How should I model my code to maximize code re-use in this specific situation?

Question

Updated: See end of question for how I implemented the solution.

Sorry for the poorly-worded question, but I wasn\'t sure how best to ask it. I\'m not sure

Answer 1

I would say use Dependecy Injection. Basically, you pass an abstraction of the send method.

Something like:

interface IVendorMessageSender
{
    void SendMessage(Vendor v);
}

public class OutboxManager 
{
    IVendorMessageSender _sender;

    public  OutboxManager(IVendorMessageSender sender)
    {
        this._sender = sender; //Use it in other methods to call the concrete implementation
    }

    ...
}

Another approach, as already mentioned, inheritance.

In either case: try to remove DB retrieval code from this class. Use another abstraction for that (ie: passing an IDataProvider interface or something like that to the constructor). It will make your code more testable.