Both .URL and .url should work (for compatibility reasons). On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS source.URL is "http://127.0.0.1:8000/eventsource/resources/event-stream.php" PASS source.url is "http://127.0.0.1:8000/eventsource/resources/event-stream.php" PASS source.URL === source.url is true PASS successfullyParsed is true TEST COMPLETE