I still don't think this test case fully shows, that a function is called _each time_ a default value is required. Im thinking something like this

```js
var defaultFunction = sinon.stub().returns(5)
var UserTable = this.sequelize.define('UserCol', {
  aNumber: {
    type: Sequelize.INTEGER,
    defaultValue: defaultFunction 
  }
}, { timestamps: true })

UserTable.sync({ force: true }).success(function() {
  UserTable.create().success(function(user) {
      UserTable.create().success(function(user2) {
        expect(user.aNumber).to.equal(5)
        expect(user2.aNumber).to.equal(5)
        expect(defaultFunction).to.have.been.called.twice
        done()
      })
    })
  })
})
```