require 'spec_helper'

describe Helper do
  include Helper
  context '#is_n?' do
    it { expect(0.zero?).to be true }
    it { expect(_(0).zero?).to be true }
    it { expect(inverse(0, :+).zero?).to be true }
    it { expect(1.one?).to be true }
    it { expect(_(1).one?).to be true }
    it { expect(inverse(1, :*).one?).to be true }
    it { expect(-1.minus1?).to be true }
    it { expect(_(-1).minus1?).to be true }
  end

  context '#multiple_of?' do
    it { expect(0.multiple_of?(x)).to be(true) }

    it { expect(4.multiple_of?(_(2))).to be(true) }
    it { expect(_(4).multiple_of?(2)).to be(true) }
    it { expect(_(4).multiple_of?(_(2))).to be(true) }

    it { expect(x.multiple_of?(x)).to be(true) }
    it { expect(x.multiple_of?(y)).to be(false) }

    it { expect((x * y).multiple_of?(x)).to be(true) }
    it { expect((x * y).multiple_of?(x)).to be(true) }
    it { expect((x * y).multiple_of?(z)).to be(false) }
  end

  context '#like_term?' do
    it { expect(x.like_term?(x)).to be true }
    it { expect((2 * x).like_term?((3 * x))).to be true }
  end

  context '#combinable?' do
    it { expect(:x.combinable?(:x, :+)).to be true }
    it { expect(:x.combinable?(2 * :x, :+)).to be true }
    it { expect((2 * :x).combinable?(:x, :+)).to be true }
    it { expect((2 * :x).combinable?(2 * :x, :+)).to be true }
    it { expect(:x.combinable?(:y, :+)).to be false }
    it { expect(1.combinable?(2, :+)).to be true }
    it { expect(:x.combinable?(:x, :*)).to be true }
    it { expect(:x.combinable?(:y, :*)).to be false }
    it { expect(1.combinable?(2, :*)).to be true }
    it { expect(0.combinable?(:x, :**)).to be true }
    it { expect(1.combinable?(:y, :**)).to be true }
  end

  context '#distributive?' do
    it { expect(distributive?(:+, :*)).to be true }
    it { expect(distributive?(:+, :/)).to be true }
    it { expect(distributive?(:-, :*)).to be true }
    it { expect(distributive?(:-, :/)).to be true }
    it { expect(distributive?(:*, :**)).to be true }
    it { expect(distributive?(:/, :**)).to be true }
    it { expect(distributive?(:*, :+)).to be false }
    it { expect(distributive?(:**, :*)).to be false }
  end

  it { expect(inverse(x, :+).inverse?(:+, x)).to be true }
  it { expect(x.inverse?(:+, inverse(x, :+))).to be true }
  it { expect(inverse(x, :*).inverse?(:*, x)).to be true }
  it { expect(x.inverse?(:*, inverse(x, :*))).to be true }
end