issue-107.rb

require 'mongoid'
require 'rspec'

Mongoid.configure do |config|
  config.master = Mongo::Connection.new.db('testing')
end

class Foo
  include Mongoid::Document

  field :size, :type => Integer

  collection.remove
end

Foo.create(:size => 4)
Foo.create(:size => 6)
Foo.create(:size => 8)
Foo.create(:size => 10)

Foo.where(:size.gt => 4).and(:size.lt => 10).size.should == 2