Discover what methods in a class are actually being used. Either use dependency injection or completely replace your object with this one.

whaty_is_my_public_api.rb

class WhatIsMyPublicApi < BasicObject
  def initialize(*arguments)
    method_missing('initialize', *arguments)
  end

  def method_missing(method, *arguments)
    ::File.open('what_is_my_public_api.log', 'a') do |f|
      args = arguments.inspect.gsub(/^\[|\]$/, '')
      f.write("#{method}(#{args})\n")
    end
  end
end