Entity Framework DbSet NSubsitute Helper

DbSetNSubsituteHelper.cs

using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using NSubstitute;

namespace ConsoleApplication
{
    public static class EntityFrameworkHelper
    {
        public static DbSet<R> AsDbSetSubstitute<R>(this IEnumerable<R> data) where R : class
        {
            var dataQuarebale = data.AsQueryable();
            var dbSet = Substitute.For<DbSet<R>, IQueryable<R>>();

            dbSet.InitializeDbSet<R>(dataQuarebale);

            return dbSet;
        }

        public static void InitializeDbSet<R>(this DbSet<R> dbSet, IQueryable<R> data) where R : class
        {
            var dbSetQuarebale = (IQueryable<R>)dbSet;
            dbSetQuarebale.Provider.Returns(data.Provider);
            dbSetQuarebale.Expression.Returns(data.Expression);
            dbSetQuarebale.ElementType.Returns(data.ElementType);
            dbSetQuarebale.GetEnumerator().Returns(data.GetEnumerator());
        }
    }
}