parsley/spec/models/unit_conversion_spec.rb

require 'rails_helper'

RSpec.describe UnitConversion do

  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)
    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'
    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'
    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')
      }

      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 '.normalize_unit_name' do

    it 'converts simple units' do
      data = {
          'c' => 'cup',
          'cups' => 'cup',
          'pints' => 'pint',
          'g' => 'gram',
          'grams' => 'gram'
      }

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

    it 'converts mixed units' do
      data = {
          'oz/c' => 'ounce/cup',
          'kg/cups' => 'kilogram/cup',
          'pints/junk' => 'pint/junk'
      }

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

  end

end