Exemplos de testes com rspec

exemplo_01.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'

  gem 'rspec', '~> 3.10'
end

module Calc
  extend self

  def add(a, b); number(a) + number(b); end
  def sub(a, b); number(a) - number(b); end

  private

    def numeric_string?(value)
      value.is_a?(String) && value =~ /((\d+)?\.\d|\d+)/
    end

    def number(value)
      return value if value.is_a?(Numeric)
      return value.include?('.') ? value.to_f : value.to_i if numeric_string?(value)
      raise TypeError, 'the value must be Numeric or a String with numbers'
    end
end

require 'rspec/autorun'

RSpec.describe Calc do
  describe '.add' do
    context 'with numeric values' do
      it 'returns the sum of the values' do
        expect(Calc.add(1, 1)).to eq(2)

        expect(Calc.add(1.5, 1)).to eq(2.5)
      end
    end

    context 'with string values' do
      context 'and all of them are numbers' do
        it 'returns the sum of the values' do
          expect(Calc.add(1, '1')).to eq(2)

          expect(Calc.add('1.5', 1)).to eq(2.5)
        end
      end

      context "and some of them isn't a number" do
        it 'raises an error' do
          expect { Calc.add('a', 1) }.to raise_error(TypeError)
        end
      end
    end

    context 'with some invalid argument' do
      it 'raises an error' do
        expect { Calc.add([], '1') }.to raise_error(TypeError)

        expect { Calc.add('1.5', {}) }.to raise_error(TypeError)
      end
    end
  end
end

exemplo_02.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'

  gem 'rspec', '~> 3.10'
end

module Calc
  extend self

  def add(a, b); number(a) + number(b); end
  def sub(a, b); number(a) - number(b); end

  private

    def numeric_string?(value)
      value.is_a?(String) && value =~ /((\d+)?\.\d|\d+)/
    end

    def number(value)
      return value if value.is_a?(Numeric)
      return value.include?('.') ? value.to_f : value.to_i if numeric_string?(value)
      raise TypeError, 'the value must be Numeric or a String with numbers'
    end
end

require 'rspec/autorun'

RSpec.describe Calc do
  describe '.add' do
    context 'with numeric values' do
      it { expect(Calc.add(1, 1)).to eq(2) }
      it { expect(Calc.add(1.5, 1)).to eq(2.5) }
    end

    context 'with string values' do
      context 'and all of them are numbers' do
        it { expect(Calc.add(1, '1')).to eq(2) }
        it { expect(Calc.add('1.5', 1)).to eq(2.5) }
      end

      context "and some of them isn't a number" do
        it { expect { Calc.add('a', 1) }.to raise_error(TypeError) }
      end
    end

    context 'with some invalid argument' do
      it { expect { Calc.add([], '1') }.to raise_error(TypeError) }
      it { expect { Calc.add('1.5', {}) }.to raise_error(TypeError) }
    end
  end
end