List the lineages of every node in a hash

hash_node_lineages.rb

#!/usr/bin/env ruby

class Hash
  def node_lineages
    reduce_to_node = Proc.new do |prefix_key,value|
      if value.is_a?(Hash)
        value.map do |child_key,child_value|
          new_prefix = [prefix_key,child_key].join('.')
          reduce_to_node.call(new_prefix,child_value)
        end
      elsif value.is_a?(Array)
        value.map do |child_item|
          new_prefix = "#{prefix_key}[]"
          reduce_to_node.call(new_prefix, child_item)
        end
      else
        [prefix_key, value].join('=')
      end
    end

    self.map do |key, value|
      reduce_to_node.call(key, value)
    end
  end
end

hash = { a: :b }
expected = 'a=b'
actual = hash.node_lineages
raise "Test failed : #{expected.inspect} expected, #{actual.inspect} actual" unless actual == expected

hash = { a: { b: :c, d: :e } }
expected = "a.b=c ; a.d=e"
actual = hash.node_lineages.join(';')
raise "Test failed : #{expected.inspect} expected, #{actual.inspect} actual" unless actual == expected

hash = {
  a: {
    b: :c,
    d: :e
    },
  f: [
    :g,
    :h,
    :i
    ]
  }
expected = <<-HEREDOC
a.b=c
a.d=e
f[]=g
f[]=h
f[]=i
HEREDOC
actual = hash.node_lineages.join("\n")
raise "Test failed : #{expected.inspect} expected, #{actual.inspect} actual" unless actual == expected

puts 'All tests OK :)'