blueprints.rb

Post.blueprint do
  title "I like MongoDB!"
  body "I have a ton of reasons for that."
end

post.rb

class Post
  include MongoMapper::Document
  
  key :title, String
  key :body, String
end

post2.rb

class Post
  # ...
  validates_presence_of :title
end

post_spec.rb

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')

describe Post do
  before(:all) do
    @post = Post.make
  end
  
  it "should have a title" do
    @post.title.should == "I like MongoDB!"
  end
end

post_spec2.rb

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')

describe Post do
  it { should have_keys(:title, :body, String) }
  it { should validate_presence_of(:title) }
  # ...
end

spec_helper.rb

ENV["RAILS_ENV"] ||= 'test'
require File.expand_path(File.join(File.dirname(__FILE__),'..','config','environment'))
require 'spec/autorun'
require 'spec/rails'
require 'spec/blueprints'

Spec::Runner.configure do |config|
end

test.rb

config.gem "machinist_mongo", :lib => "machinist/mongo_mapper"

test2.rb

config.gem "remarkable_rails", :lib => "remarkable_rails"
config.gem "remarkable_mongo", :lib => "remarkable/mongo_mapper"