de datos en mocha para escribir menos código

var should = require('should'); 
var assert = require('assert');
var request = require('supertest');  
var mongoose = require('mongoose');
var winston = require('winston');
var config = require('../app/config');

describe('Authentification', function() {
    var url = config.web.protocol + '://' + config.web.host + ':' + config.web.port;

    describe('signin',function()
    {
        var provider = [
            {
                describe: 'should return error trying to signin with empty body',
                body: {},
                status: 404,
                message: "firstName not found"
            },
            {
                describe: 'should return error trying to signin with no first name',
                body: {
                    lastName: 'test',
                    password: 'test',
                    email: 'test'
                },
                status: 404,
                message: "firstName not found"
            },
            {
                describe: 'should return error trying to signin with no last name',
                body: {
                    firtsName: 'test',
                    password: 'test',
                    email: 'test'
                },
                status: 404,
                message: "lastName not found"
            },
            {
                describe: 'should return error trying so signin with no password',
                body: {
                    lastName: 'test',
                    firstName: 'test',
                    email: 'test'
                },
                status: 404,
                message: "password not found"
            },
            {
                describe: 'should return error trying so signin with no email',
                body: {
                    lastName: 'test',
                    password: 'test',
                    firstName: 'test'
                },
                status: 404,
                message: "email not found"
            },
            {
                describe: 'should return error trying so signin a too long firstName',
                body: {
                    firstName: 'kldsfjghsldkglsqkdjghqlkfjdsghldfksjghfdlskjgkldjfsdj',
                    lastName: 'test',
                    password: 'testhdksjdhfb',
                    email: '[email protected]'
                },
                status: 400,
                message: "invalid firstName"
            },
        ];

        for (var i in provider) {
            it(provider[i].describe, function(done) {
            request(url)
                .post('/user/signin')
                .send(provider[i].body)
                .expect(provider[i].status)
                .expect(function(res)
                {
                    assert.equal(res.body.code, provider[i].status);
                    assert.equal(res.body.message, provider[i].message);
                })
                .end(done);
            });
        }
    });
});

Pero en este caso solo verifica la última prueba.

La salida es

  Authentification
    signin
      ✓ should return error trying to signin with empty body 
      ✓ should return error trying to signin with no first name 
      ✓ should return error trying to signin with no last name 
      ✓ should return error trying so signin with no password 
      ✓ should return error trying so signin with no email 
      ✓ should return error trying so signin a too long firstName 


  6 passing (71ms)

Pero si la última prueba falla, todas las demás fallan. y si una de las otras pruebas está mal, la prueba pasa.

Quizás haya un problema asincrónico, pero no sé cómo resolverlo.