text: // META: title=EventSource: stringify argument
        async_test(function (test) {
          test.step(function() {
            var source = new EventSource({toString:function(){return "resources/message.py";}})
            source.onopen = function(e) {
              test.step(function() {
                assert_false(e.hasOwnProperty('data'))
                source.close()
                test.done()
              })
            }
          });
        }, document.title + ', object');
  
        test(function(){
          var source = new EventSource(1);
          assert_regexp_match(source.url, /\/1$/);
        }, document.title + ', 1');
        test(function(){
          var source = new EventSource(null);
          assert_regexp_match(source.url, /\/null$/);
        }, document.title + ', null');
        test(function(){
          var source = new EventSource(undefined);
          assert_regexp_match(source.url, /\/undefined$/);
        }, document.title + ', undefined');
  
  