config.rb

require 'singleton'
#require 'awesome_print'
module DeployMaster
end

class DeployMaster::Config
    include Singleton

    CONFIG_LOCATION = 'deploy.yml'

    def self.config_location
        CONFIG_LOCATION
    end

    attr_reader :config

    def initialize
        @config = load_config_yaml
    
        # Run lots of functions to edit the config
    end

    
    def load_config_yaml
        raise "You do not have a deploy.yml configuration file at #{config_location}" if !File.exists?(DeployMaster::Config.config_location)
        YAML.load(File.open(DeployMaster::Config.config_location))
    end
end

nginx.rb

class DeployMaster::Nginx
    def initialize(server_name)
        setup_this_servers_config_only(server_name)
    end

    def load_config
        DeployMaster::Config.instance.config
    end

    def setup_this_servers_config_only(server_name)
        @server_name = server_name
        @config      = load_config

        # remove all the apps that do not have any stages set up on this server
        @config['apps'].reject! {|app_name, app_config|  !app_config.search('stages/*/server').values.include?(server_name) }
        # Remove all stages that are not setup on that server
        @config.search('apps/*/stages/*').reject! {|element|  element[:value]['server'] != server_name}
    end
end

nginx_spec.rb

base = File.expand_path(File.dirname(__FILE__) + '/../..')
require "#{base}/spec/spec_helper"
require "#{base}/lib/deploy_master/01_config"
require "#{base}/lib/deploy_master/11_nginx"

describe 'nginx' do
    describe 'generate_url_redirections_text_for' do
        it 'should return the url redirections for all apps and stages' do
            # Change the yaml file which is loaded
            DeployMaster::Config.stub(:config_location).and_return(File.dirname(__FILE__) + '/../test_config_yamls/06_test_deploy_for_url_config.yaml')
           
            apps_config = DeployMaster::Nginx.new('production').config['apps']

            result = nginx.generate_url_redirections_text_for(apps_config)

            expected_result = 0

            result.should == expected_result
        end
    end
end