A helper for JSON interaction. Treat the hashes recursively

camel_snake_hash.rb

module Utilities
  # A helper for JSON interaction. Treat the hashes recursively
  module CamelSnakeHash
    # camelize and stringify keys
    def camelize_keys(value)
      case value
      when Array
        value.map { |v| camelize_keys(v) }
      when Hash
        Hash[value.map { |k, v| [k.to_s.camelize(:upper), camelize_keys(v)] }]
      else
        value
      end
    end

    # underscore and symbolize keys
    def underscore_keys(value)
      case value
      when Array
        value.map { |v| underscore_keys(v) }
      when Hash
        Hash[value.map { |k, v| [k.to_s.underscore.to_sym, underscore_keys(v)] }]
      else
        value
      end
    end
  end
end

module Utilities
  describe CamelSnakeHash do
    include CamelSnakeHash
    let(:snake_hash) do
      { array_of_hashes: [{ an_integer: 1, a_string: 'bonjour' }, { a_hash: { stuff: 'stuff' } }], stuff: 'stuff' }
    end

    let(:camel_hash) do
      { 'ArrayOfHashes' => [{ 'AnInteger' => 1, 'AString' => 'bonjour' }, { 'AHash' => { 'Stuff' => 'stuff' } }], 'Stuff' => 'stuff' }
    end

    it 'should camelize and stringify keys' do
      expect(camelize_keys(snake_hash)).to eq(camel_hash)
    end

    it 'should underscore and symbolize keys' do
      expect(underscore_keys(camel_hash)).to eq(snake_hash)
    end

    it 'should produce the same hash' do
      expect(camelize_keys(underscore_keys(camel_hash))).to eq(camel_hash)
      expect(underscore_keys(camelize_keys(snake_hash))).to eq(snake_hash)
    end
  end
end