# File lib/rubygems/gem_commands.rb, line 675
    def execute
      if options[:test]
        version = options[:version] || "> 0.0.0"
        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