]          @node_group_d.should be_valid         @node_group_d.errors.should be_empty         @node_group_d.node_groups.should include(@node_group_a,@node_group_b)       end     end      describe "by name" do       it "should not allow a group to include itself" do         @node_group_a.assigned_node_group_names = @node_group_