We could do some additional asserts here.

```js
  User.staticMethod = function staticMethod() {};
  User.prototype.instanceMethod = function instanceMethod() {};
  
  var Customer = ds.define('Customer', {vip: Boolean}, {base: 'User'});

  assert(Customer.prototype instanceof User);
  asssert(Customer.staticMethod === staticMethod);
  asssert(Customer.prototype.instanceMethod === instanceMethod);
```