# encoding: utf-8

require 'spec_helper'

describe Optimizer::Algebra::Rename::EmptyOperand, '#optimizable?' do
  subject { object.optimizable? }

  let(:header)   { Relation::Header.coerce([[:id, Integer]]) }
  let(:relation) { operand.rename(id: :other_id)             }
  let(:object)   { described_class.new(relation)             }

  before do
    expect(object.operation).to be_kind_of(Algebra::Rename)
  end

  context 'when the operand is an empty relation' do
    let(:operand) { Relation::Empty.new(header) }

    it { should be(true) }
  end

  context 'when the operand is not an empty relation' do
    let(:operand) { Relation.new(header, [[1]]) }

    it { should be(false) }
  end
end