Failing test case for Circle

gistfile1.js

"use strict";

// USAGE:
// npm install mongoose
// npm install async
// npm install mocha-mongoose
// node test.js

var mochaMongoose = require('mocha-mongoose');
var mongoose = require('mongoose');
var async = require('async');

// Create a connection to mongo
var mongoUrl = "mongodb://localhost/test";

mongoose.connect(mongoUrl);

// Display all queries
mongoose.set('debug', true);


var UserSchema = new mongoose.Schema({
  // User email, with unicity constraint
  email: { type: String, unique: true },
});
// Register model
mongoose.model('User', UserSchema);


var U = mongoose.model('User');

async.series([
  function clean(cb) {
    // Clean from previous tests
    mochaMongoose(mongoUrl, {noClear: true})(cb);
  },
  function first(cb) {
    // Create first user, everything should be fine
    var u = new U();
    u.email = "sad@circle.com";
    u.save(cb);
  },
  function second(cb) {
    // Create second user with same email; an err should be raised
    var u = new U();
    u.email = "sad@circle.com";
    u.save(cb);
  }
], function(err) {
  if(err && err.code === 11000) {
    console.log("UNICITY TEST SUCCESS");
  }
  else {
    // No errors raised
    console.log("SHOULD NEVER HAPPEN");
  }

  process.exit();
});