Implement "map" function from ruby's arrays to understand how blocks work

pmap.rb

require 'minitest/autorun'

# Good blog article https://eli.thegreenplace.net/2006/04/18/understanding-ruby-blocks-procs-and-methods

# Extends 'Array' adding the pmap method which is equivalent to map
class Array
  # def pmap(&block)
  #   map(&block)
  # end
  def pmap(&block)
    results = []
    to_ary.each do |x|
      results.push(yield(x))
      # Also works:
      # results.push(block.call(x))
    end
    results
  end
end


class PmapTest < Minitest::Test
  def test_empty
    result = [].pmap { |x| x }
    assert_equal [], result
  end

  def test_simple
    result = [1, 2, 3].pmap { |x| x + 1 }
    assert_equal [2, 3, 4], result
  end

  def test_simple_amp_syntax
    result = [1, 0, 2].pmap(&:zero?)
    assert_equal [false, true, false], result
  end
end