_groups

# File lib/bundler/graph.rb, line 52
    def _groups
      relations = Hash.new {|h, k| h[k] = Set.new }
      @env.current_dependencies.each do |dependency|
        dependency.groups.each do |group|
          next if @without_groups.include?(group)

          relations[group.to_s].add(dependency)
          @relations[group.to_s].add(dependency.name)

          @node_options[group.to_s] ||= _make_label(group, :node)
          @edge_options["#{group}_#{dependency.name}"] = _make_label(dependency, :edge)
        end
      end
      @groups = relations.keys
      relations
    end