    # File lib/rubygems/commands/check_command.rb, line 31
      def execute
        if options[:test]
          version = options[:version] || Gem::Requirement.default
          gem_spec = Gem::SourceIndex.from_installed_gems.search(get_one_gem_name, version).first
          Gem::Validator.new.unit_test(gem_spec)
        end

        if options[:alien]
          say "Performing the 'alien' operation"
          Gem::Validator.new.alien.each do |key, val|
            if(val.size > 0)
              say "#{key} has #{val.size} problems"
              val.each do |error_entry|
                say "\t#{error_entry.path}:"
                say "\t#{error_entry.problem}"
                say
              end
            else
              say "#{key} is error-free"
            end
            say
          end
        end

        if options[:verify]
          gem_name = options[:verify]
          unless gem_name
            alert_error "Must specify a .gem file with --verify NAME"
            return
          end
          unless File.exist?(gem_name)
            alert_error "Unknown file: #{gem_name}."
            return
          end
          say "Verifying gem: '#{gem_name}'"
          begin
            Gem::Validator.new.verify_gem_file(gem_name)
          rescue Exception => e
            alert_error "#{gem_name} is invalid."
          end
        end
      end