public void Remove_ShouldDeleteAnObjectFromRelatedObjects()
        {
            //arrange
            var site = new Site {
                Blog = new Blog()
            };

            _context.Add(site);
            _context.Commit();

            //act
            _context.Remove(site.Blog);
            _context.Commit();


            //assert
            _context.AsQueryable <Blog>().Count().Should().Be(0);
            _context.AsQueryable <Site>().First().Blog.Should().BeNull();
        }