```ruby
# encoding: utf-8

# SimpleCov MUST be started before require 'ROM'
#
if ENV['COVERAGE'] == 'true'
  require 'simplecov'
  require 'coveralls'

  SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
    SimpleCov::Formatter::HTMLFormatter,
    Coveralls::SimpleCov::Formatter
  ]

  SimpleCov.start do
    command_name 'spec:unit'

    add_filter 'config'
    add_filter 'lib/rom/support'
    add_filter 'spec'

    add_group 'Finalizer',    'lib/rom/finalizer'
    add_group 'Mapper',       'lib/rom/mapper'
    add_group 'Relation',     'lib/rom/relation'
    add_group 'Relationship', 'lib/rom/relationship'
    add_group 'Attribute',    'lib/rom/attribute'

    #minimum_coverage 98.10  # 0.10 lower under JRuby
  end

end

class Mapper
  def load(tuple)
    tuple
  end

  def dump(object)
    object.to_h
  end
end

require 'shared_helper' # requires ROM
```

Add all RA ops to ROM::Relation
user
```ruby
# encoding: utf-8

# SimpleCov MUST be started before require 'ROM'
#
if ENV['COVERAGE'] == 'true'
  require 'simplecov'
  require 'coveralls'

  SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
    SimpleCov::Formatter::HTMLFormatter,
    Coveralls::SimpleCov::Formatter
  ]

  SimpleCov.start do
    command_name 'spec:unit'

    add_filter 'config'
    add_filter 'lib/rom/support'
    add_filter 'spec'

    add_group 'Finalizer',    'lib/rom/finalizer'
    add_group 'Mapper',       'lib/rom/mapper'
    add_group 'Relation',     'lib/rom/relation'
    add_group 'Relationship', 'lib/rom/relationship'
    add_group 'Attribute',    'lib/rom/attribute'

    #minimum_coverage 98.10  # 0.10 lower under JRuby
  end

end

class Mapper
  def load(tuple)
    Hash[tuple.header.map { |attribute| [attribute.name, tuple[attribute]] }]
  end

  def dump(object)
    object
  end
end

require 'shared_helper' # requires ROM
```
assistant