http://samueleresca.net/2015/05/asp-net-mvc-web-api-mockup-entity-framework-using-moq/

MVCMockUp_webAPI\Controller\LocationsController.cs

using Blog.MockingWebAPI.Repository;
using Bungles.FindDrinks.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace Bongles.WebAPI.Controllers
{
    ///
    /// LocationsController: returns information about your Location
    ///
    public class LocationsController : ApiController
    {

        public databaseEF db { get; set; }

        ///
        /// Default constructor
        ///
        public LocationsController()
        {
            this.db = new databaseEF();
        }

        ///
        /// Constructor used by Moq
        ///
        /// Repository 
        public LocationsController(databaseEF mockDB)
        {
            this.db = mockDB;
        }

        ///
        /// Controller used to get location by id
        /// GET api/values/id
        ///
        /// /// 
        public Location Get(int locationId)
        {
            //
            //Prendo quello con id corrispondente
            //
            return db.locations.Where(l => l.id == locationId).ToList().FirstOrDefault();
        }

    }
}