Should Domain Entities be exposed as Interfaces or as Plain Objects?

Question

Should Domain Entities be exposed as Interfaces or as Plain Objects ?

The User Interface :

public interface IUser
{
    string FirstName { get; set; }
           


        

Answer 1

Interfaces are normally considered to be "contracts" and would therefore define behavior. The other major use is for mocking, so that you could provide domain entities that were mock-ups instead of coming from a specific data source (and having dependencies on that source).

For a simple data transfer object, I can't see a lot of use for defining interfaces, but I'm willing to be proven wrong. I'd go with simple objects for this.