foo_provider.rb

class Foo

  attr_reader :adapter

  def initialize
    @adapter = if Rails.env.production?
      Foo::RealAdapter.new
    else
      Foo::StubAdapter.new
    end
  end
  
  # Class-level API
  # Instantiates and calls instance-level methods (below)
  class << self
    def add_bar
      new.add
    end
    
    def delete_bar
      new.delete
    end
  end
  
  # Instance-level API
  # Just delegates through to the adapter
  delegate :add, :delete, to: :adapter
  
end