Mongoose & unique field

I have the following schema with mongoose:

var SimSchema = new Schema({
    msisdn     : { type : String , unique : true, required : true },
    imsi       : { type : String , unique : true, required : true },
    status     : { type : Boolean, default: true},
    signal     : { type : Number },
    probe_name : { type:  String , required : true }
});

I have uniqueoption for the msisdn and imsi.

In some cases this condition is well respected. For the following mocha test:

"use strict";

var app      = require('../../app');
var http     = require('http');
var request  = require('supertest');
var mongoose = require('mongoose');
var should   = require('should');



describe('[ Sim controller ] ', function(){
  before(function(done) {
    app.set_env('test');
    this.server = app.start(function() {
      mongoose.connection.db.dropDatabase(function() {
        done();
      })
    });
  });


  beforeEach(function(done){
    done();
  });


  it('Sim with good parameters should be created in the database', function(done){
    var newSim = {
      msisdn:     '1234',
      imsi:       '007',
      probe_name: 'BOUCHON_1'
    };

    request(this.server)
      .post('/sims')
      .set('Content-Type', 'application/json')
      .send(newSim)
      .expect(200).end(function(err, res) {
        if (err) return done(err);
        res.body.should.have.property('imsi');
        res.body.should.have.property('probe_name');
        res.body.should.have.property('msisdn');
        setTimeout(function() {
          done();
        }, 1000);
      });
  });


  it('Sim imsi/msisdn is unique in the database', function(done){
    var newSim = {
      msisdn:     '1234',
      imsi:       '007',
      probe_name: 'BOUCHON_1'
    };

    request(this.server)
      .post('/sims')
      .set('Content-Type', 'application/json')
      .send(newSim)
      .expect(200).end(function(err, res) {
        if (err) return done(err);
        res.body.should.have.property('error').equal('Duplicate Item');
        done();
      });
  });


  after(function(done) {
    app.stop(done);
  });
});

It's working fine if I run it directly:

julio$ mocha test/controllers/ctrl_sim.js 

But If I run it thanks to the recessive option it failed:

  1) [ Sim controller ]  Sim imsi/msisdn is unique in the database:
     Uncaught AssertionError: expected { __v: 0,
  imsi: '007',
  msisdn: '1234',
  probe_name: 'BOUCHON_1',
  _id: '530a2b7f52273aa90783baf0',
  status: true } to have property 'error'

I read on stack that sometimes the unique condition is not well respected as the index is not refreshed. Do you think this is my case? In fact, I delete the database for each mocha test suite. Maybe mongo doesn't have the time to recreate all the indexes each time.

Any idea?

Use dropDups to ensure dropping duplicate records in your schemas like;

var SimSchema = new Schema({
    msisdn     : { type : String , unique : true, required : true, dropDups: true },
    imsi       : { type : String , unique : true, required : true, dropDups: true },
    status     : { type : Boolean, default: true},
    signal     : { type : Number },
    probe_name : { type:  String , required : true }
});

And before running your tests, restart mongodb