Hash merging

default.ini

[base]
data_working_dir = "/tmp"

local.ini

[base]
data_working_dir = "/root"

my_class.rb

class MyClass
  @instance = nil
  @config = nil
  @APP_ROOT = nil

  def initialize
    @APP_ROOT = File.expand_path __FILE__ + '/../../../'
  end

  def self.get_instance
    @instance = MyClass.new unless @instance

    @instance
  end

  def config custom_config_path = nil
    unless @config
      ini_file_config = {:escape => false}
      default_ini = IniFile.new( (@APP_ROOT + "/config/default.ini"), ini_file_config )

      if custom_config_path
        custom_ini   = IniFile.new( (custom_config_path), ini_file_config)
      else
        custom_ini   = IniFile.new( (@APP_ROOT + "/config/local.ini"), ini_file_config )
      end

      @config = default_ini.to_h.merge custom_ini.to_h
    end

    @config
  end

  def self.clean_ini_value ini_value
    ini_value.match(/[\/\w]+/).to_a.last
  end
end

my_class_spec.rb

require File.expand_path(__FILE__ + "/../../spec_helper.rb")

describe "MyClass" do
  it "overload configuration by custom_config" do
    testing_ini_path = File.expand_path(
        File.dirname(__FILE__) + '/../fixtures/local.ini'
    )

    app_data_wd = MyClass .get_instance \
                      .config(testing_ini_path) \
                       ['base']['data_working_dir']

    MyClass.clean_ini_value(app_data_wd).should eq '/root'
  end
end

result.log

# Terminal
expected: "/root"
got: "/tmp"

# RubyMine
1 example, 0 failures, 1 passed