test harness for posted code wanting refactoring

original_with_test_harness.rb

class LocaleChooser


  LOOKUP_CHAIN = [:params, :user, :session, :http, :default]

  def self.set_by(inputs)
    locale = nil
    LOOKUP_CHAIN.each do |lookup|
      locale = send("by_#{lookup}", inputs[lookup])
      break if locale
    end
    return locale
  end


  # define self.by_params(input), self.by_user(input), etc.
  class << self
    returning_lookups = [:user, :http] # edit me for testing

    LOOKUP_CHAIN.each do |lookup|
      define_method("by_#{lookup}") do |input|
        puts "evaluated by_#{lookup}"

        if returning_lookups.include?(lookup)
          return [lookup, input]
        else
          return nil
        end
      end
    end
  end
end

p LocaleChooser.set_by({})
puts '---'
p LocaleChooser.set_by(:user => :custom_user) 
puts '---'
p LocaleChooser.set_by(:default => :custom_default)
puts '---'
p LocaleChooser.set_by(:params => :custom_params)

output_as_is.txt

evaluated by_params
evaluated by_user
[:user, nil]
---
evaluated by_params
evaluated by_user
[:user, :custom_user]
---
evaluated by_params
evaluated by_user
[:user, nil]
---
evaluated by_params
evaluated by_user
[:user, nil]

This comment of mine on the Gist I forked this from explains the origin of this code and how to use it.