string_titleize_patch.rb

require "active_support/inflector"

# http://api.rubyonrails.org/classes/ActiveSupport/Inflector.html#method-i-titleize

module LocaleDependentTitleize
  def titleize(word)
    return humanize(underscore(word)) if I18n.locale == :pl
    super
  end
end

ActiveSupport::Inflector.prepend(LocaleDependentTitleize)
ActiveSupport::Inflector.singleton_class.prepend(LocaleDependentTitleize)

if __FILE__ == $PROGRAM_NAME
  require "minitest/autorun"

  describe "titleize" do
    let(:string) { "test_string_id" }

    describe "pl locale" do
      before do
        I18n.available_locales = [:pl, :en]
        I18n.locale = :pl
      end

      it "capitalize only first word" do
        string.titleize.must_equal "Test string"
        ActiveSupport::Inflector.titleize(string).must_equal "Test string"
        Class.new { include ActiveSupport::Inflector }.new.titleize(string).must_equal "Test string"
      end
    end

    describe "en locale" do
      before do
        I18n.locale = :en
      end

      it "capitalize all words" do
        string.titleize.must_equal "Test String"
        ActiveSupport::Inflector.titleize(string).must_equal "Test String"
        Class.new { include ActiveSupport::Inflector }.new.titleize(string).must_equal "Test String"
      end
    end
  end
end