class Node < ApplicationRecord
    belongs_to :parent, :class_name => "Node"
    has_many :children, :class_name => "Node", :foreign_key => "parent_id"

    validates :name, presence: true
end

it 'created successfully' do
        node = Node(name:"test1", parent_id:1).save
        expect(node).to be_truthy
    end

    it 'has root category' do
        expect(Node.where('parent_id = id').count).to eq(1)
    end