Craig Muth wrote:
> Chris Carter and I threw together a simple gem to help create nested
> hierarchies (without relying on constructors).  Sample usage:
> 
>  require 'lay'
>  car = Car.lay( :color => "Red", :driver => Driver.lay( :name => "Bob" ) )

There looks to be overlap with Mocha 
(http://mocha.rubyforge.org/classes/Mocha/AutoVerify.html#M000005), 
though, judging from your "Other features" section, not 100%.