entity framework 4 IObjectSet include

I am using EF4 CPT4 Code first and I have setup my ObjectContext to return IObjectSet so I would be able to Mock and test my repos. However, I now noticed that I am unable to use the .Include() method for eager loading like I would be able to if I used ObjectSet.

Is there a way to make th开发者_开发百科is work???

Edit: I added this extension method:

public static IQueryable<TSource> Include<TSource>(this IQueryable<TSource> source, string path)
{
    var objectQuery = source as ObjectQuery<TSource>;
    return objectQuery == null ? source : objectQuery.Include(path);
}

And it did add the Include() method, however I now get this error:

LINQ to Entities does not recognize the method 'System.Linq.IQueryable`1[PostHope.Core.DomainObjects.SiteAnnouncement] Include[SiteAnnouncement](System.Linq.IQueryable`1[PostHope.Core.DomainObjects.SiteAnnouncement], System.String)' method, and this method cannot be translated into a store expression. 

Response by EF Team:

This is a known issue with CTP4, Include is an instance method on ObjectSet but when your set is typed as IObjectSet you are actually using an extension method on IQueryable that is included in CTP4. This extension method doesn't work with compiled queries but we will try and support this in the next release.

~Rowan