# encoding: utf-8

require 'spec_helper'

describe Algebra::Product, '#each' do
  subject { object.each { |tuple| yields << tuple } }

  let(:object) { described_class.new(left, right)                                     }
  let(:header) { Relation::Header.coerce([[:id, Integer], [:name, String]])           }
  let(:left)   { Relation.new(header.project([:id]), [[1], [2]])                      }
  let(:right)  { Relation.new(header.project([:name]), [['Dan Kubb'], ['Alex Kubb']]) }
  let(:yields) { []                                                                   }

  it_should_behave_like 'an #each method'

  it 'yields only tuples' do
    subject
    yields.each { |tuple| tuple.should be_instance_of(Tuple) }
  end

  it 'yields only tuples with the expected header' do
    subject
    yields.each { |tuple| tuple.header.should be(object.header) }
  end

  it 'yields only tuples with the expected data' do
    expect { subject }.to change { yields.dup }
      .from([])
      .to([[1, 'Dan Kubb'], [1, 'Alex Kubb'], [2, 'Dan Kubb'], [2, 'Alex Kubb']])
  end
end