Autotest.add_hook :initialize do |at|
  at.clear_mappings

  at.add_mapping(%r%^lib/(.*)\.rb$%) do |_, m|
    at.files_matching %r%^spec/#{m[1]}_spec\.rb$%
  end

  at.add_mapping(%r%^spec/.*\_spec\.rb$%) { |filename, _| filename }
end