math_spec.rb

require 'spec_helper'

describe Ramda::Math do
  let(:r) { Ramda }

  context '#add' do
    it 'from docs' do
      expect(r.add(2, 3)).to be(5)
    end

    it 'is curried' do
      expect(r.add(2).call(3)).to be(5)
    end
  end

  context '#dec' do
    it 'from docs' do
      expect(r.dec(42)).to eq(41)
    end
  end

  context '#divide' do
    it 'from docs' do
      expect(r.divide(71, 100)).to eq(0.71)
    end

    it 'supports placeholder' do
      half = r.divide(Ramda.__, 2)
      expect(half.call(10)).to eq(5)
    end

    it 'is curried' do
      expect(r.divide(1).call(4)).to eq(0.25)
    end
  end

  context '#inc' do
    it 'from docs' do
      expect(r.inc(42)).to eq(43)
    end
  end

  xcontext '#math_mod' do
    it 'from docs' do
      expect(R.math_mod(-17, 5)).to eq(3)
      expect(R.math_mod(17, 5)).to eq(2)
      expect(R.math_mod(17, -5)).to be(nil)
      expect(R.math_mod(17, 0)).to be(nil)
      expect(R.math_mod(17.2, 5)).to be(nil)
      expect(R.math_mod(17, 5.3)).to be(nil)

      seventeen_mod = R.mathMod(17)
      expect(seventeen_mod.call(3)).to eq(2)
      expect(seventeen_mod.call(4)).to eq(1)
      expect(seventeen_mod.call(10)).to eq(7)
    end
  end

  context '#mean' do
    it 'returns mean of a nonempty list' do
      expect(R.mean([2])).to eq(2)
      expect(R.mean([2, 7])).to eq(4.5)
      expect(R.mean([2, 7, 9])).to eq(6)
      expect(R.mean([2, 7, 9, 10])).to eq(7)
    end

    it 'returns Nil for an empty list' do
      expect(R.mean([])).to be_nan
    end
  end

  context '#median' do
    it 'returns middle value of an odd-length list' do
      expect(R.median([2])).to eq(2)
      expect(R.median([2, 9, 7])).to eq(7)
    end

    it 'returns mean of two middle values of a nonempty even-length list' do
      expect(R.median([7, 2])).to eq(4.5)
      expect(R.median([7, 2, 10, 9])).to eq(8)
    end

    it 'returns NaN for an empty list' do
      expect(R.median([])).to be_nan
    end
  end

  context '#modulo' do
    it 'from docs' do
      expect(r.modulo(0, 3)).to be(0)
      expect(r.modulo(42, 2)).to be(0)
      expect(r.modulo(21, 2)).to be(1)
      expect(r.modulo(17, 3)).to be(2)
    end

    it 'supports placeholer' do
      is_odd = R.modulo(R.__, 2)
      expect(is_odd.call(42)).to eq(0)
      expect(is_odd.call(21)).to eq(1)
    end
  end

  context '#multipy' do
    it 'from docs' do
      triple = r.multiply(3)

      expect(triple.call(4)).to be(12)
      expect(r.multiply(2, 5)).to be(10)
    end

    it '#curried' do
      expect(r.multiply(2).call(5)).to eq(10)
    end
  end

  context '#negate' do
    it 'from docs' do
      expect(R.negate(42)).to eq(-42)
    end
  end

  context '#product' do
    it 'from docs' do
      expect(r.product([2, 4, 6, 8, 100, 1])).to be(38_400)
    end
  end

  context '#subsctrcat' do
    it 'from docs' do
      expect(r.subtract(10, 8)).to be(2)

      minus5 = r.subtract(17)
      expect(minus5.call(5)).to be(12)

      complementary_angel = r.subtract(90)
      expect(complementary_angel.call(30)).to be(60)
      expect(complementary_angel.call(72)).to be(18)
    end

    it 'support placeholder' do
      minus5 = r.subtract(R.__, 5)
      expect(minus5.call(17)).to eq(12)
      expect(minus5.call(10)).to eq(5)
    end
  end

  context '#sum' do
    it 'from docs' do
      expect(r.sum([2, 4, 6, 8, 100, 1])).to be(121)
    end
  end
end