Hello.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace MockingLib {

    public class Hello {

        private IRepo repo;

        public Hello(IRepo repo) {
            this.repo = repo;
        }

        public string Say() {
            return "The " + this.repo.Get() + " Thing";
        }

        public void Do(string thing) {
            this.repo.Put("The " + thing + " Thing");
        }
    }
}