Ruby implementation for Elixir cond

elixir.ex

defmodule Validator do
  def validate_age(age) do
    cond do
      age < 18 -> "Under 18"
      age < 21 -> "Under 21"
      true -> "Adult"
    end
  end
end

elixir.rb

class Elixir
  def cond(*assertions)
    return assertions.compact.first
  end

  def if(assertion, block)
    return block.call() if assertion == true
  end
end

elixir_spec.rb

RSpec.describe Elixir do
  let(:elixir) { described_class.new }

  describe "cond" do
    
    specify do
      result = elixir.cond(
        elixir.if(false, -> { return 1 }),
        elixir.if(true, -> { return 2 }),
        elixir.if(true, -> { return 3 })
      )

      expect(result).to eq(2)
    end

  end

  describe "if" do
    specify do
      result = elixir.if(true, -> { 1 })

      expect(result).to eq(1)
    end

    specify do
      result = elixir.if(false, -> { 1 })

      expect(result).to eq(nil)
    end
  end
end