parsley/spec/models/unit_conversion_spec.rb

require 'rails_helper'

RSpec.describe UnitConversion do

  describe '.auto_unit' do
    it 'leaves units alone if reasonable' do
      expect(UnitConversion.auto_unit('1/2', 'tbsp')).to eq ['1/2', 'tbsp']
      expect(UnitConversion.auto_unit('2', 'cups')).to eq ['2', 'cups']
      expect(UnitConversion.auto_unit('1', 'c')).to eq ['1', 'c']
    end

    it 'leaves units alone if unknown' do
      expect(UnitConversion.auto_unit('1/16', 'splat')).to eq ['1/16', 'splat']
      expect(UnitConversion.auto_unit('4.5', 'dogs')).to eq ['4.5', 'dogs']
      expect(UnitConversion.auto_unit('0', '')).to eq ['0', '']
    end

    it 'converts standard volume units correctly' do
      expect(UnitConversion.auto_unit('6', 'tsp')).to eq ['2', 'tablespoon']
      expect(UnitConversion.auto_unit('24', 'tsp')).to eq ['1/2', 'cup']
      expect(UnitConversion.auto_unit('1/16', 'cup')).to eq ['1', 'tablespoon']
      expect(UnitConversion.auto_unit('1/48', 'cup')).to eq ['1', 'teaspoon']
      expect(UnitConversion.auto_unit('768', 'tsp')).to eq ['1', 'gallon']
    end

    it 'converts standard mass units correctly' do
      expect(UnitConversion.auto_unit('32', 'oz')).to eq ['2', 'pound']
      expect(UnitConversion.auto_unit('40', 'oz')).to eq ['2 1/2', 'pound']
      expect(UnitConversion.auto_unit('3/4', 'lb')).to eq ['12', 'ounce']
      expect(UnitConversion.auto_unit('0.0625', 'lb')).to eq ['1', 'ounce']
    end
  end

  describe '.get_value' do
    it 'returns rationals' do
      expect(UnitConversion.get_value('1/2')).to eq Rational(1, 2)
      expect(UnitConversion.get_value('1 1/2')).to eq Rational(3, 2)
      expect(UnitConversion.get_value('-1/2')).to eq Rational(-1, 2)
      expect(UnitConversion.get_value('-1 1/2')).to eq Rational(-3, 2)
      expect(UnitConversion.get_value('18 9/10')).to eq Rational(189, 10)
    end

    it 'returns decimals' do
      expect(UnitConversion.get_value('-1')).to eq -1.to_d
      expect(UnitConversion.get_value('1.0')).to eq 1.to_d
      expect(UnitConversion.get_value('5.56')).to eq "5.56".to_d
    end
  end

  describe '.convert' do
    it 'scales decimal numbers' do
      expect(UnitConversion.convert('1', '2', 'cup', 'cup')).to eq '2'
      expect(UnitConversion.convert('1.5', '2', 'cup', 'cup')).to eq '3'
      expect(UnitConversion.convert('4', '.5', 'cup', 'cup')).to eq '2'
      expect(UnitConversion.convert('4', '1/2', 'cup', 'cup')).to eq '2'
    end

    it 'scales rational numbers' do
      expect(UnitConversion.convert('1/2', '2', 'cup', 'cup')).to eq '1'
      expect(UnitConversion.convert('1 1/2', '2', 'cup', 'cup')).to eq '3'
      expect(UnitConversion.convert('4', '.5', 'cup', 'cup')).to eq '2'
      expect(UnitConversion.convert('4', '1/2', 'cup', 'cup')).to eq '2'
      expect(UnitConversion.convert('2', '1/3', 'cup', 'cup')).to eq '2/3'
    end

    it 'converts units' do
      expect(UnitConversion.convert('1/2', '1', 'cup', 'tbsp')).to eq '8'
      expect(UnitConversion.convert('8', '1', 'tablespoon', 'cup')).to eq '1/2'
      expect(UnitConversion.convert('1', '1', 'tablespoon', 'cup')).to eq '1/16'
      expect(UnitConversion.convert('2.0', '1', 'tablespoon', 'cup')).to eq '0.125'
      expect(UnitConversion.convert('2/3', '1', 'tablespoon', 'teaspoons')).to eq '2'
      expect(UnitConversion.convert('2', '4', 'teaspoons', 'tablespoons')).to eq '2 2/3'
    end

    it 'scales odd units without conversion' do
      expect(UnitConversion.convert('1/2', '2', 'slices', 'slices')).to eq '1'
      expect(UnitConversion.convert('4', '1/8', nil, nil)).to eq '1/2'
      expect(UnitConversion.convert('4', '1/8', 'slices', nil)).to eq '1/2'
      expect(UnitConversion.convert('4', '1/8', nil, 'slices')).to eq '1/2'
      expect(UnitConversion.convert('4', '1/8', 'slices', '')).to eq '1/2'
      expect(UnitConversion.convert('4', '1/8', '', 'slices')).to eq '1/2'
    end

    it 'converts and scales' do
      expect(UnitConversion.convert('1/2', '2', 'cup', 'tbsp')).to eq '16'
      expect(UnitConversion.convert('2.0', '1 1/2', 'tablespoon', 'cup')).to eq '0.188'
      expect(UnitConversion.convert('2', '1 1/2', 'tablespoon', 'cup')).to eq '3/16'
    end

    it 'converts from volume to mass' do
      expect(UnitConversion.convert('5', '1', 'cup', 'ounce', '5 oz/c')).to eq '25'
    end

    it 'converts from mass to volume' do
      expect(UnitConversion.convert('25', '1', 'ounce', 'cup', '5 oz/c')).to eq '5'
    end
  end

  describe '.parse' do
    it 'correctly parses strings to Units' do
      data = {
          '4 c' => Unitwise(4, 'cup'),
          '5.5 oz' => Unitwise(5.5, 'ounce'),
          '-4 tbsp' => Unitwise(-4, 'tablespoon'),
          '223 g/c' => Unitwise(223, 'gram/cup'),
          '1/3 c' => Unitwise("1/3".to_r, 'cup'),
          '-5/16 g' => Unitwise("-5/16".to_r, 'gram'),
          '2 1/2 c' => Unitwise("5/2".to_r, 'cup'),
          '1.03 gram/ml' => Unitwise(1.03, 'gram/milliliter')
      }

      data.each do |input, output|
        expect(UnitConversion.parse(input)).to eq output
      end
    end

    it 'raises UnknownUnitError with bad units' do
      data = [
          '5 cats',
          '33 gulps/thinking',
          '9.2 meeters/s2',
          '5/8 floor'
      ]

      data.each do |input|
        expect { UnitConversion.parse(input) }.to raise_error(UnitConversion::UnknownUnitError), "'#{input}' didn't raise"
      end
    end

    it 'raises UnparseableUnitError on malformed string' do
      data = [
          '55',
          '55.5',
          '-55',
          '-55.55',
          '5.5/2 cups',
          '2/3.0 cups',
          'ounce',
          '-.4 cups',
          'gallons 6',
          '5,5 tsp'
      ]

      data.each do |input|
        expect { UnitConversion.parse(input) }.to raise_error(UnitConversion::UnparseableUnitError), "'#{input}' didn't raise"
      end
    end
  end

  describe '.density?' do
    it 'returns true for any mass over volume unit' do
      data = [
          Unitwise(1, 'gram/cup'),
          Unitwise(1, 'pound/gallon'),
          Unitwise(1, 'ounce/tablespoon'),
          Unitwise(1, 'ounce/centimeter3')
      ]

      data.each do |input|
        expect(UnitConversion.density?(input)).to be_truthy
      end
    end

    it 'returns false for any non density unit' do
      data = [
          Unitwise(1, 'cup'),
          Unitwise(1, 'gram'),
          Unitwise(1, 'gram/hour'),
          Unitwise(1, 'centimeter3/ounce')
      ]

      data.each do |input|
        expect(UnitConversion.density?(input)).to be_falsey
      end
    end
  end

  describe '.rationalize' do
    it 'leaves integers alone' do
      expect(UnitConversion.rationalize(1)).to eq 1
      expect(UnitConversion.rationalize(15)).to eq 15
      expect(UnitConversion.rationalize(-1)).to eq -1
      expect(UnitConversion.rationalize(0)).to eq 0
    end

    it 'leaves non-fractional numbers alone' do
      expect(UnitConversion.rationalize(1.0)).to eq 1.0
      expect(UnitConversion.rationalize(-1.0)).to eq -1.0
      expect(UnitConversion.rationalize(0.0)).to eq 0.0
      expect(UnitConversion.rationalize(35.0)).to eq 35.0
    end

    it 'leaves already nice rationals alone' do
      expect(UnitConversion.rationalize(Rational(1,2))).to eq Rational(1,2)
      expect(UnitConversion.rationalize(Rational(5,2))).to eq Rational(5,2)
      expect(UnitConversion.rationalize(Rational(3,16))).to eq Rational(3,16)
      expect(UnitConversion.rationalize(Rational(3,4))).to eq Rational(3,4)
    end

    it 'converts neat decimals to rationals' do
      expect(UnitConversion.rationalize(1.5)).to eq Rational(3,2)
      expect(UnitConversion.rationalize(0.125)).to eq Rational(1,8)
      expect(UnitConversion.rationalize(5.0625)).to eq Rational(81, 16)
      expect(UnitConversion.rationalize(0.75)).to eq Rational(3,4)
    end

    it 'rounds weird rationals to nice rationals' do
      expect(UnitConversion.rationalize(Rational(3,7))).to eq Rational(7,16)
      expect(UnitConversion.rationalize(Rational(2,5))).to eq Rational(3,8)
      expect(UnitConversion.rationalize(Rational(2,5))).to eq Rational(3,8)
    end

    it 'rounds weird decimals to nice rationals' do
      expect(UnitConversion.rationalize(0.24)).to eq Rational(1,4)
      expect(UnitConversion.rationalize(1.24)).to eq Rational(5,4)
      expect(UnitConversion.rationalize(1.13)).to eq Rational(9,8)
    end
  end

  describe '.normalize_unit_name' do

    it 'converts simple units' do
      data = {
          'c' => '[cup_us]',
          'cups' => '[cup_us]',
          'pints' => '[pt_us]',
          'gram' => 'g',
          'grams' => 'g',
          'Grams' => 'g',
          'Tbsp' => '[tbs_us]'
      }

      data.each do |input, output|
        expect(UnitConversion.normalize_unit_names(input)).to eq output
      end
    end

    it 'converts mixed units' do
      data = {
          'oz/c' => '[oz_av]/[cup_us]',
          'kilograms/cups' => 'kg/[cup_us]',
          'pints/junk' => '[pt_us]/junk'
      }

      data.each do |input, output|
        expect(UnitConversion.normalize_unit_names(input)).to eq output
      end
    end

  end

end