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();
}