Helper methods to load as few files as possible to get tests to run. Some create require paths to load files and others to init required constants.

example_usage.rb

require 'fast_spec_helper'
require 'date'
require_model 'generate_required_daily_lists'
required_constants %w(Distributor PackingList DeliveryList)

---- OR ----

require 'fast_spec_helper'
require_model 'exporter', sub_dir: 'sales_csv'
require_model 'delivery_exporter', sub_dir: 'sales_csv'
required_constants %w(DeliverySort DeliveryGenerator)

fast_spec_helper.rb

APP_ROOT       = '../..'
APP_MODEL_PATH = 'app/models'
LIB_MODEL_PATH = 'lib/models'

def defaults
  { app_path: APP_MODEL_PATH }
end

def require_model(name, opts = {})
  opts[:app_path] = LIB_MODEL_PATH if opts.delete(:lib)
  require_resource(name, opts)
end

def require_resource(name, opts = {})
  opts = defaults.merge(opts)
  require construct_path(name, opts)
end

def construct_path(name, opts = {})
  app_path_to_file = [ opts[:app_path] ]
  app_path_to_file << opts[:sub_dir] if opts[:sub_dir]
  app_path_to_file << name
  app_path_to_file = app_path_to_file.join('/') + '.rb'
  absolute_path(app_path_to_file)
end

def absolute_path(app_path_to_file)
  File.expand_path("#{APP_ROOT}/#{app_path_to_file}", __FILE__)
end

def required_constants(class_names)
  class_names.each do |class_name|
    unless Object.const_defined?(class_name)
      Object.const_set(class_name, Class.new)
    end
  end
end