Entity framework unit test problem

EF_TDD.cs

        //works
        public void Update(Job job)
        {
            //How do you unit test this line without communicating with a DB?
            context_.Entry(job).State = EntityState.Modified;
            context_.SaveChanges();
        }

        //doesn't work
        public void Update(Job job)
        {
            //Can I make sure it doesn't get turned into this?
            context_.Entry(job).State = EntityState.Deleted;
            context_.SaveChanges();
        }