What is the Humble Object pattern and when is it useful?

Question

I was reading an article by Dino Esposito on how to test AsyncConrollers in ASP.NET MVC and in there he uses the \"Humble Object\" pattern, without going into much detail.

Answer 1

I'd usually implement this kind of this as an Interface - then you can use a mocking framework to stub it for testing, and an IoC framework to inject the correct implementation at runtime.

Here's an example from my current project:

public interface IUserInterface
{
    string AskUserWhereToSaveFile(
        string title, 
        FileType defaultFileType, 
        string defaultFileName = null, 
        params FileType[] otherOptions
    );

    string AskUserToSelectFileToLoad(
       string title, 
       FileType defaultFileType, 
       params FileType[] fileTypes
    );

    void ShowError(string title, string details);
    bool AskUserIfTheyWantToRetryAfter(string errorMessage);
}

My Controller then has a dependancy on IUserInterface rather than a concrete view, which allow me to replace user interactions with a stub for testing.