# encoding: utf-8

require 'spec_helper'

describe Optimizer::Algebra::Restriction::CombinationOperand, '#optimizable?' do
  subject { object.optimizable? }

  let(:left)      { Relation.new([[:id, Integer], [:user_name, String]], LazyEnumerable.new([[1, 'Dan Kubb']]))     }
  let(:right)     { Relation.new([[:id, Integer], [:employee_name, String]], LazyEnumerable.new([[2, 'Dan Kubb']])) }
  let(:operand)   { left.join(right)                                                                                }
  let(:relation)  { operand.restrict { predicate }                                                                  }
  let(:object)    { described_class.new(relation)                                                                   }

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

  context 'when the predicate distributes to the left' do
    let(:predicate) { left[:user_name].eq('Dan Kubb') }

    it { should be(true) }
  end

  context 'when the predicate distributes to the right' do
    let(:predicate) { right[:employee_name].eq('Dan Kubb') }

    it { should be(true) }
  end

  context 'when the predicate distributes to the left and right' do
    let(:predicate) { left[:id].eq(1) }

    it { should be(true) }
  end

  context 'when the predicate does not distribute to the left or right' do
    let(:predicate) { left[:user_name].eq(right[:employee_name]) }

    it { should be(false) }
  end
end