User model

index.js

var db = require('db');
// do some init here, or connect
db.init();

var userModel = require('User')({
  db: db
});

userModel.create(function (err, user) {
  
});

test.js

var test = require('tape');
var userModel = require('User');

test('it creates a user with id', function (t) {
  var user = {
    id: 1
  };
  var fakeDb = {
    query: function (done) {
      done(null, user);
    }
  }
  
  userModel({
    db: fakeDb
  }).create(function (err, user) {
    t.equal(user.id, 1, 'User id should match');
    t.end();
  })
  
});

User.js

function userModel (options) {
  var db;
  
  if (!options.db) {
    throw new Error('Options.db is required');
  }
  
  db = options.db;
  
  return {
    create: function (done) {
      db.query('INSERT ...', done);
    }
  }
}

module.exports = userModel;