Recursive stubs with method expectations for things like arel query chains

gistfile1.rb

class ChainStub
  attr_accessor :instance, :result
  def initialize(instance)
    @instance = instance
    @result = Object.new
  end 

  def method_missing(method_name, *args, &blk)
    if blk 
      instance.stub(method_name).with(*args) { blk.call }
      nil 
    else
      instance.stub(method_name).with(*args) { result }
      self.class.new(result)
    end 
  end 
end

def ChainStub(instance)
  ChainStub.new(instance)
end

instance = Object.new
result = [Object.new]
ChainStub(instance).where(:herp => 'derp').scoped_to_store(1) { result }
instance.where(:herp => 'derp').scoped_to_store(1).should == result