data_mapper_spec_example.rb

# file 'fruit_mapper.rb'
class FruitMapper < DataMapper::Mapper
  map :id, Integer
  map :name, String
  map :taste, String
end

# file 'fruit_mapper_spec.rb'
require 'fruit_mapper'
describe FruitMapper do
end

# Gemfile
# ...
gem 'dm-mapper', :path => File.expand_path("../../dm-mapper", __FILE__)

# execution
bundle exec fruit_mapper_spec.rb