Both .URL and .url attributes should work (for compatibility reasons).

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".

PASS ws.url is "ws://127.0.0.1:8880/"
PASS ws.URL is "ws://127.0.0.1:8880/"
PASS ws.URL === ws.url is true
PASS successfullyParsed is true

TEST COMPLETE