Mocking database in node.js?

How would I mock out the database in my node.js application, which in this case uses mongodb as the backend for a blog REST API ?

Sure, I could set the database to a specific testing -database, but I would still save data and not test my code only, but also the database, so I am actually not doing unit testing but integration testing.
So what should one do? Create database wrappers as a middle layer between application and db and replace the DAL when in testing?

// app.js  
var express = require('express');
    app = express(),
    mongo = require('mongoskin'),
    db = mongo.db('localhost:27017/test?auto_reconnect');

app.get('/posts/:slug', function(req, res){
    db.collection('posts').findOne({slug: req.params.slug}, function (err, post) {
        res.send(JSON.stringify(post), 200);
    });
});

app.listen(3000);

// test.js
r = require('requestah')(3000);
describe("Does some testing", function() {

  it("Fetches a blogpost by slug", function(done) {
    r.get("/posts/aslug", function(res) {
      expect(res.statusCode).to.equal(200);
      expect(JSON.parse(res.body)["title"]).to.not.equal(null);
      return done();
    });

  });
));