What does it mean when object extends class with no implementation

Question

object PostgresDriver extends PostgresDriver

I see this in slick with no implementation whatsoever. I am wonder does that just automatically create a singleton class?

Answer 1

This is pretty standard practice, defining a trait to represent the abstraction and then providing a standard implementation of that trait as an object. If you just do it as the object you don't have an abstraction to refer to it as and stuff like that can make mocking and testing difficult at the least