require 'spec_helper'

describe Gitlab::SQL::CTE, :postgresql do
  describe '#to_arel' do
    it 'generates an Arel relation for the CTE body' do
      relation = User.where(id: 1)
      cte = described_class.new(:cte_name, relation)
      sql = cte.to_arel.to_sql
      name = ActiveRecord::Base.connection.quote_table_name(:cte_name)

      sql1 = ActiveRecord::Base.connection.unprepared_statement do
        relation.except(:order).to_sql
      end

      expect(sql).to eq("#{name} AS (#{sql1})")
    end
  end

  describe '#alias_to' do
    it 'returns an alias for the CTE' do
      cte = described_class.new(:cte_name, nil)
      table = Arel::Table.new(:kittens)

      source_name = ActiveRecord::Base.connection.quote_table_name(:cte_name)
      alias_name = ActiveRecord::Base.connection.quote_table_name(:kittens)

      expect(cte.alias_to(table).to_sql).to eq("#{source_name} AS #{alias_name}")
    end
  end

  describe '#apply_to' do
    it 'applies a CTE to an ActiveRecord::Relation' do
      user = create(:user)
      cte = described_class.new(:cte_name, User.where(id: user.id))

      relation = cte.apply_to(User.all)

      expect(relation.to_sql).to match(/WITH .+cte_name/)
      expect(relation.to_a).to eq(User.where(id: user.id).to_a)
    end
  end
end